Evaluation of pelvis

Ultrasound evaluation of the pelvis is often performed prior to ART to rule out any adnexal and uterine pathologies, such as polycystic ovary syndrome (PCOS), endometriosis, tubal disease, fibroids and endometrial polyps, which are clearly associated with aberrant and compromised outcomes during IVF.

The diagnosis of PCOS is currently based on the definition derived by the Rotterdam Consensus Workshop, which suggested the presence of 12 or more follicles measuring 2–9 mm in diameter and/or an ovarian volume of more than 10 cm³ for the ultrasound diagnosis (Balen et al 2003). Stromal vascularity and blood flow velocities are higher in women with polycystic ovaries (Agrawal et al 1998), and this may account for their tendency towards ovarian hyperstimulation in response to gonadotrophin therapy.

Endometriosis has been shown to have a negative effect on the outcome of ART, with affected women demonstrating a reduced response to ovarian stimulation (Gupta et al 2006); however, reports on its effects on embryo quality and implantation potential are conflicting. Moderate and severe degrees of endometriosis, often characterized by rectovaginal disease and the presence of ovarian endometrioma, can usually be diagnosed by transvaginal ultrasound (Moore et al 2002).

The presence of a hydrosalpinx is associated with poor implantation and pregnancy rates, and early pregnancy loss. The exact mechanism is unknown but substances toxic to the endometrium are thought to be produced that have a negative effect on endometrial receptivity (Strandell 2007). Salpingectomy, ideally performed laparoscopically, prior to IVF has been shown to be beneficial and is recommended. The diagnosis of hydrosalpinx can generally be made using transvaginal ultrasound with a high degree of confidence.

Ultrasound assessment of the uterus is generally restricted to measurement of the endometrial thickness and a description of the locality and size of any fibroids. Conventional ultrasound may also detect uterine anomalies, although these are more readily identified and correctly qualified with three-dimensional ultrasound. The diagnosis of uterine anomalies is important as they are associated with lower implantation rates and increased rates of early miscarriage, preterm labour and malpresentations (Lin 2004). The outcome appears to relate more to the length of the remaining uterine cavity than the degree of septum, and this may be measured reliably with three-dimensional ultrasound (Salim et al 2003).

The diagnosis and classification of fibroids into subserosal, intramural and submucosal is usually straightforward, and this is important as these have a progressively negative effect on pregnancy rates. Whilst intramural fibroids measuring more than 4 cm in diameter and submucous fibroids of any size are thought to have a negative effect on the outcome of fertility treatment and to be associated with lower pregnancy rates, the effect of smaller intramural fibroids on reproductive outcome is unclear (Oliveira et al 2004). There is also doubt about the exact impact of endometrial polyps, the other commonly encountered intrauterine pathology, on treatment outcome and early pregnancy. Some authors suggest conservative management, especially if the polyp is small (Isikoglu et al 2006), but this can be difficult in patients undergoing fertility treatment or with a history of miscarriage when a polyp is identified before treatment begins. Polyps are usually evident with conventional transvaginal imaging, although false-positive diagnoses are common. Saline infusion sonohysterography can reduce this and facilitate appropriate operative planning (Bartkowiak et al 2006). Delineation of the polyp with saline ensures that the size and position of the polyp can be defined accurately, allowing surgeons to modify their approach and resect the larger, more broad-based polyps rather than planning for simple polypectomy. Hysteroscopy is the gold standard technique for uterine cavity assessment, and may be necessary if diagnosis of intrauterine pathologies is in doubt.

Assessment of ovarian reserve

Evaluation of ovarian reserve has become an integral part of the pretreatment assessment of a woman about to undergo ART, and is recommended for all women planning ART (Speroff and Fritz 2005). The aim is to identify women likely to respond poorly, those who have a low chance of success and who are more likely to have their treatment cycle cancelled, and those prone to ovarian hyperstimulation which is associated with significant morbidity and even mortality. Accurate assessment of ovarian reserve and prediction of response therefore facilitates pretreatment counselling of couples of their potential risks, and allows treatment to be tailored to the individual, potentially increasing the number of oocytes retrieved without risking an exaggerated response. Ovarian reserve, defined by the size and quality of the remaining ovarian follicular pool at any given time, reflects the fertility potential of a woman (Broekmans et al 2006).

Although women’s age is an important predictor of ovarian reserve and response, a great deal of interindividual variation exists, even among women of the same age (te Velde and Pearson 2002). This is indicative of a wide variation in the rate of age-related decline in the ovarian follicle population. Several endocrine and ultrasound markers have been reported, with the aim of estimating the number of gonadotrophin-responsive or ‘selectable follicles’ more accurately. The endocrine markers include factors produced by the developing follicles [oestradiol, inhibin B and anti-Müllerian hormone (AMH)] or hormones under the inhibitory control of these factors [follicule-stimulating hormone (FSH)]. The ultrasound markers are antral follicle count, ovarian volume and ovarian vascularity. The sensitivities, specificities and predictive values of these tests have been evaluated in many studies by correlating the test results with the number of oocytes retrieved, poor or exaggerated ovarian response, and pregnancy or livebirth rates during ART (Broekmans et al 2006).

Evaluation of male partner

The male partner should be evaluated carefully. Clinical examination, semen analysis including sperm function tests, genetic assessment and biochemical tests show that the aetiology of male subfertility can be divided into four main groups as follows.

Many causes of male infertility may have considerable congenital implications for the children of such patients. Sixty percent of men with congenital bilateral absence of the vas deferens were shown to have one or more of the cystic fibrosis genes. The use of ICSI in these circumstances should be considered carefully, and men must be screened with the appropriate tests before treatment.

In order to give adequate counselling to couples and their families, genetic tests should be performed before, during or after ART in cases such as women with Turner’s syndrome, men with 47XXY, men or women with structural chromosomal aberrations, and men with either Yq11 deletion or congenital bilateral absence of the vas deferens (ESHRE Capri Workshop Group 2000).

The couple must be well informed about the treatment options that are suitable for them, the indications for the tests they have to undergo, details of the proposed treatment and its success rate, and risks and complications.

Normal folliculogenesis

This involves several important and inter-related steps.

Follicular development beyond the antral stage depends on the concentration of FSH in the circulation. Once a threshold level has been attained, follicular growth beyond 4 mm occurs. The interval during which FSH remains elevated above the threshold level can be regarded as a window through which a follicle must pass to avoid atresia. The width of the window will therefore determine the number of follicles that can be selected for ovulation (Figure 22.2). The preovulatory luteinizing hormone (LH) surge is triggered by the positive feedback of oestradiol from the dominant follicle, as well as other follicular contributory factors. Ovulation occurs 24–36 h after the onset of the LH surge.

Figure 22.2 (A) Selection and maturation of the dominant follicle (DF) during a natural cycle. (B) Induced follicle maturation with gonadotrophin therapy over-riding selection of a single dominant follicle, as in the natural cycle. hCG, human chorionic gonadotrophin.

Pituitary downregulation

In the conventional ART protocol, it is standard practice to use a continuous and supraphysiological dose of GnRH agonist to obtain control over the hypothalamic–pituitary–ovarian axis. GnRH agonists cause an initial flare response, characterized by increased gonadotrophin secretion, due to upregulation of GnRH receptors. However, prolonged administration of GnRH agonists induces downregulation of GnRH receptors. This prevents a premature surge in LH and subsequent spontaneous ovulation with luteinization, which occurs in up to 23% of cycles when gonadotrophins alone are used and facilitates the timing of oocyte retrieval. The use of GnRH agonists in ART has been shown to increase the number of oocytes retrieved, improve the pregnancy rate and significantly reduce the chance of cycle cancellation (Hughes et al 1992).

Two different GnRH agonist protocols are used in most assisted conception units: long and short protocols. In the long protocol, GnRH agonists (buserelin or nafarelin) are started in the mid-luteal phase (day 21) of the previous menstrual cycle to achieve pituitary downregulation in approximately 8–21 days, after which gonadotrophins are commenced. GnRH agonists are administered for approximately 10–14 days in the short protocol. In both regimens, GnRH agonists are administered daily until the day of hCG or LH injection to trigger oocyte maturation. The short protocol takes advantage of the initial flare effect, which can be utilized to augment the ovarian response to gonadotrophin stimulation. However, a systematic review of 26 randomized-controlled trials found an increased clinical pregnancy rate per cycle and fewer cycle cancellations with the long protocol compared with the short protocol (Daya 2000). Therefore, the long GnRH agonist protocol is generally recommended in most ART cycles.

Use of the long GnRH agonist protocol often prolongs the stimulation phase, resulting in increased requirement for gonadotrophins and increased treatment cost in addition to causing undesirable side-effects of hypo-oestrogenism. It may also be associated with poor response in some patients, as well as introducing a higher risk of ovarian hyperstimulation syndrome (OHSS). Some of the disadvantages can be obviated with the use of GnRH antagonists, such as cetrorelix and ganirelix. GnRH antagonists induce immediate pituitary downregulation by competitively binding to GnRH receptors, and avoid the flare effects or the need for prolonged treatment associated with GnRH agonist protocols. Two different regimes have been described. The multiple-dose protocol involves the administration of 0.25 mg cetrorelix or ganirelix daily from day 6–7 of stimulation, or when the leading follicle is 14–15 mm, until hCG/LH administration. The single-dose protocol involves the single administration of 3 mg cetrorelix on day 7–8 of stimulation. GnRH antagonist protocols are therefore short and simple, but more importantly they reduce the incidence of severe OHSS. However, the clinical pregnancy rates following IVF treatment were significantly lower with GnRH antagonist use compared with the long GnRH agonist protocol [odds ratio (OR) 0.82, 95% confidence interval (CI) 0.68–0.97] (Al-Inany et al 2007), although data from units with experience of the GnRH antagonist protocol are encouraging. More recent trials of GnRH antagonists have reported better pregnancy rates than earlier trials, which used antagonist protocols that would now be recognized as suboptimal.

Controlled ovarian stimulation

The pregnancy rate with unstimulated IVF remains much lower than that in stimulated cycles, achieving a livebirth rate of 2.3% per initiated cycle and 4.7% per ET (Human Fertilisation and Embryology Authority 2000). These results have remained low over the past decade. Although an unstimulated cycle is simpler, faster, less painful, less expensive and has no risk of ovarian hyperstimulation, it requires relatively extensive monitoring which increases the cost and results in inconvenience in the timing of oocyte retrieval. Additionally, women with irregular cycles and/or hormonal imbalance or couples with male factor infertility, where fertilization may be a problem, are not suitable for natural-cycle IVF. The aims of superovulation regimens in assisted reproduction are to maximize the number of follicles that mature, to minimize the degree of asynchrony amongst developing follicles, and to minimize the deleterious effects of the abnormal follicular environment on luteal function and endometrial receptivity. Multiple follicular development and ovulation can be achieved by widening the FSH window. Several drug combinations have been used to achieve this.

Oocyte retrieval may be programmed to coincide with a working day by manipulating the onset of the menstrual cycle using norethisterone tablets, the combined oral contraceptive pill, or utilizing the hypogonadotrophic effect of GnRH agonists prior to commencing gonadotrophins on a predetermined day of the week. The downregulatory phase may be prolonged to allow a fixed number of patients to be treated each week. In the long GnRH agonist protocol, gonadotrophins are commenced following the confirmation of ovarian suppression, characterized by a thin endometrium of 5 mm less than transvaginal scan and a serum oestradiol level of less than 200 pmol/l.

The first commercially available gonadotrophin preparation used in superovulation protocols, human menopausal gonadotrophin (HMG), was extracted from the urine of menopausal women. The initial preparations were shown to be of low purity, and the major protein components were not gonadotrophins; only 5% constituted FSH and LH activity. The repeated injection of non-gonadotrophin proteins may be the cause of unwanted effects, such as pain and allergic reactions. The desirability for high-purity preparations led to the development of an immunopurified FSH product with more than 95% purity following the removal of LH activity from HMG. The introduction of highly purified urinary FSH was associated with much reduced hypersensitivity, enabling administration via the subcutaneous route. The currently available commercial preparation of HMG is also highly purified and contains both FSH and LH activity at a ratio of 1:1. The LH activity in HMG is partly due to the presence of exogenous hCG, which is added to correct imbalances in the FSH/LH ratio.

Genetic and molecular engineering has led to the production of recombinant human FSH (rFSH) with high purity (>99%), high specific bioactivity (>10,000 IU/mg protein) and absent intrinsic LH activity which is suitable for intramuscular or subcutaneous administration (Mannaerts et al 1991). Two different rFSH preparations are commercially available: follitropin alpha (Gonal F) and follitropin beta (Puregon). These two rFSH preparations differ in that follitropin alpha has a more acidic isoform profile than follitropin beta due to a slight difference in its carbohydrate component. Consequently, they differ in metabolic clearance, half-life and biological activity, but both are equally effective during ART cycles in terms of livebirth rates. A number of well-designed randomized-controlled trials have compared both preparations of rFSH against HMG in their clinical effectiveness during conventional IVF with the long GnRH agonist protocol. While none of them individually showed any statistically significant difference in livebirth rates between the two treatment arms, two recent systematic reviews have demonstrated a significant 4% increase in livebirth rate in the HMG arm (Al-Inany et al 2008, Coomarasamy et al 2008). However, the results of the meta-analysis need to be interpreted with caution because of the clinical heterogeneity of the trials; therefore, a large multicentre randomized double-blind trial is warranted. Moreover, such studies should consider reporting the more clinically relevant cumulative livebirth rates as the primary outcome.

Recombinant DNA technologies have also made it possible to produce LH (rLH). Due to the potential role of LH in follicular development according to the two-cell theory of gonadotrophin system, supplemental rLH has been suggested to improve IVF outcome if rFSH is used for ovarian stimulation. However, a recent systematic review of randomized trials failed to demonstrate any difference in livebirth rates with adding rLH to the rFSH protocol (Kolibianakis et al 2007). Although it is possible that rLH supplementation may be beneficial in a subset of the IVF population, such as poor responders (Mochtar et al 2007), its generalized use is currently limited.

The collective evidence from many studies suggests that 150–225 IU/day gonadotrophin is the appropriate starting dose for most women undergoing conventional IVF treatment. The majority of units use a daily dose according to women’s age and the presence or absence of polycystic ovaries: 150 IU in women under 30 years of age or with polycystic ovaries, 225 IU for those between 30 and 39 years of age, and 300 IU for those aged 40 years or over. The lowest possible dose to achieve the optimum ovarian response should be used to reduce the risks of ovarian hyperstimulation. Although there is no consensus on what constitutes optimum ovarian stimulation, a recent study has reported that the implantation rate is maximum when 10 oocytes are retrieved following conventional IVF using the long downregulation protocol (Verberg et al 2009a).

Recently, mild ovarian stimulation protocols have gained a lot of interest in the field of ART, with the current trend of limiting the number of embryos transferred reducing the need for large numbers of oocytes. The principal aim with this approach is to reduce the number of developing follicles and thereby minimize the adverse effects of ovarian stimulation, particularly OHSS and multiple pregnancies. Three reported mild stimulation protocols include clomiphene citrate alone or in combination with gonadotrophins, delayed commencement (day 5 of the cycle) of gonadotrophins with GnRH antagonist co-medication, and late follicular replacement of FSH with administration of hCG/LH (Verberg et al 2009b). All of these protocols have been shown to reduce the gonadotrophin dosage and have the potential to reduce the cost of treatment and patient distress associated with conventional ART. As expected, the ongoing pregnancy rates/livebirth rates per cycle have been lower compared with the conventional protocol, but similar effectiveness could be achieved with more treatment cycles.

Monitoring follicular development

The purpose of monitoring ovarian response is to ensure safe practice in reducing the incidence and severity of OHSS, and also to optimize the timing of luteinization before oocyte retrieval. Ultrasound forms an integral part of monitoring. Follicular response together with endometrial thickness is monitored by ultrasound scans commencing on day 6–8 of the treatment cycle. Some units also measure serum oestradiol levels. However, current evidence does not support the adjuvant use of oestradiol for monitoring, as it does not give additional information with regard to livebirth rate or OHSS rate. The gonadotrophin dosage is adjusted according to ovarian response, although the evidence for this practice is limited. Typically, follicles are noted to grow at a rate of 2–3 mm/day, accompanied by a steady increase in serum oestradiol levels. When three or more follicles are 18 mm or greater in diameter, 5000–10,000 U hCG or 250 µg choriogonadotropin alpha (recombinant preparation) are given subcutaneously to induce oocyte maturation before oocyte retrieval.

Ovarian response is poor when no follicles or less than three follicles develop after 14 days of gonadotrophin treatment; this generally results in cancellation of the stimulation cycle. This problem is frequently encountered in women with reduced predicted ovarian reserve. Conversely, excessive ovarian response may result in OHSS, which will be discussed later. Other problems such as a premature LH surge or preoperative ovulation have been largely eliminated by the introduction of GnRH analogues in superovulation protocols.

Equipment and preparation

Oocyte retrieval is performed 36 h after the trigger injection of hCG/LH. Methods of egg collection have improved considerably since the introduction of ART. At first, all egg collections were performed laparoscopically. This is now rarely used and is reserved for women whose ovaries are inaccessible through the transvaginal route. With the introduction of endovaginal transducers, the transvaginal-ultrasound-guided approach became the predominant method for egg collection. In this, the specially designed transducer is used to visualize the follicles and the aspirating needle is passed alongside it. This method is generally well tolerated when carried out under light intravenous sedation, can be learnt very quickly and is associated with minimal morbidity.

Technique

Several types of aspiration needle are available. They may have a single or double lumen to enable aspiration and flushing through different routes. The needle is usually 16-guage and must have a very sharp tip to enable easy puncture of mobile ovaries; the distal 2 cm should be roughened to enhance ultrasound visualization (Figure 22.3). The needle is connected to a test tube by tubing, and suction is applied either from a foot-operated pump (Figure 22.4) or manually. The ultrasound transducer (Figure 22.5) is enclosed in a special sterile condom and plastic sleeve prior to insertion into the vagina, and should be cleaned thoroughly with a damp cloth after each procedure.

Figure 22.3 Ultrasound picture during vaginal egg recovery. The tip of the needle (arrow) is seen within the follicle (F).

Figure 22.4 Follicle aspiration equipment. An assembled follicle aspiration needle with a single lumen is connected to a test tube. The test tube is, in turn, connected to a suction pump. The needle is attached to the transvaginal ultrasound transducer through needle guide and bracket.

Figure 22.5 Vaginal ultrasound transducer enclosed in a sterile condom with needle guide attached. The needle tip is protruding from the proximal end of the probe.

Generally, very few technical difficulties are encountered during vaginal egg collection. The main risks of transvaginal oocyte recovery are pelvic infection (0.6%) and bleeding (>100 ml in 0.8% cases) (Bennett et al 1993), which may be serious, sometimes even fatal. Appropriate preoperative vaginal preparation and minimizing the number of repeated vaginal penetrations may serve to lower the risk of infection. While there is no evidence that routine antibiotics reduce the risk of infection, the administration of an intravenous bolus of antibiotic is generally recommended for women with a history of severe pelvic inflammatory disease or if an endometrioma is punctured. Intestinal, vascular, uterine and tubal injuries with the aspiration needle have also been reported. Bleeding and infections may be serious, sometimes even fatal, complications.

Female age

The woman’s age at the time of treatment is an important prognostic factor when the success of IVF is discussed with any couple. The number of oocytes and, consequently, the number of embryos decline with age. However, the cleavage rate does not seem to alter in the same manner. The number of embryos replaced compounds the effect of age and embryo implantation rates on pregnancy rate. The total number of embryos available for replacement influences this further. When a larger number of embryos is available for replacement, the selection of the most appropriate embryos for transfer improves the implantation and pregnancy rates.

Indeed, when women over 40 years of age had four or more embryos transferred, their pregnancy rate was not significantly different from that of younger women, whether following IVF (Widra et al 1996) or ICSI (Alrayyes et al 1997). Hence, it may be concluded that older women with a good ovarian response, producing three or more embryos suitable for transfer, have similar prospects for establishing a pregnancy as younger patients. However, other data support reduced implantation rates in older women, regardless of the number of embryos transferred (Piette et al 1990). Younger women, even if their ovarian response is poor, have a better implantation rate than women over 40 years of age experiencing a normal ovarian response (van Rooij et al 2003). This indicates that age is the major determinant of the implantation potential of oocytes and/or of endometrial receptivity. However, the reported finding of similar pregnancy rates in older women having treatment using donor eggs compared with younger women indicates that oocyte quality or implantation potential, rather than endometrial receptivity, declines with women’s age (Van Voorhis 2007).

Although livebirth rates per treatment cycle following IVF and ICSI have increased consistently over the past decade, they decline with advancing age of women when using their own eggs (Figure 22.9). A number of investigators have examined different age cut-offs such as 40 years (Widra et al 1996, Sharif et al 1998) or 35 years (Preutthipan et al 1996). Mardesic et al (1994) reported that the cut-off point of effectiveness for an IVF programme was 36–37 years, with a marked decline in pregnancy rate per ET in women over 38 years of age.

Figure 22.9 Livebirth rates by age of women who have in-vitro fertilization or intracytoplasmic injection. Success rates have improved over the years for all ages.

Source: Human Fertilisation and Embryology Authority (2008).

In an attempt to identify factors that affect the outcome of treatment, Templeton et al (1996) analysed the HFEA database between 1991 and 1994. They reported that the overall livebirth rate per treatment cycle was 13.9%. The highest livebirth rates were in women aged 25–30 years, with younger women (<25 years) having lower rates, and a sharp decline noted in older women. At all ages over 30 years, the use of donor eggs was associated with significantly higher livebirth rates compared with the use of the women’s own eggs, although there was equally a downward trend in success rates with age. After adjustment for age, increasing duration of infertility was associated with a significant decrease in livebirth rates. The indications for treatment had no significant effect on the outcome, while previous pregnancy and live birth increased treatment success significantly.

Miscarriage rates have been reported to be higher in all women following IVF, and there is a two- to three-fold increase in the rate of spontaneous abortion in women aged 40 years or more (Toner and Flood 1993). Embryo quality is more likely to be the main factor influencing the poor reproductive performance of women with advancing age than a defective response of the uterine vasculature to steroids or uterine ageing. Increasing maternal age correlates with a higher risk of fetal chromosomal aneuploidy, which results in an increased rate of miscarriage (Spandorfer et al 2004).

Obesity

Although the consequences of obesity for women’s fertility are well known, there is controversy regarding the effect of obesity on the outcome of IVF treatment. Overweight [body mass index (BMI) ≥25] and obesity (BMI ≥30) have been associated with the need for higher doses of gonadotrophins, increased cycle cancellation rates and retrieval of fewer oocytes. Lower rates of ET, pregnancy and live birth have also been reported, as have higher miscarriage rates (Fedorcsak et al 2004). Other studies have not found that obesity has a negative impact on ART outcome (Dechaud et al 2006, Sneed et al 2008). However, a recent systematic review of all the reported studies confirmed that obesity has an adverse effect on the success of IVF (Maheshwari et al 2007); therefore, obese women should be advised to lose weight before commencing ART in order to improve their chance of success.

Cause of infertility

Reports have differed in their analysis of the impact of infertility factors on cumulative conception and livebirth rates. While some have found significant differences, with the lowest rates being reported in patients with male infertility or multiple infertility factors (Tan et al 1992), others found no significant effect on outcome (Templeton et al 1996). However, a history of previous pregnancy and live birth increased treatment success significantly. The IVF clinical pregnancy and livebirth rates in the HFEA report of 2000 show similar results for tubal disease, endometriosis and unexplained infertility (Figure 22.10). Reports of higher fertilization rates after ICSI suggest that this technique may be better than the conventional method for all couples seeking IVF. A multicentre randomized-controlled trial comparing clinical outcome after ICSI or conventional IVF in couples with non-male-factor infertility showed higher implantation and pregnancy rates per cycle after IVF, hence supporting the practice of reserving ICSI for severe male factor infertility (Bhattacharya et al 2001).

Figure 22.10 Clinical pregnancy and livebirth rates following in-vitro fertilization for female causes of infertility.

Source: Human Fertilisation and Embryology Authority (2000).

All stages of endometriosis are viewed as suitable indications for ART. The timing of treatment is dependent on the severity of the disease, previous therapy and other factors, such as female age and duration of infertility. In women with severe endometriosis with mechanical tubal blockage and where surgery is inappropriate, IVF should be expedited. IVF should also be recommended 1–2 years after previous unsuccessful medical or surgical therapy, while in minimal or mild endometriosis, the balance of choice seems to be in favour of IVF after more than 2 years of expectant management. Initially, poor results were reported in women with severe disease (Matson and Yovich 1986). The introduction of ultrasound-guided techniques for oocyte collection resulted in the retrieval of more oocytes, and hence led to higher pregnancy and implantation rates in advanced-stage disease (Geber et al 1995). The use of GnRH agonists in stimulation protocols or as a pretreatment for women with endometriosis has also resulted in the retrieval and transfer of more preovulatory oocytes, lower cancellation of treatment cycles and a higher pregnancy rate, especially in women with advanced-stage disease. A recent meta-analysis indicated that the presence of ovarian endometrioma does not affect the quality of oocytes, as the pregnancy rate was similar to that of controls, although the ovarian response to gonadotrophins was reduced (Gupta et al 2006). While prospective randomized-controlled trials are lacking, evidence based on case–control studies suggests that surgery for bilateral endometrioma could impair IVF outcome significantly, possibly due to damage to the remaining healthy ovarian follicles (Somigliana et al 2008).

For male factor infertility, ICSI was successfully introduced in 1992 (Palermo et al 1992). Since then, the annual number of treatment cycles has increased steadily (see Figure 22.1). Previous techniques, such as partial zona dissection and subzonal insemination, were very disappointing (Cohen et al 1991), and comparative studies indicated that ICSI was much more efficient (Tarin 1995). It gave men who had previously been diagnosed with severe male factor infertility the chance to have their own genetic children. The sperm may be obtained either by ejaculation, percutaneous aspiration from the epididymis or testis, or testicular extraction, resulting in equally high fertilization, pregnancy and implantation rates, especially in men with borderline or very poor sperm quality. Recognized indications for ICSI include:

Livebirth rates following ICSI are shown in Figure 22.8. A remarkable change in fertilization rate with a significant increase in the percentage of two pronuclei oocytes occurred when the technique was modified slightly by breaking the sperm’s tail before injection (Fishel et al 1995). The technique requires a high-quality inverted microscope and special equipment, with holding and injection pipettes being used to stabilize and inject the oocyte, respectively. The injecting pipette is pushed almost entirely through the ooplasm before the spermatozoon is deposited inside the oocyte (Figure 22.11).

Figure 22.11 Intracytoplasmic injection of a single sperm (arrow) into the egg.

Duration of infertility

The duration of infertility remains one of the most important variables that influences the outcome of assisted reproduction, with lower pregnancy and livebirth rates associated with a longer period of infertility. Analysis of the HFEA database between 1991 and 1994 showed that, even with adjustment for age, there was a significant decrease in livebirth rate with increasing duration of infertility from 1 to 12 years (Templeton et al 1996).

Endometrial thickness

Endometrial thickness alone is a poor predictor for pregnancy. However, no conception has been recorded for endometrial thickness below 5 mm on the day of transfer. As such, it is recommended that consideration should be given to cryopreserving all embryos and preparing the endometrium with exogenous hormones in a subsequent cycle (Friedler et al 1996).

Number of embryos transferred

Regarding the optimum number of embryos to be transferred, there is a great deal of debate and a wide variation in practice across the world. Unarguably, ART is the single most important cause for the increase in multiple pregnancies over the last two decades, which is a direct consequence of the number of embryos transferred. Retrospective studies, as early as 1985, argued that multiple pregnancies and births increased with the increase in the number of embryos replaced (Wood et al 1985). Randomized studies comparing double ET with treble ET (Staessen et al 1993) or quadruple ET (Vauthier-Brouzes et al 1994) reported similar pregnancy rates, provided that there were sufficient morphologically regular embryos available for transfer. Analysis of the HFEA database of more than 44,000 cycles (Templeton and Morris 1998) and the HFEA reports (2000) showed that when four or more fertilized eggs were available, the transfer of three embryos did not result in improved pregnancy rates compared with the elective transfer of two embryos. However, the incidence of triplets or higher order multiple births decreased considerably when two embryos were replaced (Figure 22.12).

Figure 22.12 Live and multiple births following in-vitro fertilization when two or three fresh embryos were transferred after the creation of four or more embryos.

Source: Human Fertilisation and Embryology Authority (2000).

Despite only transferring two embryos during most IVF cycles, 40% of all IVF babies are twins (Human Fertilisation and Embryology Authority 2008). In order to deal with the unacceptably high multiple birth rates following ART, there is a recent move from the IVF community, particularly in Europe, to limit the number of embryos transferred to one in carefully selected patients. In the UK, the HFEA has set a target of reducing the multiple pregnancy rate to 10% over a period of about 3 years, and has urged the fertility clinics to devise a ‘multiple pregnancy minimization strategy’ to achieve the agreed target. To facilitate this, the British Fertility Society in unison with the Association of Clinical Embryologists in the UK have produced guidelines for practice which focus on the effectiveness of elective single ET (eSET) and patient selection for eSET (Cutting et al 2008). The two most important criteria when choosing a couple for eSET are female age and the quality of embryos available. Twin pregnancy has increased risk for the fetuses and the mother. Given the higher risks of premature delivery (three-fold), perinatal mortality (six-fold), cerebral palsy (four- to six-fold) and pregnancy complications (hypertension, pre-eclampsia, gestational diabetes etc.), and the consequent resource implications for the health service with twin births compared with singleton deliveries, the HFEA in the UK has urged for successful IVF to be redefined as ‘full-term singletons with a normal birth weight’ in order to promote eSET and thereby reduce multiple births (Cutting et al 2008). A Cochrane review comparing the outcome of double ET in a single cycle compared with eSET (combined with transfer of a single frozen–thawed embryo in a subsequent cycle if necessary) identified similar pregnancy rates in both groups (OR 1.19, 95% CI 0.87–1.62) with a substantially higher multiple pregnancy rate following double ET (OR 62.83, 95% CI 8.52–463.57) (Pandian et al 2005). Several European countries have now adopted eSET coupled with effective cryopreservation programmes in patients with a good prognosis, and have reported no significant difference in pregnancy rates but a significant reduction in the rate of twin pregnancies. In carefully selected patients (e.g. women <37 years of age, undergoing their first IVF cycle and with more than one top-quality embryo), eSET plus subsequent frozen embryo replacement can be as effective as double ET.

Number of attempts

The literature appears to be somewhat divided regarding pregnancy and livebirth rates in relation to the number of ART attempts. In one study (Padilla and Garcia 1989), the pregnancy rate per ET was similar for at least seven attempts, while other studies (Tan et al 1992, Templeton et al 1996) reported a decline in pregnancy and livebirth rates with successive treatment cycles. The data from the HFEA 2000 annual report show a steady decline in pregnancy and livebirth rates per cycle after the fifth attempt, being 11.1% and 8.6%, respectively, at the 11th attempt (Figure 22.13).

Figure 22.13 Livebirth rates by number of attempts following in-vitro fertilization.

Source: Human Fertilisation and Embryology Authority (2000).

When IVF cumulative pregnancy rates were estimated for a cohort of women, the rates showed a constant rise during the six initial IVF treatments and plateaued subsequently (Dor et al 1996). Similarly, the rates were reported to be as high as 80% after seven cycles, and a history of previous pregnancy improved a couple’s probability of conception significantly (Croucher et al 1998).

Embryo cryopreservation

The ability to cryopreserve embryos enables any supernumerary embryos to be stored for some time before subsequent replacement when fresh ET has failed or if further children are desired. Additionally, cryopreservation has the added benefit of increasing the number of potential embryo replacement cycles without the need to undergo superovulation and oocyte retrieval, hence reducing the risk of OHSS. Embryo quality has the most significant impact on post-thaw survival and, ultimately, pregnancy and implantation rates. As with fresh embryos, factors such as female age, number of embryos transferred and whether a pregnancy resulted from the original stimulation cycle will affect the outcome of the FER cycle.

In 2005, the HFEA annual register reported a clinical pregnancy rate of 18% and a livebirth rate of 15.6% per FER cycle in women using their own gametes (Human Fertilisation and Embryology Authority 2008). Over the past decade, considerable improvement has taken place. The French register (FIVNAT 1996) reported an increase in pregnancy rate per transfer from 11.5% to 16% between 1987 and 1995. It has been estimated that one FER cycle increases the ‘take-home baby’ rate by 5% (Kahn et al 1993), while treatment involving one fresh and two FER cycles achieves a cumulative viable pregnancy rate of 41% (Horne et al 1997). Frozen–thawed embryos can be replaced in natural or hormonally adjusted cycles utilizing GnRH agonist and oestrogen/progestogen preparations with comparable results. The use of GnRH agonist is useful in anovulatory or irregular cycles, and the use of different progestogens for luteal-phase support is equally effective. The cost per delivery for an FER cycle has been estimated to be between 25% and 45% of the cost of a fresh cycle. In view of these advantages, cryopreservation should be accessible and discussed with all couples where surplus good-quality embryos are available.

Oocyte donation

Oocyte donation is an effective treatment for women with premature ovarian failure, Turner’s syndrome, following oophorectomy, chemo- or radiotherapy-related ovarian failure, in certain cases where there is a high risk of transmitting a genetic disorder to the child, and where repeated failure of fertilization is attributed to poor oocyte quality. High pregnancy rates have been reported following oocyte donation for patients with Turner’s syndrome (Khastgir et al 1997). However, Turner’s patients were reported to have significantly higher biochemical pregnancy rates and early miscarriages, and lower clinical pregnancy and delivery rates compared with other women with premature ovarian failure (Yaron et al 1996). An important factor in the establishment of pregnancy is an endometrial thickness of greater than 6.5 mm. Other factors include the number of previous natural conceptions and live births, and the fertilization rate, while increasing female age does not affect the outcome (Burton et al 1992).

The HFEA recommends that the age limit for egg donors should be 35 years, except in exceptional circumstances. This is because there is an increased pregnancy rate and reduced risk of aneuploidy in the offspring if the treatment is performed using eggs from young donors. Oocyte donors are screened for infections (human immunodeficiency virus, hepatitis B, hepatitis C and cytomegalovirus, Venereal Disease Research Laboratory tests for syphilis), genetic diseases such as cystic fibrosis, and major chromosomal anomalies. Targeted screening based on ethnic background is also recommended: for example, Tay–Sachs disease for Jewish population, sickle cell screening in Afro-Caribbean population and thallassaemia in Asian population. If the prospective donor is found to be heterozygous for cystic fibrosis, the partner of the recipient should also be screened for cystic fibrosis.

Oocyte donation has considerable emotional and social effects on both the donor and the recipient, more so if the donor is undergoing IVF treatment herself. Both the recipient and the donor should have counselling from someone who is independent of the treatment unit regarding the physical and psychological implications of treatment for themselves and their genetic children, including any potential children resulting from donated oocytes. Apart from anonymous and known oocyte donation, an egg share scheme is an efficient use of oocytes. This aims to reduce the imbalance between the large number of potential recipients and the small number of available donors. This also allows women requiring IVF and with insufficient funds for their own treatment to access IVF treatment for free or at a significantly reduced cost. Many studies have reported a safe ‘cut-off’ number of oocytes to be collected from the egg share donor to share with the recipient.

Livebirth rates following treatment using oocyte donation are excellent. Pregnancy and livebirth rates per treatment cycle following oocyte donation in comparison with other treatments are depicted in Figure 22.14 where fresh embryos are replaced, and in Figure 22.15 where frozen–thawed embryos are replaced (Human Fertilisation and Embryology Authority 2008). Neither the recipient’s age nor the indication of treatment affects the success of oocyte donation substantially. However, pregnancy resulting from oocyte donation should be considered as high risk, especially in those with ovarian failure, because of an increased incidence of small-for-gestational-age infants. Oocyte recipients should also be counselled regarding their increased risk for pregnancy-induced hypertension and postpartum haemorrhage.

Figure 22.14 Clinical pregnancy and livebirth rates following in-vitro fertilization with fresh embryo-transfer-stimulated cycles, performed in 2005.

Source: Human Fertilisation and Embryology Authority (2008).

Figure 22.15 Clinical pregnancy and livebirth rates following in-vitro fertilization with frozen embryo replacement, performed in 2005.

Source: Human Fertilisation and Embryology Authority (2008).

Ectopic pregnancy

The first pregnancy following IVF was an ectopic pregnancy. There is a higher rate of ectopic pregnancy after IVF/ICSI treatment, principally due to the high prevalence of tubal factor infertility. The obstetric risks and outcomes of ART have always been the subject of considerable debate. Between 2% and 5% of ART pregnancies have been reported to be ectopic and 0.1–0.3% have been reported to be heterotopic (Clayton et al 2006). For comparison, the prevalence of ectopic pregnancy and heterotopic pregnancy following natural conception is approximately one in 100 and one in 30,000 respectively. The overall ectopic pregnancy rate per treatment cycle was 0.3% of over 467,778 IVF/ICSI cycles performed in the UK from 1991 to 2005 (Human Fertilisation and Embryology Authority 2008).

Ovarian hyperstimulation syndrome

OHSS remains the most serious and potentially lethal complication of ovarian hyperstimulation, correlates positively with conceptual cycles and is almost exclusively related to either exogenous or endogenous hCG stimulation. The pathophysiology of OHSS is characterized by increased capillary permeability, mediated by the vasoactive substances released from the hyperstimulated ovaries. Fluid leaks from the intravascular compartment into the third space, causing intravascular dehydration and, in severe cases, multisystem dysfunction. Young age, presence of PCOS, lean body mass and previous history of OHSS have all been reported to be risk factors for the development of OHSS. The risk increases with excessive ovarian response to gonadotrophins, characterized by the development of a large number of follicles including immature and intermediate follicles and/or high serum oestradiol levels. Mild forms are common, affecting up to 33% of IVF cycles. The overall prevalence of moderate-to-severe OHSS varies from 3% to 8% of IVF/ICSI cycles (Mathur et al 2007). The time of onset of OHSS may determine the prognosis; late-onset OHSS is likely to be more severe and to last longer than early-onset OHSS. Early-onset OHSS is due to the effects of exogenous hCG and presents within 9 days of the ovulatory trigger hCG. Endogenous hCG from an early pregnancy triggers the development of late-onset OHSS, which develops 9 days after the ovulatory hCG.

Prevention and early recognition are the two most important components in the management of OHSS. The key to prevention is proper identification of the population at risk before treatment, and close monitoring of hormone levels as well as follicular response on ultrasound (Figure 22.16). When a high-risk situation is recognized, withholding the ovulatory dose of hCG and cancellation of the treatment cycle will almost certainly prevent OHSS. The couple should be advised to avoid intercourse as spontaneous ovulation may occur up to 11 days after discontinuing gonadotrophin treatment, resulting in conception and development of severe OHSS.

Figure 22.16 Vaginal ultrasound appearance of the hyperstimulated ovary. The enlarged ovary contains an excessive number of large, intermediate and small follicles.

Alternative strategies have been attempted and, when effective, they usually ameliorate the severity of OHSS rather than prevent it absolutely (see Box 22.2).

A diagnosis of OHSS is usually straightforward, with typical symptoms of abdominal distension, abdominal pain, nausea and vomiting, reduced urine output and breathing difficulties. Women with OHSS should have the severity of their condition assessed (RCOG 2006). Treatment of established OHSS depends on its severity, the stage at which the diagnosis is made and whether or not the patient is pregnant. In mild cases and most moderate cases of OHSS (haematocrit <45%), bed rest, simple analgesia, increased fluid intake and close monitoring of electrolyte balance may be sufficient. Women should be encouraged to drink to thirst, rather than to excess. The patient’s progress can be supervised on an outpatient basis. Hospital admission should be recommended to some women with moderate OHSS and all those with severe OHSS (haematocrit ≥45%, massive ascites). Women should be kept under review until resolution of the condition. Inpatient management is mainly aimed towards preventing or alleviating haemoconcentration, renal hypoperfusion and thromboembolic phenomena. Initiation of intravenous fluid is not always necessary unless oral intake cannot maintain renal perfusion and function. Analgesics and antiemetics should be instituted for symptomatic relief, along with subcutaneous heparin for antithrombotic prophylaxis. Diuretics should not be used in women with oliguria secondary to a reduced blood volume and decreased renal perfusion, as they may worsen intravascular dehydration. Paracentesis may be necessary for symptomatic relief or failing renal function as it results in a dramatic improvement in clinical symptoms, diuresis and improved creatinine clearance (Aboulghar et al 1992). Multidisciplinary input including critical care may be required for women who develop severe complications such as severe ascites, liver or renal dysfunction, thromboembolism or adult respiratory distress syndrome.

Risk of genital and breast cancer

The potential risk of genital cancer from follicular stimulation has initiated considerable debate (Brinton 2007). While the results of earlier studies were alarming, subsequent studies with much longer follow-up periods and better designs showed reassuring results. In a cohort study of 12,193 women, Brinton et al (2004) reported no increased risk associated with clomiphene or gonadotrophin use among subjects who had been followed-up for a median of 18.8 years. Subsequent larger studies concentrating on the effect of exposure to drugs used during IVF rather than those prescribed in earlier times also reported reassuring results (Venn et al 1999, Klip et al 2003). However, the average follow-up period in these studies was only 6–7 years. Therefore, long-term follow-up data are needed to fully evaluate the risk of exposure to gonadotrophins during IVF. Moreover, appropriate control groups should be used to determine whether the link is causal, as it is difficult to distinguish the effect of fertility treatment from that of infertility per se on the development of malignancies.

It is well established that endometrial cancer is sensitive to oestrogen, which is produced excessively during ovarian hyperstimulation. Most smaller cohort studies have not found any association between the fertility drugs and endometrial cancer, but the follow-up period in these studies has been less than 10 years (Brinton 2007). In a larger series with an average of over 20 years of follow-up, a significant two-fold increase in endometrial cancer was associated with ovulation induction agents (Modan et al 1998). However, this study evaluated women who had undergone fertility treatment between 1964 and 1974, and therefore these results cannot be extrapolated to modern-day IVF treatment.

Concerns relating to the effect of high oestrogen and progesterone levels on the potential risk for the development of breast cancer have also been expressed. A large cohort study of over 90,000 subjects showed no association between exposure to ART and breast cancer (Gauthier et al 2004).

In summary, the effects of ovulation induction agents currently used in ART on genital cancer risk are unclear. Considering that the treatment protocols, preparations and dosages used during IVF are relatively new, and women exposed to IVF are only beginning to reach the cancer age range, further follow-up studies are required in this area.

Risk of congenital anomalies and malignancy in the newborn

Since IVF and ICSI became common fertility treatment modalities, concerns have been raised regarding the risk of major congenital malformations in children born following these treatments. While the majority of studies have shown an increased risk of major anomalies compared with spontaneously conceived pregnancies, some studies have been reassuring. A recent meta-analysis of 25 studies concluded that there is a statistically significant increase (30–40%) in birth defects compared with background risk (Hansen et al 2005). The authors expressed this result in terms of the number needed to harm, which in this case equates to the number of children that need to be conceived by ART for one additional child to be born with a birth defect. Therefore, for an underlying prevalence of birth defects between 1% and 4% of all births, the number needed to harm is between 250 and 62 treatments. ICSI enabled men with severe oligospermia or azoospermia to pass their genes on to their own progeny; an event that may not have been possible a few years ago. This raises certain questions about the genetic constitution of any resulting pregnancies after ICSI. A 1.2-fold increased risk of major birth defects in children born after ICSI (95% CI 0.97–1.28) compared with IVF was noted in a systematic review of the reported studies (Lie et al 2005). Sons of infertile males with Y chromosome microdeletions and born following ICSI treatment may inherit the same abnormality and are likely to be infertile.

The increased risk of congenital malformations in ART children may largely be due to the underlying parental background, rather than the treatment techniques themselves. In a recent comparative study of malformation in children born to fertile (time to pregnancy interval of ≤12 months) and subfertile parents (time to pregnancy interval of >12 months), the overall prevalence increased with increasing time to pregnancy. Compared with children in the fertile group, singletons born to infertile couples had a higher rate of congenital malformations regardless of whether they were conceived naturally (OR 1.20, 95% CI 1.07–1.35) or after infertility treatment (OR 1.39, 95% CI 1.23–1.57) (Zhu et al 2006).

There have been concerns regarding increased risk of rare imprinting disorders such as Beckwith–Wiedemann’s syndrome and Angelman’s syndrome in children following ART. However, the data are inconsistent, with some studies reporting increased frequency in ART children (Sutcliffe et al 2006) and other studies not finding any association (Bowdin et al 2007). Due to the rarity of these conditions, much larger studies are required for reliable detection of such associations.

Risk of malignancy in children

The issue of childhood cancer among children born after ART has been addressed in a few studies. An increased prevalence of retinoblastoma and Langerhan’s histiocytosis among children born after ART in comparison with the general population has been reported in two separate studies (Moll et al 2003, Kallen et al 2005). However, the overall risk of cancer and the individual incidence of all other recorded cancers were no greater than that in the general population (Kallen et al 2005). As childhood cancers are rare, larger studies are required for reliable evaluation of any increase in risk amongst ART children.

In the context of pregnancy outcomes, the aim of ART should be a healthy singleton delivery at term. However, infertile couples may not share this target. They do not appreciate the risks associated with multiple pregnancy; indeed, between 67% and 90% of couples may desire a twin birth, while less than one-third of couples regard a single child as an ideal outcome. Increasing age or duration of infertility has been associated with greater desire for multiple births (Murdoch 1997). As discussed earlier in this chapter, an increased multiple pregnancy rate is a major reason for the increased adverse obstetric and perinatal outcomes associated with ART.

Antenatal and intrapartum complications following assisted reproduction

Many studies have examined obstetric outcomes after fertility treatment. The risk of spontaneous miscarriage appears to be higher among ART pregnancies than among the general population. This comparison can be misleading as ART pregnancies are commonly under intense surveillance; losses from a very early stage of pregnancy are often carefully documented and reported, whereas miscarriage rates among natural conceptions are extremely difficult to measure and can be easily underestimated. However, a large prospective study with a meticulously chosen control group concluded that the risk of spontaneous abortion may be increased by 20–34% in ART pregnancies compared with natural pregnancies after adjusting for differences in maternal age and previous spontaneous abortion (Wang et al 2004). However, this increased risk may be as a result of infertility itself rather than due to ART, as there was no difference in miscarriage rates between patients who achieved pregnancy following any fertility treatment, including ART, and those who conceived naturally while waiting for fertility treatment (Pezeshki et al 2000).

Comparison of obstetric outcomes of IVF/ICSI pregnancies with matched normally conceived pregnancies showed a significantly increased incidence of premature delivery, intrauterine growth restriction, vaginal bleeding and hypertension requiring hospitalization, pre-eclampsia and caesarean births (Halliday 2007). The increased obstetric risk can be attributed to the high rate of multiple pregnancies in most cases. However, the risk of a more complicated pregnancy was found to be increased even when the ART twin and singleton pregnancies were compared with spontaneously conceived twins and singletons, respectively, in two separate meta-analyses, even after the subjects were matched for maternal age (McDonald et al 2005a,b). A similar conclusion was drawn in another systematic review with similar objectives (Helmerhorst et al 2004).

Pregnancy following ICSI treatment has generated interest due to the additional risks involved with these pregnancies, such as the microinjection technique and the use of testicular or epidydimal sperm. However, no significant difference in obstetric outcomes between IVF and ICSI pregnancies was noted, except for prematurity which was higher in IVF singletons (Ombelet et al 2005). Couples undergoing ICSI for severe male infertility (oligoasthenoteratozoospermia) have slightly reduced fertilization rates, but have similar rates of pregnancy loss and other obstetric outcomes as other couples undergoing ICSI and IVF for non-male-factor infertility (Mercan et al 1998).

Women who conceive following oocyte donation, especially those with a history of ovarian failure, should be considered as high risk. While the majority of oocyte recipients experience a favourable outcome, an increased rate of obstetric complications in these pregnancies has been reported by many investigators (Soderstrom-Anttila 2001). Pregnancy-induced hypertension appears to occur more often than expected, even among young recipients (Wiggins and Main 2005), and the caesarean section rate is high.

Embryo cryopreservation and obstetric outcome

Cryopreservation of embryos has no apparent negative effect on obstetric outcomes. The results were comparable in pregnancies following transfer of frozen embryos derived from IVF or ICSI. However, the frozen ICSI group showed a significantly higher miscarriage rate than the frozen conventional IVF patients in one study (Aytoz et al 1999).

Perinatal outcome of assisted reproduction pregnancies

It is widely accepted that the increased incidence of multiple pregnancies following ART accounts for a disproportionately large share of adverse perinatal outcomes, including the increased incidence of very low birth weight, low birth weight, perinatal and neonatal mortality, and infant death. The increased incidence of death and morbidity in twin pregnancies compared with singleton pregnancies has been attributed mainly to prematurity and to adverse outcomes associated with premature delivery, such as hyaline membrane disease, hypocalcaemia, hypoglycaemia, hyperbilirubinaemia, small for gestational age and low Apgar scores. Slotnick and Ortega (1996) suggested that monoamniotic multiple gestations may be increased in zona-manipulated cycles (ICSI, zona drilling, assisted hatching), and although all resulting monoamniotic pregnancies ended in live births, there was a high incidence of intrauterine discordance in fetal growth. Even when compared with matched control spontaneous twin pregnancies, ART twin pregnancies had low birth weights and needed more neonatal intensive care (Helmerhorst et al 2004). However, twins conceived with IVF/ICSI have comparable perinatal mortality and morbidity rates to spontaneously conceived controls (McDonald et al 2005a).

Elimination of multiple pregnancies will not eliminate the increased risk of adverse perinatal outcomes in ART. While twins born from assisted conception are not significantly disadvantaged compared with spontaneous twin pregnancies, ART singletons have a worse perinatal outcome compared with other singletons (Helmerhorst et al 2004). Singletons born from ART are at risk for lower mean birth weight and small for gestational age. Perinatal mortality appears to be significantly higher, even after matching for maternal age, parity and infant gender. ICSI treatment does not appear to differ from conventional IVF when perinatal outcomes are compared. Retrospective comparison of births resulting from cryopreserved embryos with those after conventional IVF and fresh ET showed no difference in perinatal mortality between the two groups (Wada et al 1994).