Pregnancy and antenatal care

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chapter 54 Pregnancy and antenatal care

INTRODUCTION AND OVERVIEW

General practitioners see patients throughout their life cycle, and integrative healthcare begins before conception and continues throughout pregnancy. Depending on your practice environment, you may be the sole practitioner responsible for the patient’s antenatal care as a GP/obstetrician, part of the antenatal shared care team including hospital-based midwives and an obstetrician, or see the patient for preconception advice, and then less frequently during the pregnancy if the patient is seeing an obstetrician for their antenatal care through personal preference or medical best practice.

PRECONCEPTION COUNSELLING

Comprehensive pregnancy care begins with the first discussion of conception, particularly for nulligravida. Ideally this consultation should occur 6–12 months before starting to attempt to conceive.

It may take the form of a formal preconception consultation, or begin with opportunistic questioning by the GP at the routine check-up of a woman of childbearing age (approximately 15–49 years), such as:

• Are you planning a pregnancy at some time in the future?
• Are you currently using contraception?
• How many babies do you think you will have?
• What spacing do you anticipate?
• What is your expected timing?

Enquire about previous pregnancies and the outcomes, including infant death, fetal loss, birth defects, low birth weight, preterm birth, or gestational diabetes or other maternal complications.

Chronic medical conditions such as diabetes need to be fully assessed and management optimised.

Immunisation status needs to be checked, particularly for preventable infectious diseases likely to affect a pregnancy, such as rubella, varicella, hepatitis B and measles. If non-immune, rubella and varicella immunisation need to be given at least 28 days before planned conception.

Influenza vaccination can be given at any time in pregnancy, particularly if the second or third trimester falls in influenza season.

Diphtheria/tetanus/pertussis combined vaccine should be given if a booster dose is due. This helps to protect the newborn from pertussis before they are old enough to have their immunisations.

Investigations might include:

• full blood examination and blood group
• iron studies
• serology for rubella, varicella, hepatitis B and measles immunity
• HIV status
• folate
• urine protein
• urinary iodine
• blood glucose
• vitamin D.

The genetic history should explore any congenital abnormalities in the extended biological family and, if necessary, genetic counselling arranged.

An important principle to remember is that any investment in the mother’s wellbeing—and the wider family, for that matter—is an investment in the wellbeing of the pregnancy and the future of the child. Preparation for pregnancy needs to address the woman’s physical, emotional and spiritual situation, including her beliefs about her relationship, parenting and lifestyle. It is helpful to consider the elements using the ESSENCE model, as discussed below (also see Ch 6).

EDUCATION

Planning a pregnancy is the time when women are arguably the most interested they have ever been in optimising their health, in the interests of having a healthy baby. It is also an opportunity to discuss the potential father’s lifestyle and general health. The advice provided at the preconception consultation may be the last chance to see the patient before she becomes pregnant, so this consultation needs to address issues that will be important in the early stages of pregnancy, even before she knows she is pregnant.

Women can be informed that the optimum biological age for pregnancy is between 20 and 35 years. Beyond that age, the risk of infertility, miscarriage, multiple pregnancy, pregnancy complications and fetal abnormalities increases statistically. However, many women are delaying conception until their late thirties and early forties, and deliver healthy babies.

Advice should include avoiding any prescribed or over-the-counter medications likely to affect early pregnancy, exercising regularly and avoiding alcohol, tobacco and illicit drugs. Any household members should be encouraged to stop smoking.

Preconception education will involve answering the questions posed, but also providing information to assist in optimising the health of the parents and opening a discussion about parenting ideas and philosophies.

STRESS MANAGEMENT

Because the mother’s stress hormones (including cortisol and catechols) cross the placenta, maternal stress also affects fetal neurological, physiological and metabolic development. For example, significant and prolonged maternal stress,1,2 particularly in the first trimester, is associated with poorer fetal growth, developmental problems, an increased risk of mental illness and a higher risk of cardiovascular disease in the offspring.

The work and home environment will have a significant impact on the potential mother’s stress levels.

Planning a pregnancy brings with it many anxieties about whether the woman will be able to become pregnant, inevitable life change, financial pressure, changes to career path and more. Information and an opportunity to talk through these concerns is helpful. Therefore, putting in place effective strategies for managing stress is an important part of preparing for pregnancy. Stress management activities such as regular sleep patterns, reducing reliance on substances and practising yoga, T’ai chi, meditation and relaxation exercises, as well as planning staged modifications to the mother’s work schedule, can provide benefits to emotional health. Counselling, cognitive behaviour therapy and mindfulness-based stress management may be helpful for some women where needed.

SPIRITUALITY

Starting a family affects a woman, her family and her work in profound ways. Asking about what all this means for her and how she will adjust may be an important conversation. A preliminary discussion of a patient’s religious or spiritual beliefs may be appropriate, particularly if there is a problem with fertility, if the pregnancy fails to proceed or if antenatal testing reveals a fetal abnormality.3 A discussion of the parents’ religious views about circumcision, should they have a male child, may be appropriate in the planning stages.

EXERCISE

Optimum fitness is a desirable goal prior to conception. Pregnancy adds a significant physical and physiological load, so aerobic and resistance training to help build fitness and muscle strength, and a back care program, will help her to cope with the pregnancy and childbirth far more effectively. She will also be able to reduce the risk of hypertension and diabetes during pregnancy, improve immunity and mental health and minimise complications. It should also be remembered that exercising to excess during pregnancy can be as much of a problem as being inactive.

Stretching and yoga improve flexibility. Patients with low back problems can be referred for back rehabilitation programs such as those supervised by physiotherapists or exercise physiologists.

Once the patient is pregnant, she can continue or adjust her current exercise program (Box 54.1).

BOX 54.1 Exercise advice for women with a normal pregnancy

• Swimming, walking and jogging are considered safe throughout pregnancy. Minimal contact sports such as tennis and netball are considered safe for at least the first 12 weeks and beyond, depending on the level of competition, the state of the pregnancy and the mother’s fitness level.
• Collision sports such as basketball and soccer are considered safe only up to 12 weeks, although there is no evidence that the type of impact that would occur from a sport-related collision or fall has ever injured an unborn baby.
• If a woman was not active before she became pregnant, she should start with gentle exercise such as walking or swimming.
• Assess whether there is any particular risk related to specific patients or their choice of sport(s). Refer to an exercise physiologist for specific advice.
• Review the training program regularly.
• Always work at less than 75% of the maximum heart rate (140 beats per minute or less, depending on the patient’s age).
• Patients need to know not to expect the same level of athletic performance when they are pregnant. They should stop exercising when tired and should avoid getting exhausted.
• Ensure a gentle cool-down period after strenuous exercise.
• Drink plenty of fluids and avoid getting over-heated.
• Advise patients to call you or their obstetrician urgently if they notice bleeding, abdominal pain or cramps, chest pain, oedema, dizziness, dyspnoea, insufficient weight gain or reduced fetal movements.

Activities to be avoided in pregnancy:

• gymnastics
• heavy weight-lifting
• horse riding
• martial arts
• mountain climbing
• parachuting
• saunas
• scuba diving
• trampolining
• water skiing

NUTRITION

Assess the patient for possible nutritional risk, especially if the patient is vegan, lactose-intolerant, has coeliac disease or other gut problems or an eating disorder likely to affect nutritional status. If the woman’s body weight is in the normal range, then dietary advice will focus on the quality and balance of foods she is eating.

However, women who are either significantly overweight or underweight need to address this risk factor. Obese women are 2.7 times more likely to be infertile than women in the healthy weight range. Obesity in women can also increase the risk of miscarriage and impair the outcomes of assisted reproductive technologies and pregnancy.4 It is also associated with an increased rate of caesarean section.5

Being underweight is associated with reduced conception rates among nulliparous women and increased likelihood of conception among parous women.6

Some foods are to be avoided because of the risk of listeriosis, which causes a risk of miscarriage. These foods include raw seafood, pre-prepared (salad bar) salads, delicatessen meats, leftovers, soft cheeses and pâté. All fruit and vegetables should be washed in filtered water before eating.

Eating a fresh, varied and healthy diet is important during pregnancy, as it is at any other time. Supplementation, particularly for those with poor vegetable intake, with a multivitamin containing 500 μg folate should commence prior to conception. Iron, zinc, vitamin D, calcium and iodine are all essential nutrients that may be lacking, and should be included in the choice of a high-quality antenatal supplement. A good intake of omega-3 fatty acids is also important for fetal development, and supplements of 3 g daily should be considered for those with a poor intake.

Some women think that ‘if one supplement is good, then more is better’. Check the contents of any supplements or over-the-counter preparations that are being taken, and be sure to avoid excess. This may particularly be the case for substances such as vitamin A.

CONNECTEDNESS

Relationships and social support are important not only for practical reasons but also because they have such a profound effect upon maternal emotional wellbeing and coping. Discuss the social connections the patient has with family and friends. Encourage development of a network of parents with babies, particularly if there are no family members likely to be around once the baby arrives.

ENVIRONMENT

The patient should be advised to avoid contact with household or occupational chemicals. Clear any toxic chemicals out of the house and replace with non-toxic alternative cleaning products.

If the family has a cat, advise that someone other than the pregnant (or intending to be pregnant) woman should empty the litter tray, to minimise the risk of toxoplasmosis. She should avoid contact with garden soil, wash all fruit and vegetables before consumption and avoid undercooked or raw meat or unpasteurised milk products. She should also limit the consumption of large fish likely to contain higher levels of mercury.

Discuss the potential for transmission of parvovirus B19 and cytomegalovirus. Childcare workers should wear gloves when changing children’s nappies and wash their hands frequently. Regular, moderate sun exposure will also be helpful for adequate vitamin D levels.

ANTENATAL CARE

Women suitable for shared antenatal care with their general practitioner (GP) include those defined as healthy women having a normal pregnancy. Complications usually requiring additional care by an obstetrician or other specialist are summarised in Box 54.2. Some of these women may still be suitable for shared care, with some modification of the usual schedule of visits.

BOX 54.2 Complications of pregnancy requiring specialist advice

• Cardiac (heart) disease, including hypertension (high blood pressure)
• Renal (kidney) disease
• Endocrine disorders or diabetes requiring insulin
• Psychiatric disorders (on medication)
• Haematological (blood) disorders, including thromboembolic disease
• Epilepsy requiring anticonvulsant drugs
• Malignant disease (such as cancer)
• Severe asthma
• Chemical dependency
• HIV positive
• HBV positive
• Autoimmune disorders
• Significantly overweight or underweight
• Significant environmental factors and lack of social support
• Recurrent miscarriage or mid-trimester loss
• Previous preterm delivery < 30 weeks of gestation
• More than five previous pregnancies (grand multiparity)
• Severe preeclampsia
• Rhesus isoimmunisation or other significant blood group antibodies
• Uterine surgery including caesarean section or cone biopsy
• Antenatal or postpartum haemorrhage on two or more occasions
• Retained placenta on two or more occasions
• Intrauterine growth restriction (IUGR)
• Stillbirth or infant (neonatal) death
• Birth weight < 2500 g, or > 4500 g
• Congenital abnormality, e.g. Down syndrome
• Postnatal depression or puerperal psychosis

Source: 3 Centres Collaboration7

SCHEDULE OF VISITS

The traditional schedule of antenatal visits was developed in the United Kingdom in the 1920s and consists of 14 visits based on first presentation early in pregnancy, monthly visits until 28 weeks’ gestation, fortnightly visits until 36 weeks’ gestation and weekly visits thereafter until delivery. Observational studies have demonstrated a beneficial effect of regular antenatal care on perinatal outcomes. Despite varying schedules, the overall aims of antenatal care can be summarised as described below.

• First trimester—from a carer’s perspective, the main aim of the first trimester antenatal visits is to identify potential risks to maternal and fetal wellbeing. The risk assessment includes careful history-taking, establishment of expected date of confinement, discussing illicit drug-taking, alcohol intake and smoking behaviour and establishing care options. Visits are usually timed to coincide with recommended screening tests where these occur at specific times, such as Down syndrome screening.
• Second trimester—the aim of second trimester visits is primarily to monitor fetal growth and maternal wellbeing, and monitor for early-onset preeclampsia. Routine tests in this trimester include an ultrasound for morphology at 18–22 weeks’ gestation and glucose screening at 24–28 weeks’ gestation.
• Third trimester—third trimester visits are primarily for the assessment of fetal growth and presentation, and of maternal wellbeing, detection of preeclampsia, and preparation of the woman for admission to the birthing facility and labour. Bacteriological screening for group B streptococcus takes place at around 35–37 weeks’ gestation.

Two reviews of the literature8,9 have suggested that reducing this schedule of visits to 10 is equally effective in achieving positive perinatal outcomes in low-risk gravidas, although it may be associated with a decrease in satisfaction with care. In particular, there was no difference in perinatal outcomes between primigravidas and multigravidas.

Early in her pregnancy, the woman should be given information regarding the schedule of visits and testing that she can expect. The number and timing of visits should be flexible, to suit her needs. Additional visits should be provided if complications arise.

MODELS OF CARE

Routine involvement of specialist obstetricians in low-risk maternity care is not associated with any improvement in perinatal outcomes compared to involving obstetricians when complications arise.9 Midwifery and GP-led models of care are safe for low-risk women. Women are more likely to be satisfied with their care where there is continuity of care, or carer. At each antenatal visit, midwives and doctors should offer information, consistent advice and clear explanations and provide the opportunity to ask questions.

INITIAL RECOMMENDED TESTS

• FBE including mean cell haemoglobin concentration (MCHC)/mean cell volume (MCV)—ferritin and thalassaemia screening by Hb electrophoresis is indicated on the basis of low MCV. Thalassaemia screening may also be indicated by family history or ethnicity. Women at risk of a severely affected fetus should be offered partner screening.
• Blood group/antibody screen—although Rhesus status may be known, a screen for antibodies should be performed in every pregnancy. Anti-Kell antibodies, for example, although rare (incidence approximately 0.5 per 1000), are associated with poor perinatal outcomes.10
• HIV antibodies (level 1 evidence)—the prevalence of HIV among pregnant women in Australia is unknown but has been estimated at 0.23 per 1000. It has been reported that 48% of Australian mothers whose children were exposed perinatally to HIV infection reported no other risk factors apart from heterosexual contact. Four interventions have been shown to significantly reduce vertical transmission rates: antiretroviral therapy to the pregnant woman and the child in the first 6 weeks of life; elective Caesarean section; avoidance of invasive obstetric procedures; and alternatives to breastfeeding. Evidence supports universal offering of HIV screening to pregnant women with appropriate pre- and post-test counselling.11
• Hepatitis B serology—vertical transmission of HBV can be prevented by prompt immunoprophylaxis at birth. Existing evidence supports screening at the first antenatal visit for hepatitis B surface antigen.
• Syphilis serology—congenital syphilis results in serious sequelae in liveborn infected children, and is also associated with long-term morbidity for women and increased pregnancy complications including non-immune hydrops. Although the prevalence of syphilis in the general population is low, universal screening programs have been shown to significantly increase the detection of syphilis in pregnant women compared with selective screening of those thought to be at high risk. In populations of high prevalence it may be repeated in the third trimester.
• Rubella immunity—pregnant women found not to be immune to rubella should be advised to avoid any potential risks, such as children with an unknown febrile illness. Vaccination should be given post partum.
• Asymptomatic bacteriuria (ASB)—routine screening between 12 and 16 weeks is recommended, to prevent urinary tract infections, preterm birth and low birth weight. Mid-stream urine for microscopy and culture is more sensitive than any other method and also more cost-effective in terms of outcomes. A full ward test may be used in addition to screening for chronic renal disease.
• PAP smear—if the woman is due and presenting in the first trimester.

OTHER TESTS TO BE CONSIDERED

• Hepatitis C—screening for hepatitis C by testing for HCV antibodies should be offered to all women at increased risk (Box 54.3). Unlike hepatitis B, however, universal screening has not been recommended from the point of view of antenatal care as the prevalence in the community is low, vertical transmission rates are low (6%) and there are no techniques to reduce vertical transmission rates. A positive HCV antibody test should be further investigated with HCV viral studies by polymerase chain reaction (PCR). Two negative PCR studies suggest that the patient is not a chronic carrier.
• Ferritin—iron deficiency is common in pregnancy, particularly in multigravidas or with a history of recurrent miscarriage. A ferritin of 50 (reference range 9–150) is thought to be adequate at the start of a pregnancy. Ferritin can be elevated in the presence of infection.
• Vitamin D—during pregnancy, sufficient vitamin D concentrations are needed not only to supply the growing demand for calcium on the part of the fetus, but also to participate in fetal growth, development of the nervous system, lung maturation and fetal immune system function. Hypovitaminosis D has been related to the development of fetal neurological and skeletal disorders. It is advisable for pregnant and lactating women to maintain adequate levels of vitamin D. If sun exposure is insufficient, which may be seen in darker-skinned women who have migrated to more temperate areas or through excessive covering up, supplements may be required.12
• Thalassaemia screen
• Dating ultrasound—a first-trimester ultrasound has been consistently shown to be more accurate than last menstrual period dates.

BOX 54.3 High-risk factors for hepatitis C

• History of injecting drugs (~40% of infected mothers)
• Partner who injected drugs
• Tattoo or piercing
• Been in prison (∼67% of women in prison)
• Blood transfusion, later positive for hepatits C
• Migration from a country with a high endemic rate

Other recommended tests

26 weeks

• Antibody screen
• FBE ± Fe studies
• Gestational diabetes screening—strategies for screening for gestational diabetes vary widely. Women are most commonly screened using a glucose challenge test, which does not require them to fast and consists of a single blood glucose 2 hours after the glucose load. If abnormal, this requires a full glucose tolerance test (GTT) for confirmation of the diagnosis. High-risk patients such as those with previous gestational diabetes should have the latter test only. Any suspicion that the woman may have undiagnosed prepregnancy diabetes requires investigation with a GTT in the first trimester; however, this does not replace the 26-week GTT, which should still be performed.

36 weeks

• Group B Streptococcus (GBS) screening—about 25% of pregnant women are thought to be carriers of GBS. Transmission to the newborn may occur during labour, resulting in pneumonia, septicaemia and, occasionally, mortality. The incidence of GBS disease is 1–3 per 1000 live births and can be reduced to 0.6 per 1000 live births by universal screening. The death rate for newborn GBS disease is estimated at 4.7–9%.13 Swabs should be taken between 35 and 37 weeks’ gestation. Recommendations for intrapartum prophylaxis are given in Box 54.4.

BOX 54.4 Recommendations for intrapartum antibiotics in prevention of GBS disease

Intrapartum antibiotics recommended if:

• < 37 weeks
• ruptured membranes > 18 weeks before delivery
• maternal temperature ≥ 38°C
• previous GBS colonisation, bacteriuria or infant with GBS

GBS is part of the intestinal flora. Treatment with oral antibiotics will not clear it from the bowel, and clearance from the vagina occurs spontaneously, as does the inevitable reinfection. The strategy is to provide chemoprophylaxis to the baby at the time that the baby is likely to come into contact with the organism.

• Repeat antibody screen for Rh-negative women unless the woman earlier received antenatal anti-D prophylaxis at 28 and 34 weeks’ gestation as the National Health and Medical Research Council recommends.14 If prophylaxis has been administered, the identification of passive anti-D from immunisation may cause confusion.

PRENATAL SCREENING FOR ANEUPLOIDY

Prenatal screening should be offered to all pregnant women irrespective of maternal age. Counselling should explore the woman’s current knowledge of chromosomal disorders. Most people are aware of the most common of the trisomies, trisomy 21 or Down syndrome. It should be emphasised that participation in screening is voluntary. The three commonly available screening tests—the first-trimester combined screen, nuchal translucency alone, and the second-trimester biochemical screening test or ‘quadruple test’—all give a ‘high risk’ or ‘low risk’ result rather than a definitive answer. Women should be made aware that they would be referred for genetic counselling following a ‘high risk’ result, with the option of having a subsequent invasive definitive test such as chorionic villus sampling or amniocentesis. Both of these invasive tests carry a risk of miscarriage of 1:100 or 1:200 respectively. The woman may elect not to have definitive testing. Following definitive testing, the woman could expect to receive further counselling about the result. A woman who has a diagnosis of aneuploidy confirmed may, after further counselling, be offered a termination of the pregnancy, depending on local laws and the views of the patient and doctor.

A ‘high risk’ result in the screening tests results in considerable anxiety for the mother and also her close supports. These women should be offered appropriate counselling and further testing as soon as possible. A quick result may be available after 24 hours through the technique of fluorescence in situ hybridisation (FISH).

The first-trimester combined screen consists of nuchal translucency in combination with maternal age and serum markers, pregnancy-associated plasma protein A (PAPP-A) and the free beta subunit of human chorionic gonadotrophin (fβhCG). Trisomy 21 detection rates are estimated at about 87% for a false-positive rate of 5%.15,16 This rate depends on the timing of the individual components. The test is most informative when the serum markers are performed during the ninth week of gestation and the nuchal translucency component during the twelfth week. The advantages of the first-trimester test include higher detection rates, more straightforward termination procedures for those choosing to terminate an aneuploid pregnancy, and earlier reassurance.16

Nuchal translucency can be used alone. This approach is often taken for multiple gestations.

Second-trimester maternal serum screening using a combination of markers that include alpha-fetoprotein (AFP), human chorionic gonadotrophin (hCG), unconjugated oestriol (uE3) and inhibin A. Detection rates for trisomy 21 are usually quoted as 80% for a false-positive rate of 5%. Screening can be undertaken between 15 and 20 weeks’ gestation.

A number of ‘soft’ markers have been described which increase the risk of aneuploidy when present. These include nasal bone hypoplasia, cystic hygroma, abnormal ductus venosus flow and tricuspid regurgitation at the first-trimester ultrasound. Markers identified at the routine second-trimester morphology scan include nuchal translucency, short femur or humerus, pyelectasis, echogenic bowel, echogenic intracardiac focus, single vessel cord and any major structural malformation. Definitive testing is usually offered to women with two or more of these markers, which in studies were observed in 15.1% of cases and 1.6% of normal controls.17

It is worth noting that many people have a somewhat misplaced confidence in the ability of the second-trimester morphology scan to detect chromosomal abnormalities. Detection rates based on this ultrasound alone have been quoted at around 30%. The focus of this scan is really directed at the detection of structural abnormalities. Even these detection rates differ, being highest for spinal anomalies and lowest for cleft lip and digit anomalies.

THE STANDARD ANTENATAL CHECK

Smoking

Evidence indicates serious fetal risks associated with maternal smoking. Meta-analysis has demonstrated twice the normal risk of low birth weight for babies of mothers who smoke (RR 2.04). Preterm birth is a third more likely (RR 1.34) and IUGR risk is more than doubled (RR 2.28). The risk of sudden infant death syndrome is almost three times higher (RR 2.76), and maternal smoking is associated with 10% of stillbirths (RR 1.33) and spontaneous abortions (RR 1.36).18,19

Evidence clearly supports the effectiveness of smoking cessation interventions in reducing smoking rates in pregnant women, as well as reducing preterm birth and low birth weight. Women should be asked about their smoking behaviour at every antenatal visit, using multiple-choice or open-ended questions. The response should be documented in the antenatal record. Smoking cessation interventions should be offered to all pregnant women who smoke or who have recently quit. At every visit, women should be advised about the risks to their own and their babies’ health, and the benefits of quitting at every stage should be emphasised. The five-step strategy includes Ask, Advise, Assess, Assist and Ask again at each antenatal visit. The cycle should be repeated throughout pregnancy, due to high relapse rates in quitters, inaccurate reporting by women of their smoking status and the impact of changed circumstances on women’s motivation.

The evidence regarding the relative risks and benefits of nicotine replacement therapy or other pharmacotherapies is currently insufficient. A cognitive-behavioural approach remains the approved intervention.

Blood pressure measurement

Blood pressure should be recorded at every antenatal visit. Measurements should be taken after 2–3 minutes of the woman sitting, with her feet supported. A standard-size cuff should be used for women with an arm circumference less than 33 cm and a large cuff for an arm circumference greater than this. Diastolic blood pressure readings should be recorded using the Korotkoff V sound (disappearance). If Korotkoff V is not present, then phase IV should be recorded.

Hypertension is defined as systolic blood pressure of 140 mmHg and/or diastolic blood pressure of 90 mmHg. Previous definitions included an incremental rise of 30 mmHg systolic or 15 mmHg diastolic compared to blood pressure as measured in the first trimester; however, most recent definitions have excluded the incremental rise in favour of the former definition. Automated devices should not be used and the role of ambulatory monitoring is currently uncertain. Elevated blood pressure is one of the early signs of preeclampsia, a major cause of maternal and perinatal morbidity (see Fig 54.1). Early detection is important, as the condition can progress rapidly. Hypertension in pregnancy without preeclampsia is also associated with adverse perinatal outcomes. A diagnosis of hypertension in pregnancy requires early assessment by a specialist obstetrician. A clinical diagnosis of preeclampsia is usually made when hypertension occurs with one or more of proteinuria, renal insufficiency, biochemical liver abnormalities, neurological signs, haematological disturbances or fetal growth restriction, and again it requires early assessment by a specialist obstetrician.

image

FIGURE 54.1 The clinical effects of preeclampsia

Blood pressure greater than 170/110 mmHg requires immediate admission to hospital.

Measurement of the symphyseal–fundal height

The symphyseal–fundal height is an indirect measure of fetal growth. If the measurement is larger or smaller than expected, an ultrasound assessment may be required. Possible causes include macrosomia, intrauterine growth restriction (IUGR), polyhydramnios, oligohydramnios, malpresentation and uterine anomalies.

Accurate dates are essential for correct diagnosis. Evidence supports either palpation for fetal size or measurement of the symphyseal–fundal height; however, the latter may provide a greater degree of reliability and consistency when the woman has multiple carers. Measurement of the fundus should start at the variable point (the fundus) to the fixed point (the symphysis pubis) using a non-elastic tape measure. The centimetre markers should be face down during the measurement, to discourage bias on the part of the examiner. Measurements should be recorded in a consistent manner. This clinical assessment of fetal growth is not useful in maternal obesity. Women with BMI over 35 should have a third-trimester ultrasound assessment of fetal growth and wellbeing to detect IUGR, which may otherwise remain undiagnosed.

Intrauterine growth follows a standard curve pattern. The maximum rate of growth occurs between 20 and 32 weeks and is generally 1 cm per week. After 32 weeks’ gestation, the rate of growth decreases slightly. Any variation in measurement from the expected may lead to a diagnosis of small for gestational age (SGA) or large for gestational age (LGA). These are somewhat vague terms that relate to the 10th and 90th centiles respectively and may or may not represent pathology. A baby who is SGA may be well and constitutionally small or may have IUGR. The diagnosis of IUGR is very important as these fetuses are at high risk of fetal death in utero, especially in postdates pregnancies. Other risks for these fetuses include perinatal morbidity, neurodevelopmental delay and endocrinological disorders. IUGR is usually further subdivided into symmetrical and asymmetrical, based on measurements of head size compared to body measurements such as abdominal circumference and femur length. Symmetrically small fetuses are more likely to have chromosomal abnormalities or intrauterine infection, as opposed to asymmetric growth restriction, which is more likely to be due to placental insufficiency and reflects the phenomenon of head sparing, by which the fetus attempts to preserve the blood supply to its most important organ, the brain, at the expense of the rest of the body. The diagnosis of IUGR really rests on evidence of slower growth than expected from two scans more than 2 weeks apart, but the diagnosis of placental insufficiency can be inferred at a single examination on the basis of a small baby and the abnormalities of markers of biophysical wellbeing. These include the amniotic fluid index (AFI), Doppler flow studies of the umbilical artery, middle cerebral artery and ductus venosus. Changes in the latter two suggest that the changes in blood flow associated with head sparing are taking place.

image

FIGURE 54.2 Normal presentation: A Engagement and flexion of the head; B Internal rotation; C Delivery by extension of the head after dilatation of the cervix; D Retraction of the uterus leading to delivery of the placenta

image

FIGURE 54.3 Breech presentation: A frank, B complete; C incomplete

Any baby labelled as SGA clinically should receive some kind of ultrasound assessment of growth and wellbeing, depending on the gestation. From 36 weeks’ gestation it may be more difficult to obtain an accurate estimation of fetal size due to technical problems such as head engagement, and the full growth assessment may be replaced by a modified biophysical profile consisting of AFI, Doppler studies and cardiotography. If all these tests are within normal range it suggests that the fetus is well and unlikely to be at risk. These tests should be performed weekly for continued reassurance. Most maternity centres offer these services in day assessment format.

The diagnosis of LGA suggests a possible diagnosis of macrosomia. Macrosomia is associated with uncontrolled diabetes and poor outcomes such as increased risk of shoulder dystocia. A diagnosis of macrosomia may alter management decisions during labour—for example, in the setting of vaginal birth after caesarean. Again, ultrasound assessment should be undertaken.

Fetal presentation and descent

A check to determine the presenting part should be performed as part of fetal palpation from about 30 weeks. Malpresentation is more likely with increasing maternal age, probably secondary to increasing incidence of uterine factors such as fibroids, which may alter the shape of the cavity and thus predispose to breech presentation or the uterine laxity associated with multiparity. The Term Breech Trial demonstrated a decrease in perinatal mortality or serious morbidity in developed countries for delivery by planned caesarean section rather than planned vaginal birth with no increase in serious morbidity or mortality for mothers.20 Following the findings of this trial, practice in general has changed to favour elective caesarean section for all breech presentations at term, both multigravid and primigravid. This has increased the importance of the diagnosis of breech presentation, to allow for appropriate counselling.

The consequence of the Term Breech Trial has been a small but notable increase in the caesarean section rate. The only intervention proved to reduce this increase is external cephalic version (ECV). This has been found to be a safe and well-tolerated procedure which should be offered to women with a breech or transverse presentation in the last few weeks of pregnancy.

A presenting part remaining high at term, and particularly at full term, may be an indicator of cephalopelvic disproportion. If the presenting part is very mobile, there is a small risk of cord prolapse in the event of spontaneous ruptured membranes.

Fetal heart auscultation

Listening to the fetal heart at each visit is of no proven clinical benefit but is widely thought to be of psychological benefit to the mother. It should be offered at least at every visit after 20 weeks’ gestation.

Some practices that are not useful

Recording the maternal weight at every visit has been standard practice for many years, but there is no conclusive evidence that it is a useful screening tool in the detection of IUGR, macrosomia or preeclampsia. Maternal weight and height should be measured at the first visit and the maternal BMI recorded. BMI < 20 is associated with increased complications including preterm labour and nutritional deficiencies, as well as the possibility of eating disorders. BMI > 35 is associated with increased complications including preeclampsia, hypertension, postdates pregnancy and operative delivery for dystocia.

Routine weighing at each visit should be confined to circumstances where it is relevant.

Routine screening for proteinuria in low-risk women after the first visit is also no longer recommended. Evidence suggests high rates of both false-positive and false-negative samples compared to the gold standard, the 24-hour urine collection. If the woman is noted to be hypertensive, a dipstick urinalysis for proteinuria is still recommended, although most will require 24-hour urine collection for proper assessment of proteinuria. Regular dipstick urinalysis may still be of value in high-risk patients.

RESOURCES

3 centres collaboration, guidelines on antenatal care. http://www.3centres.com.au/guide_frame.htm.

Food Standards Australia New Zealand, Advice for women with babies on their minds or in their arms. http://www.foodstandards.gov.au/consumerinformation/adviceforpregnantwomen/.

Health Insite, Exercise and pregnancy. http://www.healthinsite.gov.au/topics/Exercise_and_Pregnancy.

REFERENCES

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5 Poobalan AS, Aucott LS, Gurung T, et al. Obesity as an independent risk factor for elective and emergency caesarean delivery in nulliparous women—systematic review and meta-analysis of cohort studies. Obes Rev. 2009;10(1):28-35.

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7 3 Centres Collaboration. Guidelines on antenatal care (last reviewed 2006). Mercy Hospital for Women, Southern Health and Royal Women’s Hospital, Melbourne. Online. Available: http://www.3centres.com.au/guide_frame.htm.

8 Khan-Neelofur D, Gülmezoglu M, Villar J. Who should provide routine antenatal care for low-risk women, and how often? A systematic review of randomised controlled trials. WHO Antenatal Care Trial Research Group. Paediatr Perinat Epidemiol. 1998;12(Suppl 2):7-26.

9 Villar J, Carroli G, Khan-Neelofur D, et al. Patterns of routine antenatal care for low-risk pregnancy. Cochrane Database Syst Rev. 2001;4:CD000934.

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13 Mater Hospital Perinatal Epidemiology Unit and Queensland Council on Obstetric and Paediatric Morbidity and Mortality. Evidence-based clinical practice guidelines for the prevention of neonatal early-onset group B streptococcus disease. MPEU and QCOPMM, Brisbane; 2000 (cited in 3 centres collaboration – see ref 7).

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15 Jaques AM, Halliday JL, Francis I, et al. Follow-up and evaluation of the Victorian first-trimester combined screening programme for Down syndrome and trisomy 18. BJOG. 2007;114(7):812-818.

16 Breathnach FM, Malone FD. Screening for aneuploidy in first and second trimesters: is there an optimal paradigm? Curr Opin Obstet Gynecol. 2007;19(2):176-182.

17 Bethune M. Literature review and suggested protocol for managing ultrasound soft markers for Down syndrome: thickened nuchal fold, echogenic bowel, shortened femur, shortened humerus, pyelectasis and absent or hypoplastic nasal bone. Australas Radiol. 2007;51(3):218-225.

18 Lumley J, Oliver S, Waters E. Interventions for promoting smoking cessation during pregnancy. Cochrane Database Syst Rev. 2000;2:CD001055.

19 English D, Holman CDJ, Milne Winter MG, et al. The quantification of drug-caused morbidity and mortality in Australia 1995: Part 2. Canberra: Commonwealth Department of Human Services and Health, 1995.

20 Hannah ME, Hannah WJ, Hewson SA, et al. Planned caesarean section versus planned vaginal birth for breech presentation at term: a randomised multicentre trial. Term Breech Trial Collaborative Group. Lancet. 2000;356(9239):1375-1383.

Acknowledgment

The reference for most of the information provided in this chapter is: 3 Centres Consensus Guidelines on Antenatal Care, Mercy Hospital for Women, Southern Health and Royal Women’s Hospital, Melbourne, 2006.

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