Conception control

Published on 10/03/2015 by admin

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Last modified 10/03/2015

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Chapter 31 Conception control

The availability of safe modern contraceptives has enabled women to avoid unwanted pregnancy, and couples to space their children. Spacing children to intervals of 2 or more years improves a woman’s health.

Contraceptive choices now available permit the woman, or the couple, to choose the most appropriate contraceptive for their particular circumstances. Younger women usually prefer oral contraceptives or expect their male partners to use condoms, whereas older women are more inclined to choose the intrauterine device (IUCD) or a permanent method of birth control, such as tubal ligation or a vasectomy in her partner (Fig. 31.1).

Before choosing a particular contraceptive most people want to know its effectiveness in preventing pregnancy, its safety, and the side-effects associated with its use. A method of evaluating the effectiveness of the various contraceptive methods is the Pearl Index, which calculates the unintended pregnancy rate from the formula:

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The result is expressed as the failure rate per 100 woman years (HWY).

Table 31.1 shows the effectiveness of various contraceptive methods in preventing pregnancy.

Table 31.1 Ranking of contraceptive methods by rate of effectiveness

    Failure Rates per 100 HWY
Group A Most effective  
Tubal ligation/ vasectomyCombined oralContinuous progesterone 0.005–0.04
Combined oral 0.005–0.30
Continuous progesterone 0.07
Group B Highly effective  
IUCD 0.5–3.5
Depot progestogen 1.5–2.3
Diaphragm or comdom
All users 4.0–7.0
Highly motivated 1.5–3.0
Periodic abstinence
All users 10.0–30.0
Highly motivated 2.5–5.0
Group C Less effective  
Coitus interruptus 30.0–40.0
Vaginal foam or cream 30.0–40.0
Group D Least effective  
Postcoital douche 45.0
Prolonged breastfeeding 45.0

Some women find it embarrassing to consult a medical practitioner about contraception and a sensitive doctor will do everything possible to diminish that embarrassment. The ability to listen to and to talk with the woman is of great importance.

The doctor should take a general history, a menstrual history and a sexual history in a non-judgemental way. With this information, the doctor will be better able to help the woman decide which method of contraception she would prefer.

A gynaecological examination should be made, although if the woman is teenaged and has not previously had a vaginal examination it can be deferred to a subsequent visit. If she has not had a Pap smear taken in the previous 2 years, the doctor should suggest that this be done, explaining how the smear is taken and the reason for it.

REVERSIBLE METHODS OF CONTRACEPTION USED BY THE COUPLE

REVERSIBLE METHODS OF CONTRACEPTION USED BY MEN

Condom

Modern condoms, which are made of latex, prelubricated, and supplied in hermetically sealed aluminium sachets, are cheap, efficient and hardly noticeable to either partner. Their advantages are that they can be obtained from a variety of outlets without a doctor’s prescription, and that they offer some protection against sexually transmitted diseases, including the human papilloma virus, chlamydia and the human immunodeficiency virus (HIV). The disadvantage of condoms is that many younger men refuse to use them in the belief that they reduce sexual pleasure and may burst during use.

The pregnancy rate following condom use relates to usage, to the way the condom is put on the penis, and how it is held on after penile detumescence. If consulted by a woman or her partner the doctor should explain how a condom should be used (Fig. 31.3).

REVERSIBLE METHODS OF CONTRACEPTION USED BY WOMEN

Women have more choices of reversible or temporary contraception than men. They may choose:

Barrier methods

Vaginal diaphragm and the cervical cap

The vaginal diaphragm and the cervical cap consist of a thin plastic or latex dome attached to a circular flat, coiled or arching spring rim. The vaginal diaphragm is easier to use than the cervical cap, as it fits diagonally across the vagina. The correct size of the diaphragm is determined by a medical practitioner examining the woman vaginally, by inserting the index and middle fingers as far as they will go into the posterior vaginal fornix and noting how far the index finger reaches behind the symphysis pubis. The diaphragm is made in sizes from 50 mm to 100 mm, in 5 mm steps. After measuring the vagina, the doctor inserts a series of diaphragms or fitting rings until the most appropriate size is found.

Using a diaphragm or a cervical cap requires practice, and after teaching a woman how to use it (Fig. 31.4) many doctors ask the woman to learn the technique at home and return with the diaphragm or cap in place for checking.

When the woman is confident about the technique, she inserts the diaphragm each day or at any convenient time before sexual intercourse is anticipated. It should not be removed for cleaning until at least 6 hours after the last ejaculation. Some women choose to smear a nonoxynol-9 spermicidal cream around the rim, but whether this adds to the effectiveness of the diaphragm in preventing pregnancy is uncertain. It is known to destroy HIV to some extent, which is a benefit.

If a woman chooses a cervical cap she must have a healthy, short cervix. Fitting is carried out by a medical practitioner. The technique of insertion and removal is the same as that for the vaginal diaphragm.