Contraception: Physiological Methods

WITHDRAWAL OR COITUS INTERRUPTUS

There is no doubt that withdrawal - also known as coitus interruptus or the pull-out method - is the best known and most widespread method in this group. It is also the oldest, since it is mentioned in the Bible. It is important to know that the withdrawal must not only be completely beyond the genital organs but also outside the vulva, since some pregnancies can occur following vulval coitus. In addition, if a second coitus takes place fairly rapidly, there may be a sufficient number of spermatozoa remaining in the urethra to cause pregnancy. Coitus interruptus has many advantages because no artificial means are needed; it is practical and readily available. On the other hand, a major drawback is the fact that some men have difficulty in gauging the imminence of ejaculation and withdraw just a tiny bit too late, which seems to be the greatest cause of failure.

THE OGINO-KNAUSS METHOD

The Ogino-Knauss or rhythm method consists in identifying the moment of ovulation after observing the menstrual cycle for at least six months. It is known that ovulation occurs in most women fourteen days before the next menstruation. If a woman is very regular (menstruates every 28 days), ovulation will occur on day 14, which makes the method fairly simple, because abstinence from day 9 to day 19 could prevent the majority of pregnancies. Unfortunately, many completely normal women are nonetheless irregular, which makes using this method more difficult. In addition, both partners must agree on avoiding unprotected relations during fertile periods, or else use one of the barrier methods described further on.

SYMPTO-THERMAL METHOD

This method is based on three signs of fertility. The cervical mucus becomes clearer and more elastic as ovulation approaches. The position of the cervix, at the base of the vagina, as well as its texture and the size of its opening change depending on the point in the cycle, but this is difficult to evaluate in most cases. The cervix reaches its highest position at ovulation. And, finally, the production of progesterone acts on the thermoregulators making the woman's temperature rise by half a degree centigrade following ovulation. If this method is to be really effective, unprotected sexual activity should not take place until the higher temperature or elastic mucus have been present for 3 days. It is then clear that ovulation has occurred once again. In the case of women with irregular cycles, the period of abstinence must be fairly long after ovulation, which is why many of them use this method combined with the rhythm method.

BILLINGS METHOD

The Billings method is based on observation of changes in cervical mucus during the normal menstrual cycle. Under the effect of estrogen, the cervix secretes a thready substance, which is as transparent as water and feels like raw egg white. Under the effect of progesterone - and therefore after ovulation once again - the mucus becomes viscous and thick, almost forming a plug blocking the penetration of spermatozoa. This method requires a great deal of motivation on the part of the couple.

The contraceptive effect of all these physiological methods is difficult to determine because of the methodological problems involved in studying them. According to the World Health Organization, the failure rate ranges from 1%-20%, depending on the care taken in practising them.

OVULATION PREDICTOR KIT

These test kits are available in pharmacies and are used to detect a particular level of luteinizing hormone (LH) in the urine or saliva and so predict the moment of ovulation, which generally occurs that day or the next. The main purpose of these tests is to help women conceive, not to prevent conception. In Europe, however, this type of kit is being marketed for contraceptive purposes but studies have shown that its failure rate is 6% or more.

LACTATIONAL AMENORRHEA METHOD

This method can be 98% effective if certain rules for breast-feeding are followed. The mother must not have started menstruating again during the breast-feeding period. The baby must be breast-fed exclusively (i.e. receive no formula) and the time between feedings must not be longer than every 4 hours during the day and every 6 hours at night. In addition, the baby must be less than 6 months old.