Human beings have been practisingfor thousands of years. Four thousand years ago, an Egyptian medical text described a prescription for vaginal plugs made of crocodile dung and honey, and the Chinese and Japanese have used thin leather and oiled silk paper condoms for centuries. All methods, whether old or new, are based on one of two principles: either to stop the meeting of sperm and egg, or to discourage a fertilized egg from implanting in the womb. This is achieved by a variety of biological, mechanical, chemical, hormonal and surgical methods.
Biological and natural methods
Biological or ‘safe period’ methods rely on an understanding of the woman’s mentrual cycle. This method is based on identifying the day in the menstrual cycle when ovulation takes place. Taking into consideration that the egg is receptive to sperm for about three days, and that a sperm has a life of up to three days, intercourse on the few days before or after ovulation may result in conception. These are designated as ‘unsafe’ days when sex should be avoided. In a regular 28-daycycle, intercourse must therefore be avoided from the eleventh to the seventeenth day, taking as day one the first day of a menstrual period and ovulation as occurring on day 14.
Safe-period methods offer different ways of calculating when ovulation will occur, so the couple can avoid intercourse during this time. The oldest and most unreliable method of calculation is that which uses the calendar. This requires that the woman keeps a strict record of her cycle for at least six months prior to attempting to use the information. After six months, if her periods are regular, the woman should be able to calculate when ovulation takes place, and so when to avoid intercourse.
A more effective way of calculating is the temperature method. To use this, a woman takes her temperature each morning as soon as she wakes up. The basal body temperature (BBT) will be altered by the hormonal changes of ovulation so that just before an egg is released her temperature will drop. It will then rise at the time of ovulation and remain higher than before by about 0,5°C, until her period begins. Accurate and sensitive monitoring should allow the woman to spot both the drop and rise in her temperature, and so pinpoint ovulation. For obvious reasons this method is only reliable in the second half of the menstrual cycle, after ovulation has occurred. It is not possible to predict ovulation using measurement of temperature for calculating safe days in the first half of the cycle, However, combining this method with other ‘safe period’ methods such as the calender method or the mucus method will enable the woman to draw a more or less reliable conclusion as to the safety of intercourse before ovulation.
The third way of calculating is the mucus method. The mucus produced by the vagina and cervix changes in consistency during a woman’s cycle. Throughout most of the month, it is sticky and forms a plug in the cervix. About four days before ovulation, it becomes more fluid and forms channels which encourage, rather than block, the passage of sperm. This pre-ovulatory mucus can be recognized, being more abundant and less opaque than normal mucus. A drop of mucus at this time, when rubbed between finger and thumb, will be ‘tacky’ and stretch between the digits. At other times in the month it will be drier.
Probably the most successful application of safe-period methods is to combine all three. The couple must be prepared to monitor carefully the woman’s physical state and abstain from intercourse for a substantial period of time each month. Because few women have an absolutely regular menstrual cycle, in practice this means that out of a 28-day-cycle, five or six days are taken up by menstrual bleeding and 12 or 13 by abstention. Intercourse can be enjoyed safely only on 10 or 11 days. Strictly adhered to, safe-period methods have been found to be about 90 per cent effective. This figure however, excludes couples who drop out and become pregnant because they decide to have another baby, or give up the method for other reasons. In many cases because such decisions may have been influenced by the frustations imposed by the method and its difficulties, a higher failure rate is probably more realistic.
Another frustrating, ineffective and extremely ancient method is coitus interruptus. This relies on the man withdrawing his penis from the woman’s vagina just before he comes to orgasm when the sperm are ejaculated. The theory is excellent but the practice has its drawbacks. Before orgasm occurs, the Cowper’s glands at the base of the penis secrete a few drops of lubricating fluid which often contain a few live sperm. This secretion can occur a few minutes before orgasm but after the beginning of intercourse. Thus at the moment of withdrawal, it may already be too late. Withdrawal can also be an immensely frustrating experience for both partners.