Natural Family Planning
From Encyclopedia of Sex and Sexuality
Birth control based on abstinence during the time that the woman is supposed to be fertile is commonly known as “natural family planning.” There are several ways in which to decide when this time frame is, but none of them is perfectly exact, which is why this type of planning has a failure rate of 20 percent as typically used, meaning that, in the course of a year, 20 women out of 100 will become pregnant using this method of birth control. (Rates are much lower for perfect use, including 9 for the calendar method alone and 3 for the symptothermal method described below.) On the other hand, these same methods can also be used to help plan a pregnancy in cases in which a woman is having difficulty conceiving or in instances when the timing of the arrival of a baby is important.
The first of these is the calendar, or “rhythm,” method. The woman must keep track of when she has her periods over a number of months in order to see how regular her periods are. While textbooks may say that a woman ovulates fourteen days after her period ends, there are no absolute rules. Some women are quite regular while others vary greatly. In order to be “safe,” a woman must find out what her longest cycle is and what her shortest cycle is, and then work out the mathematics, taking account of the fact that sperm may live some days within her reproductive system, as can the egg (which can survive for twenty-four hours or more), so that there must be a minimal eight-day safety margin. For most couples, what this means is that they must not engage in any unprotected sexual intercourse for about ten days during the middle of the woman’s cycle.
Another way of calculating the safe time is to use the basal body temperature method. The basal body temperature is the body’s temperature first thing in the morning before rising. If a woman is ovulating, her basal body temperature will be between 0.4 to 0.8 degrees higher than her normal body temperature. To calculate effectively the woman must keep a record of her morning temperatures so that she can make a comparison, and she must also use this method in conjunction with the calendar method in order to have an idea of when to expect ovulation, because any sperm already on their way toward the egg could impregnate her. There may also be other factors that can raise a woman’s temperature, such as an infection from a cold, so that she must remain in tune with her body’s overall health when using this method.
With the cervical mucus method the woman observes the changes in her cervical mucus. Normally the mucus is cloudy and tacky, but a few days before ovulation it will become clear and slippery, stretching between the fingers like raw egg whites, and there will be more of it. When this happens the woman must refrain from intercourse, or use a barrier method. Of the three, this is the least effective method, with pregnancy rates having been shown to be as high as 40 in 100 per year.
A combination of these three methods, called the symptothermal method, is, of course, more effective than any single natural family planning method alone. The last method, called the postovulation method, requires that the woman either abstain from intercourse or use a barrier method from the beginning of her period until the morning of the fourth day after her predicted ovulation, more than half of her menstrual cycle.
Natural family planning methods are safe, do not have any side effects, do not cost very much to implement and are accepted by most religious groups. The more a woman studies how to use natural family planning, the more skilled she will become in using them. Taking a course is highly recommended for anyone thinking of using these methods. However, natural family planning is far from foolproof even if practiced perfectly. There are other factors that can seriously reduce the effectiveness of this method of birth control, such as infections, lack of sleep, or jet lag, which interfere with the basal body temperature, or vaginal secretions which alter the cervical mucus. Finally, natural family planning offers no protection against sexually transmitted diseases.