What is the natural family planning method of contraception?

Updated: Dec 10, 2018
  • Author: Frances E Casey, MD, MPH; Chief Editor: Richard Scott Lucidi, MD, FACOG  more...
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Answer

Answer

Natural family planning is one of the most widely used methods of fertility regulation, particularly for those whose religious or cultural beliefs do not permit devices or drugs for contraception. This method involves periodic abstinence, with couples attempting to avoid intercourse during a woman's fertile period, which is around the time of ovulation. Techniques to determine the fertile period include the calendar method, cervical mucus method, or the symptothermal method.

The calendar method is based on 3 assumptions as follows: (1) A human ovum is capable of fertilization only for approximately 24 hours after ovulation, (2) spermatozoa can retain their fertilizing ability for only 48 hours after coitus, and (3) ovulation usually occurs 12-16 days before the onset of the subsequent menses. The menses is recorded for 6 cycles to approximate the fertile period. The earliest day of the fertile period is determined by the number of days in the shortest menstrual cycle subtracted by 18. The latest day of the fertile period is calculated by the number of days in the longest cycle subtracted by 11.

With the cervical mucus method, the woman attempts to predict her fertile period by quantifying the cervical mucus with her fingers. Under the influence of estrogen, the mucus increases in quantity and becomes progressively more elastic and copious until a peak day is reached. This is followed by scant and dry mucus, secondary to the influence of progesterone, which remains until the onset of the next menses. Intercourse is allowed 4 days after the maximal cervical mucus until menstruation.

The symptothermal method predicts the first day of abstinence by using either the calendar method or the first day mucus is detected, whichever is noted first. The end of the fertile period is predicted by measuring basal body temperature. The basal body temperature of a woman is relatively low during the follicular phase and rises in the luteal phase of the menstrual cycle in response to the thermogenic effect of progesterone. The rise in temperature can vary from 0.2-0.5°C. The elevated temperatures begin 1-2 days after ovulation and correspond to the rising level of progesterone. Intercourse can resume 3 days after the temperature rise.


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