Natural methods play an important part in the overall control of world fertility. Lactational amenorrhoea makes a very large contribution to fertility control in developing countries and recent advances in our understanding of the biology of lactation and fertility have enabled guidelines to be prepared to help nursing mothers who wish to use the natural contraceptive effect of breastfeeding to space their families. Methods to identify more reliably the fertile phase of the menstrual cycle, possibly using home monitoring of hormone levels in the urine, would greatly increase the applicability of NFP methods. If used effectively, natural family planning can have a high effectiveness rate but all methods are extremely unforgiving of risk-taking in the fertile phase. More research is required to identify those factors which could serve to improve the efficacy of NFP methods.
PIP: Lactational amenorrhea by means of the natural contraceptive effect of breastfeeding is a valuable tool to space families and control fertility in developing countries. In most developed countries, postpartum women are advised to initiate artificial contraception at about 4 weeks postpartum to prevent conception. However, this approach to postpartum contraception is not appropriate in many countries. Although breastfeeding does inhibit fertility, particularly during lactational amenorrhea, it is still unreliable for family planning. Data from prospective studies showed that the cumulative probabilities of ovulation during lactational amenorrhea were 30.9% and 67.3% at 6 and 12 months, respectively. When ovulatory cycles associated with adequate luteal phases were considered, the corresponding figures were 13.8% at 6 months and 37.5% at 12 months. On the basis of data from 13 studies in 8 countries, the Bellagio consensus statement concluded that breast-feeding provides more than 98% protection from pregnancy during the first 6 months postpartum if the mother is fully breastfeeding. It has been suggested that lactational amenorrhea alone would be a more practical strategy for lactating women in many countries, providing acceptably low cumulative pregnancy rates of about 3 and 6/100 women at 6 and 12 months, respectively. In the 5-center study of the ovulation method of natural family planning carried out by WHO, 94% of the women were able to carry out the method correctly, which yielded a pregnancy rate of 3/100 women-years. In a study, the home ovarian hormone monitor has been used by 37 women over a total of 55 woman-years for pregnancy avoidance. The ovarian hormone monitor gave 5 or more days' warning of ovulation in 99% of cycles and allowed intercourse to be resumed 1-3 days after ovulation in 88% of cycles. The WHO multicenter study of the ovulation method has shown that if the method is used correctly there is a first year probability of failure of 3.4%.