The lactational histories of 500 Sudanese women were studied retrospectively to examine postpartum lactational amenorrhoea as a method of family planning. Particular attention was given to the factors affecting postpartum lactational amenorrhoea, including supplementary feeding and the use of modern contraceptive methods. Breast-feeding was overwhelmingly practised (90%) among this sample, which was roughly representative of the Sudanese population as a whole. The prevalence of amenorrhoea among this group of lactating women was quite high (73%). Duration of lactational amenorrhoea ranged from 2 to 36 months with a median of 12 months.
Introduction of supplementary feeding had little effect on lactational amenorrhoea up to the 9th month of breast-feeding. Beyond the 12th month of breast-feeding, lactational amenorrhoea was significantly prolonged by postponing the introduction of supplementary feeding until the 4th month or later.
Ovulation, and hence conception, during lactational amenorrhoea was unpredictable. It occurred as early as the 3rd or as late as the 36th month postpartum. Conceptions interrupting lactational amenorrhoea soon after delivery (3–9 months) were more frequent among primiparous women. The failure rate of lactational amenorrhoea as a contraceptive was 8·4%. Though extremely high compared to that of the pill, lactational amenorrhoea was more useful as a fertility control mechanism because, in this study, a high proportion of women initiated pill use, but soon discontinued it because of side effects. Modern contraceptive practice was not prevalent. Amenorrhoeic mothers accepted the pill after the 6th month postpartum (41%), compared to lactating mothers whose menses had returned who started it much earlier. Forty-nine percent of the women studied relied completely on the protection of lactational amenorrhoea. Fifty-seven percent of all lactating women who used the combined pill reported a reduction in milk production. There are several policy implications of this study.