Breast-feeding and fertility: sociocultural factors.

Several epidemiological and laboratory investigations have confirmed the traditional beliefs that lactation prolongs postpartum amenorrhea and provides some degree of protection against pregnancy even after the resumption of menstruation [ 12,2 11. The two crucial factors that determine the duration of this infertile period are the duration of unsupplemented lactation and the total duration of lactation [ 12,161. The results of some studies have suggested that the effects of age, parity, sociocultural factors (including socioeconomic variables; education and employment status) on fertility during lactation are mainly attributable to variations in breastfeeding practices [ 12,2 11. Studies undertaken during the last decade have suggested that, in addition to breast-feeding practices [ 13,15, 171, several other factors such as maternal nutritional status [9,10,19], infant nutrition, morbidity and mortality under the existing conditions of health and nutritional care [8,12,22] may each have a role in determining the return of fertility. Available information suggests that prolactin plays a crucial role in many, if not in all, the physiological responses during lactation. Prolactin is thought to be the major factor in the initiation of lactation and in the maintenance of relative infertility during lactation [ 131. However, the role of prolactin in the maintenance of