COMPARISON OF EFFECTS OF BREAST-FEEDING PRACTICES ON BIRTH-SPACING IN3 SOCIETIES - NOMADIC TURKANA, GAINJ, AND QUECHUA

Variation in the duration and pattern of breast-feeding contributes si gnificantly to inter-population differences in fertility. In this pape r, measures of suckling frequency and intensity are used to compare th e effects of breast-feeding practices on the duration of lactational a menorrhoea, and on the length of the birth interval in three prospecti ve studies undertaken during the 1980s, among Quechua Indians of Peru, Turkana nomads of Kenya, and Gainj of Papua New Guinea. In all three societies, lactation is prolonged well into the second year postpartum , and frequent, on-demand breast-feeding is the norm. However, the dur ation of lactational amenorrhoea and the length of birth intervals var y considerably. Breast-feeding patterns among Gainj and Turkana are si milar, but Turkana women resume menses some 3 months earlier than do t he Gainj. The average birth interval among the Gainj exceeds that of n omadic Turkana by over 15 months. Suckling activity decreases signific antly with increasing age of nurslings among both Gainj and Quechua, b ut not among Turkana. Earlier resumption of menses among Turkana women may be linked to the unpredictable demands of the pastoral system, wh ich increase day-to-day variation in the number of periods of on-deman d breast-feeding, although not in suckling patterns. This effect is in dependent of the age of infants. The short birth intervals of Turkana women, relative to those of the Gainj, may be related to early supplem entation of Turkana nurslings with butterfat and animals' milk, which reduces energetic demands on lactating women at risk of negative energ y balance.