Serum-prolactin in long-lasting lactation amenorrhoea.

Basal serum-prolactin concentrations were high until 15 months post partum in nursing mothers in Central Africa (Lwiro). They were significantly lower in menstruating than in amenorrhoeic nursing mothers. These results support the hypothesis that prolactin is involved in the long-lasting amenorrhoea which occurs in regions where breast-feeding is prolonged for up to 2 years after delivery.