Effect of breast-feeding status on prolactin secretion and resumption of menstruation.

This study investigated prospectively the effect of supplementary breast feeding on the duration of lactational amenorrhoea and serum prolactin levels during prolonged breast feeding in a group of 34 Australian mothers. Although supplementary feeding correlated statistically with the decline in mean serum prolactin levels and the subsequent resumption of menstruation, critical analysis of the data revealed that serum prolactin levels were declining with time before the introduction of supplementary feeding. It was concluded that the resumption of menstruation during prolonged lactational amenorrhoea is associated with the introduction of supplementary infant feeding, but other factors may be more important in this process. The good correlation between the decline in serum prolactin levels and the return of cyclic ovarian activity in individual mothers suggests that measurement of serum prolactin level may be a useful predictive index for returning fertility during breast feeding.