Prolactin secretion during prolonged lactational amenorrhoea.

Basal serum prolactin levels were elevated up to 66 weeks postpartum in lactating amenorrhoeic women. The serum prolactin level in fully breast-feeding women was significantly higher than in women who were partially breast-feeding. The mean basal serum prolactin level in menstruating, lactating women was significantly higher than the mean level in women who had weaned and had normal menstrual cycles. The rise in prolactin due to suckling was seen up to 66 weeks postpartum. The marked variability and lack of reproducibility of individual suckling responses may obscure the importance of prolactin secretion in the postpartum period. Nevertheless, this study confirms that prolactin secretion is increased in women with prolonged lactational amenorrhoea.