Serum prolactin and suckling

Serum prolactin concentrations basally and in response to suckling as a function of time after delivery. Within the first week after delivery, the basal value is high relative to the nonpregnant state, and there may be a further increase in response to suckling. Several weeks after delivery, the basal value is close to that of the nonpregnant state, but there is still a pronounced increase in response to suckling. Three months after delivery, the basal value is similar to that of the nonpregnant state, and there is a minimal response to suckling, if any.