Release of prolactin during pregnancy: effect of sulpiride.

The aim of this trial was to study the prolactin-releasing capacity of the pituitary during pregnancy by means of an acute stimulation with sulpiride. Thirty women with normal pregnancies were included in the study (first trimester, nine women; second trimester, eleven women thir trimester, ten women). Each woman received an intramusclar injection of 100 mg of sulpiride sulfate between 8 and 9 A.M. Three similar groups received injections of a saline solution. Blood samples were obtained before and 30 and 60 minutes after the injection. In each sample the prolactin concentration was determined by radioimmunoassay. Basal prolactin levels increased during pregnancy. Significant responses to sulpiride were observed during the three stages of pregnancy, and the levels in the second and third trimesters were higher than those in the firsttrimester. The prolactin-releasing capacity of the pituitary, as judged by the response to sulpiride, seems to be maintained during pregnancy.