[Influence of basal and post-feeding prolactin levels on amenorrhea during breast feeding]. 
Forty five women, with exclusive breastfeeding were studied, (the objective was) to explore the relationship between: basal plasma prolactin (PRL) levels and post-suckling with the duration of postpartum amenorrhea.  Blood samples for measurements of PRL were taken at the third month postpartum, before an episode of suckling and 30 minutes after the suckling was initiated.  The average level of basal PRL was 1,033 +/- 113 mIU/L (mean +/- SE).  Women who presented long periods of amenorrhea, had an increase of the basal PRL in 632 mIU/L (X), compare to those women who had their menses before 180 days postpartum (p = 0.036) women with longer amenorrhea (p = 0.06).  However there were no relationship between the menses at the sixth month postpartum and the increase of post-suckling PRL (delta PRL).  In this study it was found that the levels of basal PRL had correlation with the duration of the amenorrhea, in women with exclusive breastfeeding.