Synthetic progesterone. Used for the treatment of endometriosis.In association with estrogen it has been used as a birth-control medication (e.g. Estradiol + Dienogest) A latest update no published data on excretion into breast milk were found. Progesterone and other related progestin drugs are excreted into breast milk in clinically non-significant amount, and, no problems have been observed in infants whose mothers were treated with this medication. Plasma levels of these infants were usually very low. It has been occasionally observed an increase of prolactin with increased milk production, however, it would be advisable to start taking it until breastfeeding is well established (first 4 to 6 weeks postpartum).