Fibrinolytic activity of uterine fluid in oral contraceptive users

The fibrinolytic activity of uterine fluid increased gradually during the menstrual cycle in oral contraceptive (OC) users. This is in contrast to the low activity found during the luteal phase in non-users. It is concluded that the “synthetic gestagens” contained in the OCs used in this study influence the fibrinolytic activity of uterine fluid in a different way than does native progesterone during the normal luteal phase. This may imply an additional contraceptive effect of OCs.