The purpose of this study is to test whether misoprostol is as effective as oxytocin for treating primary postpartum hemorrhage (PPH) with uterine atony as the suspected cause in two circumstances: 1) where women have received prophylactic uterotonics in the third stage of labor; and 2) where no prophylactic uterotonics have been given in the third stage of labor.

Postpartum hemorrhage (PPH) remains a major cause of maternal deaths worldwide. Misoprostol offers several advantages over oxytocin and ergometrine, the drugs currently used to treat PPH. For example, misoprostol is stable at high temperatures and has a shelf life of several years, it is easy to administer, it can be given to hypertensive patients, and it is inexpensive. This randomized, double-blind placebo-controlled trial will test whether misoprostol is as effective as oxytocin in treating primary PPH in hospital births, both when women have received prophylactic uterotonics in the third stage of labor and when they have not. Blood loss will be measured for all consenting women who deliver vaginally. If PPH occurs and uterine atony is the suspected cause, women will be randomized to receive either: a) four 200 µg pills of misoprostol sublingually and an IV of saline (resembling oxytocin) or b) four placebo tablets resembling misoprostol sublingually and 40 IU oxytocin by IV. This study seeks to answer the following questions: * Is misoprostol as effective as oxytocin for treatment of primary PPH for women who do and do not receive oxytocin prophylaxis in the third stage of labor? * Does misoprostol have an acceptable safety profile when given as an 800 µg sublingual dose to treat PPH? * Is the side effect profile of misoprostol acceptable to women? This study will take place in hospitals located in Burkina Faso, Ecuador, Egypt, Turkey, and Vietnam.