Oxytocin is normally given either rapidly into the vein (bolus) or put into an intravenous bag and administered more slowly, after delivery of the baby by cesarean section. Both of these methods are commonly used. To date there has been little research to demonstrate that one method of giving oxytocin is better than another in women who are more likely to bleed after delivery. The purpose of the study is to see whether a small bolus of oxytocin makes the uterus contract better to reduce bleeding and decreases the need to give additional oxytocin or more powerful drugs in women who are at risk for bleeding after delivery of their baby by cesarean section.