Prevention of Postpartum Hemorrhage With Tranexamic Acid

The study will enroll 45 additional third trimester pregnant women scheduled for nonemergent cesarean sections who are at high risk for hemorrhage. The investigators plan to enroll 30, but to account for lost to follow-up, the investigators will enroll 45. The investigators will also enroll 30 pregnant patients \> 34 weeks of gestation undergoing vaginal delivery, and 30 morbidly obese (BMI \>= 40) pregnant patients undergoing either vaginal or cesarean delivery. However, the investigators will enroll 45 patients in each of these two groups to account for loss to follow up. The investigators will also enroll 45 patients as a control group that will not receive TXA. The total number of enrolled patients will thus be 223. A total of 1 gram of TXA will be administered to patients prior to fetal delivery via three different routes of administration: IV infusion, IV push, and IM injection. The subjects in each group will be divided into three subgroups: Group 1: Up to 15 subjects, TXA dose: 1 gram, Route: IV infusion over 10 minutes Group 2: Up to 15 subjects, TXA dose: 1 gram, Route: IV Push for \<2 minutes Group 3: Up to 15 subjects, TXA dose: 1 gram, Route: IM Injection Plasma sampling: Timing of samples will be relative to the end of drug administration (t = 0) and include: Pre-drug administration, 5-10 minutes, 30-60 minutes, 60-90 minutes, 1.5-3 hours, 3-4 hours, 4-5 hours, 7-8 hours, and 10-18 hours. Each volume of blood draw will be approximately 7-9 mL. Actual times of plasma sampling will be documented. A second IV will be required for participating in the study. Citrated plasma samples will be centrifuged and supernatant will be stored at -70 degree Celsius. Breast milk sampling of no more than 2 mL per time point will occur at time points coinciding with maternal feedings.