Prediction and Prevention of Preterm Birth (PREVENT-PTB Study)

Inclusion Criteria 1. Subject is greater than or equal to 18 years of age AND 2. Uncomplicated singleton intrauterine pregnancy less than 21 weeks estimated gestation AND 3. No medical contraindications to continuing pregnancy AND 4. No previous classical cesarean section AND 5. No known uterine anomaly AND 6. No history of cervical conization AND 7. No plan for cesarean section prior to 37 0/7 weeks gestation AND 8. No plan for induction of labor prior to 37 0/7 weeks gestation AND 9. Subject has no history of spontaneous preterm delivery AND 10. No prior PPROM less than 34 weeks AND 11. Subject has no signs and/or symptoms of preterm labor AND 12. Subject has intact membranes AND 13. Subject has not received a blood transfusion during the current pregnancy. Exclusion Criteria 1. Subjects who have taken or plan to take progesterone beyond 13 6/7 weeks gestation prior to study enrollment OR 2. Any other medical conditions that put subject at increased risk of preterm birth in the judgment of the site investigator OR 3. The subject has a planned cerclage placement for the current pregnancy OR 4. Previously identified short cervix (less than 2.5 cm by transvaginal ultrasound) prior to enrollment OR 5. Known major structural fetal anomalies that may shorten pregnancy (e.g., anencephaly, holoprosencephaly, schizencephaly, gastroschisis, omphalocele, congenital diaphragmatic hernia) OR 6. Known fetal genetic anomalies that are incompatible with life (e.g., trisomy 13 or trisomy 18) OR 7. The subject has known elevated bilirubin levels (hyperbilirubinemia) OR 8. The subject has taken or plans to take any of the following medications after the first day of the last menstrual period: Enoxaparin, heparin, heparin sodium, low molecular weight heparin, low dose aspirin OR 9. A history of allergic reaction to aspirin or 17-OHPC injections OR 10. Subject does not plan to deliver at an Intermountain Healthcare hospital.