Association Between First-Trimester Subchorionic Hematomas and Adverse Pregnancy Outcomes After 20 Weeks of Gestation in Singleton Pregnancies

OBJECTIVE:To assess the association of first-trimester subchorionic hematomas with pregnancy outcomes after 20 weeks of gestation in women with singleton pregnancies. METHODS:We conducted a retrospective cohort study of all women with singleton pregnancies presenting for prenatal care before 14 weeks of gestation over a 3-year period at a single obstetric practice. All patients underwent routine first-trimester ultrasound examinations. We compared rates of adverse pregnancy outcomes at more than 20 weeks of gestation in women with and without a subchorionic hematoma on the initial ultrasound examination, excluding women with pregnancy loss before 20 weeks of gestation. RESULTS:From January 2015 to December 2017, a total of 2,172 women met the inclusion criteria for the study, 389 (17.9%) of whom had a subchorionic hematoma (mean largest diameter 2.1±1.4 cm). Women with subchorionic hematomas had their first ultrasound examination at earlier gestational ages (8 5/7 vs 9 6/7 weeks, P