Sangrado del primer trimestre y riesgo de pérdida del embarazo en una cohorte prospectiva

Vaginal bleeding in the first trimester is common, but our understanding of how bleeding relates to the risk of pregnancy loss is limited. In a prospective cohort study, participants provided information on bleeding episodes during early pregnancy and underwent a first-trimester research ultrasonogram. Among 5,425 participants, 25.0% of participants reported first-trimester bleeding, and 12.0% of pregnancies ended in loss. Bleeding was not associated with risk of pregnancy loss (hazard ratio [HR] 0.89, 95% CI, 0.75-1.07). First-trimester bleeding coupled with ultrasound measurements that lagged more than 5 days behind last menstrual period (LMP) dating was associated with increased risk (HR 2.72, 95% CI, 2.10-3.53). These findings indicate that reassurance is appropriate for most patients experiencing first-trimester bleeding when ultrasound measurements align with LMP.