Background: Second-trimester pregnancy loss is defined as occurring between 14 weeks, 1 day and 23 weeks, 6 days of gestation, and complicates 1 to 2 percent of diagnosed pregnancies. Possible etiologies include infection, cervical insufficiency, uterine malformations, gene polymorphisms, fetal and placental anomalies, and genetic and acquired thrombophilias. Less is known, however, about associated risks to subsequent pregnancies in women who have experienced a spontaneous second-trimester loss. Edlow and colleagues studied the association between second-trimester pregnancy loss and the risk of a pregnancy loss or preterm birth in a subsequent pregnancy.

The Study: This retrospective cohort study compared subsequent pregnancy outcomes in three groups of women: those with a history of a second-trimester loss; those with a history of preterm birth; and those with a history of a full-term birth. The cohort numbers were powered to detect a sixfold difference in preterm birth. Patients in the pregnancy-loss cohort were identified prospectively through an earlier study, and included women who presented to the Hospital of the University of Pennsylvania. Of the 97 women identified, 30 had subsequent pregnancies that also were delivered at this hospital. Patients in the control cohorts were identified retrospectively through the hospital database and were matched 2:1 to the month of delivery.

Results: The three study groups were demographically similar, except that black women comprised a higher percentage of the pregnancy-loss and preterm birth groups, and women in those groups were less likely to have received prenatal care than women in the full-term birth group. Patients in the second-trimester–loss group had a higher frequency of a subsequent pregnancy loss (27 percent) than those with a previous preterm birth (3 percent) or a history of full-term birth (1 percent). The frequency of preterm birth was also increased to 33 percent in women with a previous pregnancy loss, 39.5 percent in women with a previous preterm birth, and 9.2 percent in women with a previous full-term delivery.

Conclusion: In this small (but adequately powered) study, the authors concluded that spontaneous second-trimester pregnancy loss is significantly associated with poor obstetric outcomes in subsequent pregnancy; patients should be counseled about their potential risks.