Factors associated with second-trimester pregnancy loss in women with normal uterine anatomy undergoing in vitro fertilization.

Abstract

To evaluate factors associated with second-trimester pregnancy loss in patients with normal uterine anatomy who conceived through in vitro fertilization. Women aged 21-44 years with ongoing in vitro fertilization pregnancy (at least one fetus with fetal heart tones at 12 weeks of gestation) at an academic hospital from 2001 to 2012 were eligible for inclusion in this retrospective cohort. Comprehensive uterine evaluation permitted inclusion of only women with anatomically normal uterine cavities. Maternal and clinical characteristics associated with spontaneous second-trimester pregnancy loss (between 12 1/7 and 23 6/7 weeks of gestation) were assessed. Multivariable logistic regression generated adjusted odds ratios (ORs), 95% confidence intervals (CIs), and Wald two-sided P values. Among ongoing second-trimester pregnancies, 60 (2.1%) ended in spontaneous pregnancy loss and 2,841 (97.9%) ended in live birth. Multiple gestations (twins or more) conferred greater odds of pregnancy loss (adjusted OR 1.93, CI 1.15-3.24, P=.01) and were more prevalent among losses (48.3%) than live births (34.1%). Uterine leiomyomas were present in 16.7% of losses and 4.7% of live births and were associated with a nearly fourfold increased odds of second-trimester pregnancy loss (adjusted OR 3.82, CI 1.85-7.89, P<.001). Women with obese body mass index ([BMI] 30 or higher) at cycle start experienced twofold greater odds of pregnancy loss compared with normal-weight women (adjusted OR 2.38, CI 1.05-5.65, P=.04). There were eight obese women (32%) among losses and 209 obese women (16.5%) among live births. In vitro fertilization treatment parameters were not associated with odds of second-trimester loss nor were maternal age, ethnicity, or history of recurrent pregnancy loss. Odds of second-trimester spontaneous pregnancy loss among in vitro fertilization conceived pregnancies were greater with multiple gestations, leiomyomas, and obese maternal BMI. II.