149: Racial disparities in gestational age at delivery among twin pregnancies

Abstract

The PTB rate for non-Hispanic (NH) black women is 60% higher than NH whites; these disparities persist even after controlling for known risk factors. Though disparities in PTB have been well characterized in singleton pregnancies, the relationship in twin pregnancies is understudied. Secondary analysis of a prospective RCT of 17P vs. placebo for PTB prevention in twin gestations. NH blacks and whites were included. Demographic and antenatal characteristics were compared using chi-square, t-test, and fisher’s exact as appropriate. The primary outcome was delivery gestational age, indexed by delivery <28, <34, and <37 weeks gestation. Secondary outcomes included a composite of major neonatal morbidity (death, IVH, BPD, NEC). Kaplan-Meier curves for delivery gestational age were compared by race. Cox proportional hazards models were used to estimate hazard ratios (HR) and 95% CI to adjust the survival analysis for confounders. Backward elimination was performed to select an adjusted model beginning with all maternal and antenatal factors included in Table 1. 540 women with twin gestations met inclusion criteria; 154 (29.5%) were NH black. NH blacks differed from NH whites on several key variables associated with PTB (Table). NH blacks delivered earlier than NH whites (33.6 +/- 4.8 vs. 35.1 +/- 3.5 weeks, p<0.001), and were more likely to deliver <28 weeks (13% vs. 4.9%, p=0.001), <34 weeks (35.1% vs. 24.6%, p=0.014), and <37 weeks (75.3% vs. 66.3%, p=0.041). Differences in delivery GA between NH blacks and whites were consistent across gestation (Figure). In the multivariable Cox model, black race (HR 1.24, 95% CI 1.00-1.52), prior PTB (HR 1.67, 95% CI 1.21-2.30), and presence of a cervical cerclage (HR 3.71, 95% CI 1.83-7.54) were associated with PTB <37 weeks gestation. There were no statistically significant differences between rates of major neonatal morbidity between NH blacks and whites (11.0 vs. 6.7%, p=0.095). NH black women carrying twins have an elevated risk for PTB and deliver earlier compared to NH white women. These findings parallel previously reported PTB disparities in singleton pregnancies.View Large Image Figure ViewerDownload Hi-res image Download (PPT)