823 African-American race and subsequent pregnancy outcomes after a prior preterm birth

Abstract

Whether African American (AA) race is a true causal risk factor for recurrent preterm birth (PTB) versus reflective of socioeconomic factors is debated. We investigate if AA race is a risk factor for recurrent PTB and adverse outcomes in the subsequent pregnancy after the first PTB, accounting for select social factors. Retrospective cohort study of nulliparas whose first delivery was between 16-37 weeks gestational age (GA) and had a subsequent pregnancy between 2013-2018. Multiple gestations in the index PTB were excluded. Women were grouped by self-identified race/ethnicity: AA, non-AA. The primary outcome was any recurrent PTB. Secondary outcomes were early PTB <34 weeks, delivery GA, cesarean delivery (CD), and perinatal outcomes. Outcomes were compared between groups; multivariable logistic regression calculated adjusted odds ratios (95% CI) with non-AA women as reference. Of 1744 women with singleton PTBs 16-37 weeks, 257 (15%) had a subsequent delivery in our study period –140 (54%) were AA. AA women were younger, more likely unmarried, used government insurance, and delivered vaginally in the index PTB (all p<0.05). Index PTB GA was similar (30 weeks AA vs 31 non-AA, p=0.12); AA women had a shorter interpregnancy interval (IPI: 11 months [IQR 5-22] vs 15 [9-25], p=0.003). In the subsequent pregnancy, there were no significant differences (crude or adjusted) in PTB <37 weeks, delivery GA, early PTB, preeclampsia, or perinatal outcomes between groups (Table). In fact, there were no subsequent PTBs <28 weeks. Of note, AA women had significantly higher odds of blood transfusion, and lower neonatal birthweights. Outcomes were unchanged when stratifying non-AA women into individual racial/ethnic groups. AA race was not significantly associated with risk for recurrent PTB, even when accounting for select socioeconomic factors – suggesting a role for race perhaps in the index PTB. While AA women had shorter IPIs, IPI was within appropriate ranges. Larger studies of race, recurrent PTB, and availability of immediate long-acting postpartum contraception are needed.