Residential Segregation and Fecundability in the Black Women’s Health Study

Residential segregation can influence reproductive outcomes, yet few studies have investigated its effects on fertility. We used data from the Black Women's Health Study, a U.S. prospective cohort study, to estimate the effect of racialized economic segregation on fecundability, the per-cycle probability of conception. Participants enrolled in 1995 and completed biennial follow-up questionnaires. A supplemental module in 2011 asked participants to report, for each birth, whether the pregnancy was planned and the number of months to conceive. Participants also reported any attempts to conceive for ≥ 12 months without success. We operationalized racialized economic segregation using the census tract level Index of Concentration at the Extremes (ICErace + income). We fit proportional probabilities regression models with generalized estimating equations to estimate fecundability ratios (FRs) and 95% CIs, adjusting for age, calendar year, geographic region, early life socioeconomic position, and educational attainment. The analysis included 2857 planned pregnancy attempts from 2183 participants (mean age = 34 years). Relative to participants living in the most privileged group, FRs for participants in the most marginalized, mixed (marginalized) and mixed (privileged) groups were 0.88 (95% CI, 0.74, 1.04), 0.89 (95% CI, 0.78, 1.02), and 0.91 (95% CI, 0.80, 1.04), respectively. Associations were stronger among college-educated and nulliparous participants.