Incidence and risk of stillbirth among various Asian-American subgroups

Short-Term Increases in NO2 and O3 Concentrations during Pregnancy and Stillbirth Risk in the U.S.: A Time-Stratified Case-Crossover Study

Associations between gaseous pollutant exposure and stillbirth have focused on exposures averaged over trimesters or gestation. We investigated the association between short-term increases in nitrogen dioxide (NO2) and ozone (O3) concentrations and stillbirth risk among a national sample of 116 788 Medicaid enrollees from 2000 to 2014. A time-stratified case-crossover design was used to estimate distributed (lag 0-lag 6) and cumulative lag effects, which were adjusted for PM2.5 concentration and temperature. Effect modification by race/ethnicity and proximity to hydraulic fracturing (fracking) wells was assessed. Short-term increases in the NO2 and O3 concentrations were not associated with stillbirth in the overall sample. Among American Indian individuals (n = 1694), a 10 ppb increase in NO2 concentrations was associated with increased stillbirth odds at lag 0 (5.66%, 95%CI: [0.57%, 11.01%], p = 0.03) and lag 1 (4.08%, 95%CI: [0.22%, 8.09%], p = 0.04) but not lag 0-6 (7.12%, 95%CI: [-9.83%, 27.27%], p = 0.43). Among participants living in zip codes within 15 km of active fracking wells (n = 9486), a 10 ppb increase in NO2 concentration was associated with increased stillbirth odds in single-day lags (2.42%, 95%CI: [0.37%, 4.52%], p = 0.02 for lag 0 and 1.83%, 95%CI: [0.25%, 3.43%], p = 0.03 for lag 1) but not the cumulative lag (lag 0-6) (4.62%, 95%CI: [-2.75%, 12.55%], p = 0.22). Odds ratios were close to the null in zip codes distant from fracking wells. Future studies should investigate the role of air pollutants emitted from fracking and potential racial disparities in the relationship between short-term increases in NO2 concentrations and stillbirth.

Hispanic Ethnicity, Nativity and the Risk of Stillbirth

The objective of this study was to examine stillbirth risk by nativity and Hispanic ethnicity. We analyzed births and fetal deaths among women of Hispanic origin within gestational ages of 20-42 weeks from the 2014-2019 Birth and Fetal Death. Foreign-born Hispanic mothers were 8% less likely (HR 0.92, 95% CI 0.90-0.95) to experience stillbirth than their counterparts. Stratified by ethnicity, foreign-born Mexican and Central/South American women had a lower risk of stillbirth (HR 0.85, 95% CI 0.81-0.88 and HR 0.68, 95% CI 0.63-0.75, respectively) while foreign-born Puerto Rican women were more likely to experience stillbirth (HR 1.37, 95% CI 1.24-1.51) than their native-born counterparts. While overall foreign-born Hispanic mothers were less likely to experience stillbirth than native-born Hispanic mothers, this differed depending on ethnicity. Counseling regarding risk of stillbirth among Hispanic women should take into consideration nativity and country of origin as influential factors.