Maternal Stressors and Social Support in Early Pregnancy and the Risk of Stillbirth Among Fetuses With Birth Defects: Exploring Effect Modification by Race/Ethnicity

BACKGROUND: Prenatal stress and social support are associated with adverse birth outcomes, including stillbirth, in the general population. Their relationship to stillbirth among fetuses with birth defects is unclear. Using data from the National Birth Defects Prevention Study and the Birth Defects Study To Evaluate Pregnancy exposureS, we examined associations between maternal stress and social support and the risk of stillbirth among fetuses with birth defects and whether these associations differed by maternal race/ethnicity. METHODS: Participants self-reported exposure to stressors and social supports experienced 3 months before conception through the first trimester. Using log-binomial models, we estimated relative risks (RR) and 95% confidence intervals (CI) of stillbirth associated with high stress and low social support, adjusting for maternal age and race/ethnicity. We assessed additive and multiplicative effect measure modification by maternal race/ethnicity. RESULTS: Neither stress nor social support was associated with stillbirth among fetuses with birth defects. Although we did not observe interaction, we observed increased risk of stillbirth among non-Hispanic Black women with low stress (RR = 2.1, 95% CI = 1.3-3.6), Hispanic women with low stress (1.4, 1.0-2.1), and non-Hispanic Black women with high stress (2.8, 1.4-5.2) compared to non-Hispanic White women with low stress. We observed a similar pattern of results for low social support. CONCLUSIONS: Stress and social support were not associated with stillbirth in fetuses with birth defects. We observed elevated risk of stillbirth among non-Hispanic Black women regardless of stress and social support levels.