Economic connectedness and fetal and infant death: a population-based cross-sectional study of California

Bridging capital (ie, friendships across socioeconomic strata) increases upward economic mobility, yet its role in shaping health outcomes remains poorly understood. Evidence appears especially limited for low-income communities and populations experiencing disproportionate health risks. We examine the association between economic connectivity, a type of bridging capital, and perinatal health disparities. We used a recently released zip code level measure of bridging capital derived from Facebook data on more than 70 million US adults to examine the associations between social connectedness and fetal and infant death in California (8 million births; 2005 to 2021).

We used generalised estimating equations to test the association between the z-scored economic connectivity and the odds of fetal death and infant death. We used information on median household income in each zip code to focus on mothers residing in the lowest quartile neighbourhoods of income. We also examined non-Hispanic (NH) black mothers in low-income neighbourhoods given that they experience persistently elevated risks of perinatal mortality.

We found strong protective associations (p<0.001) between bridging capital and fetal and infant death among residents of low-income areas (OR: 0.75, 95% CI 0.70 to 0.80 ; OR: 0.82, 95% CI 0.82 to 0.94). We also found strong protective associations when restricting to NH black persons only for fetal death (OR: 0.81, 95% CI 0.71 to 0.93) and infant death (OR: 0.79, 95% CI 0.70 to 0.90).

Cross-class social connections may play an important but underexamined role in promoting maternal and infant health, particularly within disadvantaged communities.