Economic connectivity and clustering: The influence of social connections on maternal and infant health.

Recent influential work in the US finds that bridging capital (i.e., friendships across socioeconomic strata) appears to increase upward economic mobility over the life course. Examinations of the role of these social connections on health, however, remain relatively unexplored. We exploit a recent effort which made publicly available ZIP-level measures of bridging capital and bonding capital (i.e., depth of friend networks within the same stratum) using Facebook information on >70 million Americans. We test in California (8 million births; California Birth Cohort File 2005 to 2021) the relation between ZIP-level social connections and a wide range of maternal and infant health outcomes, including fetal and infant death, birthweight, preterm birth, pre-pregnancy smoking, and body mass index. Generalized estimating equation methods controlled for individual-level covariates as well as spatial clustering of observations. Findings indicate strong protective associations between bridging capital and the risk of fetal death, infant death, preterm birth, pre-conception maternal smoking, maternal body mass index, and infant birthweight. These protective associations are much greater in magnitude than other ZIP-level measures commonly used in the literature to assess economic and structural advantage. Bonding capital, however, appears detrimental for maternal pre-pregnancy smoking and body mass index. The potential of bridging ties (i.e., across socioeconomic strata) in promoting maternal and infant health should warrant much more scholarly consideration than it currently receives.