Does Maternal Origin Impact Hispanic Preterm Infant Mortality?

Research study background

A national retrospective cohort study led by neonatology experts at Children’s Hospital Colorado has uncovered new insight into infant mortality rates (IMR) within subgroups of U.S.-born preterm Hispanic infants. Accounting for nearly one out of every four U.S. births, the Hispanic birthing population has origins in more than 20 countries and regions. While past research indicates encouraging trends for IMR in infants born to Hispanic mothers compared to non-Hispanic Black and non-Hispanic White mothers, few studies have disaggregated Hispanic birthing population data and explored outcomes by maternal regional or national origin.

The research team reviewed birth and death certificate data and clinical and sociodemographic covariates for 891,216 live born preterm infants with Hispanic maternal ethnicity born between 2005 and 2014 They analyzed IMR (death of a live-born infant within the first year of life) across Hispanic subgroups by country/region of origin, examined how maternal nativity influences IMR and explore how differences in maternal nativity IMR varies by Hispanic subgroup.

Across subgroups, investigators found significant differences in sociodemographic and clinical characteristics. Cuban mothers had the highest education and hypertension rates, while Puerto Rican mothers had the highest diabetes rates. Cuban mothers also had the highest rate of multiple births. The preterm IMR was 29.6 per 1,000 live births in the overall cohort before and after adjustments for maternal and infant characteristics. Among subgroups, there were many differences in unadjusted and adjusted preterm IMR. After adjusting for maternal and infant characteristics, infants of Puerto Rican mothers had lower odds of preterm infant mortality, while infants of Cuban and Central/South American mothers consistently had lower odds compared to those of Mexican mothers. Further, smoking rates varied widely among subgroups.

Multiple differences in characteristics within the Hispanic mothers were observed among U.S.-born mothers versus foreign-born groups. Foreign-born mothers were older and had higher rates of diabetes, while U.S.-born mothers had higher education and smoking rates (4.5% vs. <1%). Preterm IMR didn’t vary between U.S.-born and foreign-born overall but varied by nativity status within some subgroups. Infants of U.S.-born Mexican mothers had higher IMR compared to Cuban and Central/South American mothers. Adjusted IMR differences by nativity were mostly insignificant, except for higher rates among U.S.-born mothers of other or unknown origin.

Clinical implications

While there were some limitations, this study uncovered important information on the rates of infant mortality among preterm infants from different maternal Hispanic country and region subgroups, as well as whether their mothers were born in the U.S. or abroad.

This research highlights the unique characteristics and diversity of the Hispanic birthing population. It also emphasizes how analyzing detailed data on social determinants for these subgroups may help improve understanding of factors driving poor perinatal outcomes and aid in developing more effective, targeted interventions for certain groups with the highest rates of adverse outcomes.