UCSF

Black women in the United States (US) have the highest risk of adverse perinatal outcomes, including preterm birth (PTB) and small for gestational age (SGA) birth, compared to women from all other race/ethnicities. Past research using samples of Black women living on the East Coast of the US has found variation in this risk by maternal nativity status, wherein foreign-born Black women are known to have a lower risk of adverse perinatal outcomes than US-born Black women. There is a paucity of research that contextualizes the rates of adverse perinatal outcomes among Black women through the lens of maternal nativity. This is particularly true for women on the West Coast of the US, where the immigrant ethnic composition is primarily African-born, compared to the largely Caribbean-born population on the East Coast. This dissertation utilizes all birth certificate and hospitalization data for singleton non-anomalous live-births to US- and African-born Black women in California from 2011-2020 to conduct three population-based studies examining the rates of PTB and SGA through the lens of maternal nativity, while exploring how African country of origin, exposure to neighborhood-level structural racism, and clinical factors may help to contextualize previously established nativity-based disparities.

In the first chapter, births to all African-born Black women are stratified by African country of origin and compared to the overall rate of adverse perinatal outcomes among US-born Black women, to determine whether the lower risk of adverse outcomes is uniform across all African countries of origin. We also evaluate whether differences in socio-demographic and clinical risk factors explain the overall disparities in PTB and SGA risk between US- and African-born Black women. We found heterogeneity in the risk of adverse birth outcomes among the African-born population, as Cameroon- and Eritrea-born Black women had larger differences, while Ghana-born Black women had smaller differences compared to US-born Black women. Overall, differences in socio-demographic and clinical risk factors between US- and African-born Black women explained a modest proportion of the nativity-based disparities in PTB (14.4%) and SGA (19.6%), although these proportions varied across African countries of origin.

In the second chapter, the aforementioned California birth data were merged with information from the American Community Survey to compute neighborhood-level measures of structural racism, operationalized as racial and economic neighborhood segregation. We assess the relationship between structural racism, maternal nativity, and adverse perinatal outcomes, finding that on average US-born Black women had an 81% greater risk of PTB and a 67% greater risk of SGA, compared to African-born Black women. US-born Black women were also more likely to live in areas with more structural racism than African-born Black women. Structural racism was associated with an increased risk of PTB and SGA for all Black women, however there was variation of this effect by maternal nativity.

In the third chapter, we focus on data pertaining to pregnancy and postpartum co-morbidities as well as clinical procedures within our dataset to assess the relationship between 14 clinical factors and the risk of PTB and SGA by maternal nativity. We found that on average US-born Black women had a higher prevalence of clinical factors associated with adverse perinatal outcomes. However, among African-born Black women the clinical risk factors conferred a heightened risk of PTB and SGA compared to US-born Black women, and therefore differences in the impact of these of clinical factors likely does not explain the heightened risk of PTB and SGA among US-born Black women.

Taken together, these findings emphasize the importance of considering maternal nativity when analyzing adverse perinatal outcome data for Black women. Analyses in California showed that nativity in Black women considered as an aggregate may mask heterogeneity in the risk of PTB and SGA. Future studies should continue to explore differences in the experience of racism across the life course as a core driver of inequities in adverse perinatal outcomes among Black women.