Title: Is it a Hispanic Paradox? Examining the effect of individual and neighborhood factors on birth outcomes
Description: The Hispanic birthweight paradox, whereby Hispanic women exhibit a comparable or lower risk of bearing a low birthweight infant than their white counterparts despite relative socioeconomic disadvantage, has been observed across a number of research studies. However, the majority of evidence for the paradox has focused on Hispanics in aggregate form or on populations with primarily Mexican ancestry and has relied largely on outcome measures with important methodological shortcomings. Furthermore, studies have identified the variation of birthweight risk among Hispanics by nativity, maternal education and neighborhood composition, but the evidence has been scarce and inconsistent. The overall goal of this dissertation was to investigate the Hispanic health paradox with relation to measures of birthweight and infant size in births to women residing in New York City aged 20 years and older, using birth records for years 2003 through 2007 collected by the Office of Vital Statistics of the New York City Department of Health and Mental Hygiene (N=460,881).

The main outcomes of interest in this study were mean birthweight, low birthweight (LBW, defined as < 2500 grams versus ≥ 2500 grams) and small for gestational age (SGA, calculated as the 10th percentile for birthweight at each week of gestational age and by sex). Multilevel logistic models with random effects were used to estimate odds ratios for the association between race/ethnicity and measures of birthweight and infant size, while controlling for individual-level and contextual factors and accounting for the correlation between observations within the same neighborhood. Analyses were conducted with Hispanics as an aggregate group as well as with race/ethnic-nativity subgroups. In addition, effect measure modification by maternal education and by neighborhood proportion of Hispanic population (NPHP) were examined. This research confirmed the Hispanic paradox in SGA analyses for Hispanics overall and for both U.S.-born and foreign-born Hispanics, but not in analyses with LBW or with mean birthweight.

As compared to white women, black women exhibited 50% greater risk (OR:1.50;95%CI:1.45,1.55) and Hispanic women comparable risk (OR:1.03;95%CI:1.00,1.06) of having an SGA infant, in a fully adjusted model. With regard to LBW, the risk was more than double for black women (OR:2.25;95%CI:2.16,2.35) and close to 50% greater for Hispanic women (OR:1.46;95%CI:1.40,1.53) as compared to that of their white counterparts. In addition, the mean birthweight of infants born to Hispanic women was significantly lower compared to those born to white women. Furthermore, the relationship between race/ethnicity and all three measures of birthweight and infant size varied by maternal nativity status (p<0.0001), with infants of foreign-born women experiencing more favorable outcomes relative to their U.S.-born counterparts. The paradox with SGA was also apparent across most Hispanic race/ethnicity-nativity subgroups, The odds were greatest among black and Puerto Rican women overall (OR:1.52;95%CI:1.47,1.57 and OR:1.17;95%CI:1.13,1.22, respectively) and lowest among Mexican and South American women overall, (OR:0.91;95%CI:0.87,0.95 and OR:0.85;95%CI:0.80,0.89) as compared to white women in a fully adjusted model.

The odds of SGA for infants born to Dominicans, Central Americans and Cubans in the fully adjusted model were similar to those born to whites. In addition, SGA varied by maternal nativity status (p<0.0001), with more favorable SGA odds observed among infants of most foreign-born women, as compared to whites. The exception was U.S.-born Puerto Ricans who consistently exhibited elevated risk of SGA relative to whites. The association of race/ethnicity-nativity with SGA varied by maternal educational attainment (p<0.0001), but the influence varied by subgroup. The observed advantage of foreign birth was stronger among less educated women of all Hispanic subgroups other than Puerto Ricans and Cubans. Similarly, the variation of SGA risk by neighborhood proportion of Hispanic population (NPHP) differed across subgroups (p<0.0001). NPHP did not appear to influence the association between race/ethnicity-nativity and SGA in a consistent pattern, but among black women and US-born Puerto Rican women greater NPHP was associated with a higher risk of SGA.

Findings from this study underscore the importance of using SGA an accurate measure of infant size and of conducting analyses disaggregating race/ethnicity and nativity subgroups. Future research should focus on factors that contribute to the resilience of Hispanic subgroups in the face of adverse economic circumstances, such as the role of social support networks and acculturation. Greater understanding of the salubrious circumstances that lower the risk of adverse birth outcomes has major public health benefits, especially for a wide-ranging population of mothers, Hispanic and non-Hispanic, and their infants.