Ethnic differences in birth weight by gestational age: at least a partial explanation for the Hispanic epidemiologic paradox?

Objective The purpose of this study was to evaluate ethnic differences in low birth weight and gestational age–dependent birth weight. Study design A retrospective cohort study of 47,669 newborn infants was conducted with the use of the perinatal database of the Memorial Health Care System. Logistic regression was used to estimate the odds ratio for low birth weight by ethnic group, which took into account gestational age at delivery. Multiple linear regression models were then developed to predict ethnic differences in birth weight by gestational age. Results When compared with white women, the adjusted odds ratio for low birth weight in of Mexican origin women (1.16; 95% CI, 1.02-1.32) was substantially lower than that of African American women (2.21; 95% CI, 1.87-2.60). An analysis of birth weight by gestational age suggested that African American neonates were intrinsically smaller than Hispanic neonates (difference, 4.22%). Conclusion At least some of the differences in low birth weight that are noted among ethnic minorities may be attributable to ethnic differences in birth weight by gestational age.