Ethnicity, nutrition, and birth outcomes in nulliparous women

OBJECTIVE: Ethnic differences in birth outcomes are well established, but it is not clear whether differences in nutrition may partly explain unaccounted differences in birth outcomes. Our purpose was to evaluate the relationship of nutrition to ethnic differences in birth outcomes. STUDY DESIGN: This was a multicenter, prospective study of 4589 healthy nulliparous women who were enrolled in the Calcium for Preeclampsia Prevention trial conducted from 1992 to 1995. Main outcome measures were birth weight, gestational age at delivery, preterm birth, and small for gestational age birth after the data were controlled for maternal characteristics and intake of total calories, protein, carbohydrate, fat, and 13 vitamin and mineral constituents that were obtained from a 24-hour recall at 13 to 21 weeks' gestation. RESULTS: Black and non-Hispanic white women differed significantly in birth outcomes, with odds ratios of 2.06 (95% confidence interval, 1.48-2.86) for small for gestational age and 1.38 (95% confidence interval, 0.98-1.95) for preterm birth, after adjustment for maternal characteristics. These odds ratios were hardly changed by the further adjustment for all nutritional variables, even though there were substantial nutritional differences between black and white women. Differences in birth outcomes between Hispanic and non-Hispanic white women were small. Hispanic women who spoke only Spanish were better nourished than those Hispanic women who spoke English, but this had only a modest effect on birth outcomes. CONCLUSION: Nutritional variation among women in the United States does not appear to have a significant role in the explanation of ethnic differences in birth outcomes.