Maternal birthplace, ethnicity, and low birth weight in California

Background: Although immigrants to the United States are usually ethnic minorities and socioeconomically disadvantaged, foreign-born women generally have lower rates of low birth weight infants than do US-born women. Objective: To measure the relationship between maternal birthplace, ethnicity, and low birth weight infants. Design: Retrospective cohort study of birth certificate data. Setting: California, 1992. Subjects: Singleton infants (n = 497 868) born to Asian, black, Latina, and white women. Main Outcome Measures: Very low birth weight (500-1499 g), moderately low birth weight (1500-2499 g), and normal birth weight (2500-4000 g, reference category). Results: Foreign-born Latina women generally had less favorable maternal characteristics than US-born Latinas, yet foreign-born Latina women were less likely to have moderately low birth weight infants (odds ratio, 0.91; 95% confidence interval, 0.86-0.96) than US-born Latinas after adjusting for maternal age, education, marital status, parity, tobacco use, use of prenatal care, and gestational age. While foreign-born Asian women generally had a less favorable profile of maternal characteristics than US-born Asians, there was no statistically significant difference in the odds of very low birth weight or moderately low birth weight infants between foreign- and US-born Asian women. Foreign-born black women had more favorable maternal characteristics than US-born women, but there was no significant nativity difference in very low birth weight or moderately low birth weight between foreign- and US-born black women after adjusting for maternal and infant factors. Conclusions: The relationship between maternal birth-place and low birth weight varies by ethnicity. Further study is needed to understand the favorable pregnancy outcomes of foreign-born Latina women.