Objective: We examined adverse birth outcomes among Mexican-Americans to determine the effect of country of maternal birth, a measure of acculturation.
Design: We conducted a retrospective cohort analysis of birth outcomes among 4800 Mexico-born and 4800 US-born Mexican-American women using Washington State birth certificate data from 1989 to 1994. Length of residence at current address was used to help refine our measure of acculturation.
Results: US-born women had a slightly increased risk of preterm birth relative to Mexico-born women [relative risk (RR) 1.18, 95% confidence interval (CI) 1.04-1.33]. Among Mexico-born women, the risk of preterm birth increased with greater duration of current residence.
Conclusions: US-born Mexican-American women had a slightly increased risk of preterm birth despite having more adequate prenatal care, more education, and higher socioeconomic indicators. This may be due to acculturation factors, such as earlier pregnancy, loss of social support systems, and increased smoking or alcohol use. Reducing this risk depends on recognition among health care workers and policy-makers of the potential influence of acculturation on health in this population.