Does the Epidemiologic Paradox Hold in the Presence of Risk Factors for Low Birth Weight Infants among Mexican-born Women in Colorado?

OBJECTIVES: To test whether foreign-born status confers a protective effect against low birth weight (LBW) outcomes among Mexican-origin women in Colorado. METHODS: Retrospective cohort study utilizing Colorado birth records from 1989-2004 for multivariate logistic regression analysis. The study population was 66,422 U.S.-born women of Mexican origin (USB) and 85,000 Mexican-born (MB) women with singleton births. RESULTS: Mexican-born women had 24.9% lower odds of LBW (OR 0.751 95% CI 0.782) than USB women. Mexican-born women had a higher prevalence of risk factors for LBW than their USB counterparts (anemia, cardiac disease, hypertension, inadequate prenatal care, less than high school education). After adjusting for these risk factors, MB women had 22.5% lower odds of having LBW infants than USB women (OR 0.775, 95% CI 0.73-0.81). CONCLUSIONS: This study supports the epidemiologic paradox of LBW; despite higher prevalence of risk factors, foreign-born status confers an overall protective effect against low birth weight outcomes.