Adverse pregnancy outcomes such as low birth weight are increased among US-born mothers of Mexican descent compared with immigrant mothers born in Mexico. It is unknown whether adverse reproductive outcomes change among Mexican immigrants after only 5 years of US residence. The authors conducted a study of 1,114 Mexican immigrant mothers and their infants in two California counties. The relation between US residence status and birth outcomes was examined, controlling for sociodemographic factors and maternal behaviors. Long-term immigrants who have lived in the United States for more than 5 years were more likely to deliver preterm infants (odds ratio (OR) = 1.9, 95% confidence interval (CI) 1.1-3.3) and low birth weight infants (OR = 1.5, 95% CI 0.8-2.7) than newcomers who have lived in the United States for 5 years or less. Long-term immigrants had higher parity, more pregnancy complications, and fewer planned pregnancies, and were more likely to smoke than newcomers. After controlling for confounders, the effect of residence status on preterm delivery was of borderline significance (adjusted OR = 1.8, 95% CI 1.0-3.2). Pregnancy complications was an intervening variable between residence statue and preterm delivery. Length of US residence is associated with an increase in low birth weight via a decrease in gestational age rather than intrauterine growth retardation.

Emigration and immigration Mexican Americans Birth weight infant, low birth weight

immigrant pregnancy complication Pregnancy Complications Population Surveillance human controlled study Time Factors Logistic Models Infant, Premature length of stay Mexico United States Infant, Newborn female Multivariate Analysis pregnancy Infant, Low Birth Weight Article low birth weight pregnancy outcome Support, Non-U.S. Gov't major clinical study adult prematurity Emigration and Immigration parity Birth Weight medical geography gestational age USA, California residency effect birth outcome Mexican Americans