Impact of Immigration and Duration of Residence in US on Length of Gestation Among Black Women in Newark, New Jersey.

Little is known about pregnancy outcomes of black immigrant women to the US. We surveyed 447 black women post-partum in two hospitals in Newark, NJ. Length of gestation was obtained from medical records. Covariates and information on immigration were collected by in-person interview. Risks ratios for preterm birth (< 37 weeks) comparing immigrant to US-born women were calculated using log-binomial regression. Associations with gestational age at delivery were estimated using linear regression. Multivariable models adjusted for socioeconomic and social/behavioral variables. Immigrant women relative to US-born women had a 60% lower risk of preterm birth (adjusted risk ratio = 0.4; 95% confidence interval (CI) 0.2, 0.8) and longer gestation (adjusted difference = 1.4 weeks, 95%CI 0.6, 2.1). Gestation was 1.9 weeks longer for recent immigrants compared to US-born women (95%CI 0.2, 3.6), whereas for those who lived in the US for at least 10 years there was no difference. The healthy immigrant effect found among black immigrants may erode with time in the US.