Variation in birth outcomes by mother's country of birth among non-Hispanic black women in the United States.

Rates of prematurity (PTB) and small-for-gestational age (SGA) were compared between US-born and foreign-born non-Hispanic black women. Comparisons were also made between Sub-Saharan African-born and Caribbean-born black women and by maternal country of birth within the two regions. Comparisons were adjusted for sociodemographic, health behavioral and medical risk factors available on the birth record. Birth record data (2008) from all states (n = 27) where mother's country of birth was recorded were used. These data comprised 58 % of all singleton births to non-Hispanic black women in that year. Pearson Chi square and logistic regression were used to investigate variation in the rates of PTB and SGA by maternal nativity. Foreign-born non-Hispanic black women had significantly lower rates of PTB (OR 0.727; CI 0. 726, 0.727) and SGA (OR 0.742; CI 0.739-0.745) compared to US-born non-Hispanic black women in a fully adjusted model. Sub-Saharan African-born black women compared to Caribbean-born black women had significantly lower rates of PTB and SGA. Within each region, the rates of PTB and SGA varied by mother's country of birth. These differences could not be explained by adjustment for known risk factors obtained from vital records. Considerable heterogeneity in rates of PTB and SGA among non-Hispanic black women in the US by maternal nativity was documented and remained unexplained after adjustment for known risk factors.