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Influence of nativity on neonatal survival of Black twins in the United States.

OBJECTIVE
To determine the association between maternal nativity and neonatal survival of twins among Black mothers.


METHODS
We conducted a retrospective cohort study of twin live births to Black mothers in the United States from 1995 through 1998. We compared levels of overall, early, and late neonatal mortality between twins of US-born and those of foreign-born Black mothers by using hazard ratios generated from a Cox Proportional Hazards Regression model. We adjusted for dependence of observations within twin clusters by means of the Robust Sandwich Estimator.


RESULTS
A total of 70,884 individual twin live births to US-born (64,035) and foreign-born (6,849) mothers were analyzed. Twins of US-born mothers had a 23% higher likelihood of dying within the neonatal period compared to those of foreign-born mothers (hazard ratio [HR]=1.23; 95% confidence interval [CI]=1.04-1.46). The disparity in neonatal demise occurred exclusively in the early neonatal period (HR=1.29; 95% CI, 1.06-1.50), with mortality indices comparable in the late neonatal period (HR=0.96; 95% CI, 0.68-1.35). Low and very low birth weight (P<.0001), preterm and very preterm (P<.0001), and small-for-gestational-age neonates (P<.0001) were more prevalent among twins of US-born mothers.


CONCLUSIONS
Compared to those of foreign-born, twins of US-born Black mothers experienced higher mortality in the neonatal period. The mortality disadvantage resulted mainly from lower gestational age at birth and the preponderance of small-for-gestational-age babies among US-born Black mothers.