Selected acculturation factors and birth defects in the National Birth Defects Prevention Study, 1997-2011.

Background: Acculturation has been examined with respect to various pregnancy adverse outcomes, including birth defects. Given the mixed and limited findings on the association between nativity and birth defects, we sought to further explore parental nativity and years lived in the U.S. across a range of defects.

Methods: Data from the National Birth Defects Prevention Study were used for this analysis. Infants with one of 46 major isolated birth defects (30 noncardiac/16 cardiac conditions) and infants without birth defects (controls) born during 1997-2011 were included. We examined parental nativity (foreign-born mothers, fathers, and both parents combined compared to a referent of both U.S.-born parents) and the number of years lived in the U.S. (≤5/6+ years). Descriptive statistics and logistic regression analyses were performed to estimate crude/adjusted odds ratios and 95% confidence intervals.

Results: Compared to U.S.-born mothers, foreign-born mothers tended to be older (25+ years), of Hispanic or Other race/ethnicity and were less likely to have reported drinking, smoking, illicit drug use, or having taken folic acid. In the adjusted analysis, seven findings among both parents reporting a foreign-birth were significant, including an increased association with spina bifida, anotia/microtia, and diaphragmatic hernia (aORs range: 1.3-1.7), and a reduced association with craniosynostosis and gastroschisis (aORs = 0.7). A generally protective effect was observed among foreign-born subjects living in the U.S. ≤5 years.

Conclusions: We found that nativity was associated with some selected isolated defects, although the direction of effect varied by phenotype and by a number of years residing in the U.S.