Nuclear radiation and prevalence of structural birth defects among infants born to women from the Marshall Islands

Background: With their unique history of exposure to extensive nuclear testing between 1946 and 1958, descendants of Marshall Island residents may have underappreciated genetic abnormalities, increasing their risk of birth defects. Methods: We conducted a retrospective cohort study of resident women with at least one singleton live birth between 1997 and 2013 in northwest Arkansas using state birth certificate data linked to data from the Arkansas Reproductive Health Monitoring System, a statewide birth defects registry. We calculated unadjusted and adjusted prevalence ratios (PR) and 95% confidence intervals (CI) from modified Poisson regression analyses for non-Hispanic (NH) whites, NH-blacks, Hispanics and Marshallese, using NH-whites as the reference group. Results: Of the 91,662 singleton births during the study period, 2,488 were to Marshallese women. Due to the relatively small number of Marshallese births, we could not calculate prevalence estimates for some defects. Marshallese infants had higher rates of congenital cataracts (PR = 9.3; 95% CI: 3.1, 27.9). Although the number of defects was low, Marshallese infants also had higher rates of truncus arteriosus (PR = 44.0; 95% CI: 2.2, 896.1). Conclusions: Marshallese infants may have increased risk of specific birth defects, but estimates are unstable because of small sample size so results are inconclusive. Larger population-based studies would allow for further investigation of this potential risk among Marshallese infants.