Are individual‐level risk factors for gastroschisis modified by neighborhood‐level socioeconomic factors?

Background: Two strong risk factors for gastroschisis are young maternal age (<20 years) and low/normal pre‐pregnancy body mass index (BMI), yet the reasons remain unknown. We explored whether neighborhood‐level socioeconomic position (nSEP) during pregnancy modified these associations. Methods: We analyzed data from 1269 gastroschisis cases and 10,217 controls in the National Birth Defects Prevention Study (1997–2011). To characterize nSEP, we applied the neighborhood deprivation index and used generalized estimating equations to calculate odds ratios and relative excess risk due to interaction. Results: Elevated odds of gastroschisis were consistently associated with young maternal age and low/normal BMI, regardless of nSEP. High‐deprivation neighborhoods modified the association with young maternal age. Infants of young mothers in high‐deprivation areas had lower odds of gastroschisis (adjusted odds ratio [aOR]: 3.1, 95% confidence interval [CI]: 2.6, 3.8) than young mothers in low‐deprivation areas (aOR: 6.6; 95% CI: 4.6, 9.4). Mothers of low/normal BMI had approximately twice the odds of having an infant with gastroschisis compared to mothers with overweight/obese BMI, regardless of nSEP (aOR range: 1.5–2.3). Conclusion: Our findings suggest nSEP modified the association between gastroschisis and maternal age, but not BMI. Further research could clarify whether the modification is due to unidentified biologic and/or non‐biologic factors. [ABSTRACT FROM AUTHOR]