Perinatal & Pediatric
Why has gastroschisis been increasing over time and why is it more common in infants of young mothers? Rashida S. Smith-Webb* Rashida Smith-Webb Gary M. Shaw Peter H. Langlois Cynthia A. Moore Martha M. Werler National Birth Defects Prevention Study
Background: Gastroschisis, a severe abdominal wall defect, is more prevalent in infants of young mothers and has been increasing over the past decades. Various factors have been associated with an increased risk for gastroschisis independent of maternal age. However, studies have not systematically explored whether these factors can explain the time trend or age association. We examined whether factors previously associated with gastroschisis in the National Birth Defects Prevention Study (NBDPS) can explain the increasing prevalence over time and the inverse association with maternal age.
Methods: We used data from the NBDPS for gastroschisis cases and controls with delivery dates from 1997-2011. We calculated crude ORs for the time trend (birth years 2005-2011 vs. 1997-2004) and maternal age (<25 vs. 25+ years). We then evaluated the potential confounding effects of 18 factors separately (exposures: alcohol, cigarettes, illicit drugs, oral contraceptives, cold/flu+ fever, genitourinary infection, polycyclic aromatic hydrocarbons (PAHs), diet quality, BMI; reproductive: parity, interpregnancy interval; social: race, acculturation, income). We considered an exposure a confounder if the crude OR (cOR) for the time trend or maternal age changed by at least 10% in logistic regression models.
Results: The cOR for the time trend was 1.28; 95% CI: 1.14, 1.44, and was attenuated by at least 10% after adjustment for exposure to PAHs (any occupational OR = 1.12; 0.96, 1.30; cumulative across all jobs OR = 1.11; 0.96, 1.30). The cOR for young maternal age was 7.76 (6.71, 8.97). The maternal age OR was attenuated after adjusting for paternal age by 30% (OR = 5.43; 4.55, 6.48) and parity by 15% (OR = 6.62; 5.71, 7.68). Adjustment for other factors did not materially change the cORs for either the time trend or maternal age.
Conclusion: None of the parental exposures examined substantially accounted for the increasing time trend or the higher prevalence among younger mothers.