Young maternal age and smoking during pregnancy as risk factors for gastroschisis.

Three maternal risk factors (maternal age, cigarette smoking, and infant's month of birth) have been reported to be associated with fetal gastroschisis. In order to study these risk factors further, a prospective population-based study was designed, using 62,103 consecutive second-trimester singleton pregnancies enrolling in a maternal serum alpha-fetoprotein screening program between January 1, 1980 and April 30, 1989. Gastroschisis occurred in 21 of those pregnancies. Pregnancies in women younger than 20 years of age were at 7.3 times greater odds for being affected with gastroschisis than pregnancies in women aged 25 or older (95% confidence interval 2.4 to 22). For pregnant women aged 20 to 24 years, the odds were 1.9 times greater (95% confidence interval 0.7 to 5.0). Pregnant women who smoked cigarettes were at 2.1 times greater odds than non-smokers (95% confidence interval 0.9 to 4.8). When these smoking data were combined with smoking data from two other published studies, the consensus odds ratio was 1.6 (95% confidence interval 1.2 to 2.2). Infant's month of birth was not associated with gastroschisis. Evidence from the present study and other published studies clearly establishes a greater risk for fetal gastroschisis in pregnant women younger than age 20, even after adjustment for smoking status. Cigarette smoking also appears to be a risk factor, when data from this and two previously published studies are combined.