AbstractTo identify risk factors for gastroschisis other than drug use in pregnancy, an analysis of data collected in a case‐control surveillance program of birth defects (1976‐1990) was conducted. Drug use is considered in Werler et al.,Teratology, 45:361‐367, 1992. Maternal demographic, reproductive, and medical factors, and first trimester environmental exposures, were compared between 76 gastroschisis cases and 2,581 malformed controls. A strong inverse association was found for maternal age: relative to women 30 years or older, relative risks for 25‐29, 20‐24, and<20‐year‐old women were 1.7, 5.4, and 16, respectively. Multivariate relative risks (and 95% confidence intervals) for alcohol use were as follows: for 1‐5 drinks per week, 1.6 (0.7‐3.4); for ⩾6 drinks per week, 2.5 (0.9‐6.8); for a maximum of 1‐4 drinks at any one time, 0.8 (0.4‐1.6); and for a maximum of ⩽5 drinks, 2.8 (1.2‐6.5). With the effect of age taken into account, no associations were identified for cigarette smoking, consumption of caffeinated or decaffeinated coffee, unplanned pregnancy, 12 or less years of education, or a parity of two or more. Other medical and reproductive factors, including weight gain, vaginal bleeding, nausea or vomiting, influenza, “other” infection, and history of spontaneous abortion or elective a