Maternal asthma medication use and the risk of selected birth defects.

OBJECTIVES Approximately 4% to 12% of pregnant women have asthma; few studies have examined the effects of maternal asthma medication use on birth defects. We examined whether maternal asthma medication use during early pregnancy increased the risk of selected birth defects. METHODS National Birth Defects Prevention Study data for 2853 infants with 1 or more selected birth defects (diaphragmatic hernia, esophageal atresia, small intestinal atresia, anorectal atresia, neural tube defects, omphalocele, or limb deficiencies) and 6726 unaffected control infants delivered from October 1997 through December 2005 were analyzed. Mothers of cases and controls provided telephone interviews of medication use and additional potential risk factors. Exposure was defined as maternal periconceptional (1 month prior through the third month of pregnancy) asthma medication use (bronchodilator or anti-inflammatory). Associations between maternal periconceptional asthma medication use and individual major birth defects were estimated by using adjusted odds ratios (aOR) and 95% confidence intervals (95%CI). RESULTS No statistically significant associations were observed for maternal periconceptional asthma medication use and most defects studied; however, positive associations were observed between maternal asthma medication use and isolated esophageal atresia (bronchodilator use: aOR = 2.39, 95%CI = 1.23, 4.66), isolated anorectal atresia (anti-inflammatory use: aOR = 2.12, 95%CI = 1.09, 4.12), and omphalocele (bronchodilator and anti-inflammatory use: aOR = 4.13, 95%CI = 1.43, 11.95). CONCLUSIONS Positive associations were observed for anorectal atresia, esophageal atresia, and omphalocele and maternal periconceptional asthma medication use, but not for other defects studied. It is possible that observed associations may be chance findings or may be a result of maternal asthma severity and related hypoxia rather than medication use.