INCREASED RISK FOR TRANSVERSE DIGITAL DEFICIENCY AFTER CHORIONIC VILLUS SAMPLING - RESULTS OF THE UNITED-STATES MULTISTATE CASE-CONTROL STUDY, 1988-1992

Although numerous infants have been reported with transverse limb defi ciencies after their mothers had undergone chorionic villus sampling ( CVS), it has been unclear whether the procedure caused these defects. We report the results of the first multistate case-control study to as sess and quantify the risk for specific limb deficiencies associated w ith CVS. Case subjects were 131 infants with nonsyndromic limb deficie ncy ascertained from 7 population-based birth defect surveillance prog rams, and born from 1988-1992 to mothers 34 years of age or older. Con trol subjects were 131 infants with other birth defects. We ascertaine d exposure to CVS from medical records and maternal and physician ques tionnaires. We assessed rates and timing of exposure to CVS, and estim ated relative and absolute risks for anatomic subtypes of limb deficie ncy. The odds ratio for all types of limb deficiency after CVS from 8- 12 weeks' gestation was 1.7 (95% confidence interval, 0.4-6.3). For sp ecific anatomic subtypes, the strongest association was for transverse digital deficiency (odds ratio = 6.4; 95% confidence interval, 1.1-38 .6). The risk for transverse digital deficiency increased with earlier gestational exposure (P < 0.01 for trend). We estimated that the abso lute risk for transverse digital deficiency in infants after CVS was 1 per 2,900 births (0.03%). Exposure to CVS was associated with a sixfo ld increase in risk for transverse digital deficiency. The causality o f this association is supported by its strength, specificity, biologic plausibility, and consistency with the results of previous studies. A lthough some centers already inform patients about risk for limb defic iency, this study quantifies the magnitude of risk associated with CVS from 8-12 weeks' gestation. (C) 1995 Wiley-Liss, Inc.