SMOKING DURING PREGNANCY AND CONGENITAL LIMB DEFICIENCY

Objective-To examine genetic and environmental factors in the origin o f isolated congenital limb deficiencies. Design-Case-control study wit h questionnaire at a family interview of cases of isolated congenital Limb deficiencies (six types), negative controls (matched for age, sex , and place of residence), and positive controls (cases of sentinel an omalies). Setting-The database of the Hungarian Congenital Abnormality Registry, 1975-84, complemented by three other sources of ascertainme nt (1 575 904 births). Subjects-537 case-control pairs; 392 positive c ontrols. Main outcome measures-smoking during pregnancy, congenital li mb deficiencies. Results-The adjusted rate of smoking during pregnancy was significantly higher in the mothers of cases of terminal transver se defect (relative odds 1.48; 95% confidence interval 0.98 to 2.23; P =0.017). This finding supports the hypothesis of vascular disruption a s a cause of congenital limb deficiency. Conclusions-Maternal smoking during pregnancy raises the relative odds for terminal transverse limb deficiencies.