Smoking during pregnancy and congenital limb deficiency.

OBJECTIVE--To examine genetic and environmental factors in the origin of isolated congenital limb deficiencies. DESIGN--Case-control study with 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 anomalies). SETTING--The database of the Hungarian Congenital Abnormality Registry, 1975-84, complemented by three other sources of ascertainment (1,575,904 births). SUBJECTS--537 case-control pairs; 392 positive controls. MAIN OUTCOME MEASURES--Smoking during pregnancy, congenital limb deficiencies. RESULTS--The adjusted rate of smoking during pregnancy was significantly higher in the mothers of cases of terminal transverse defect (relative odds 1.48; 95% confidence interval 0.98 to 2.23; P = 0.017). This finding supports the hypothesis of vascular disruption as a cause of congenital limb deficiency. CONCLUSIONS--Maternal smoking during pregnancy raises the relative odds for terminal transverse limb deficiencies.