Maternal smoking during pregnancy and limb reduction malformations in Sweden.

OBJECTIVE: This study was undertaken to investigate a possible connection between different types of limb reduction defects and maternal smoking during pregnancy.

METHODS: With the use of the Swedish health registries, 610 cases of limb reduction malformations were selected from among 1 109 299 infants born between 1983 and 1993 with known smoking exposure in early pregnancy. Confounders such as maternal age and parity were controlled for with the use of the Mantel-Haenszel technique.

RESULTS: The odds ratio for any maternal smoking among all cases of limb reductions was 1.26 (95% confidence interval = 1.06, 1.50). The main subgroups of limb reduction defects showed similar odds ratios, but in longitudinal reduction defect, only unilateral cases showed an association with maternal smoking.

CONCLUSIONS: This study supports an association between maternal smoking and limb reduction malformations, but further work is needed before a causal inference can be made.