Randomised trial of nicotine patches in general practice: results at one year

factor and terminal transverse defect. It would be necessary to test this finding in a study with the measurement of cigarette related markers, such as maternal serum or urine cotinine concentrations. The low relative risk (about 1 5) for such a common exposure as smoking has important public health implications for congenital limb deficiency in the population (the attributable risk is about 14%). This risk is obviously more important than the association of congenital limb deficiency with chorionic villus sampling.2"28 The confirmed teratogenic effect of maternal smoking may be a further strong indication for public health interventions aimed at preventing smoking during pregnancy.