Association between maternal smoking and low birth weight in Switzerland: the EDEN study

ENGLISH :
Purpose: To study the association between maternal smoking during pregnancy and low birth weight (LBW), small-for-gestational-age birth weight (SGA) and preterm birth, and to quantify the population-attributable fractions for these outcomes in Switzerland. Methods: Data were gathered for all births in the Canton of Vaud (Switzerland) over a twelvemonth period in 19931994. LBW was defined as birth weight <2500 g, SGA as a birth weight <10th percentile for gestational age, and preterm birth as a birth occurring at a gestational age <37 weeks. Maternal smoking before and during pregnancy was recorded. Results: Of a total of 6284 singleton births, 303 (4.8%) were LBW, 731 (11.7%) were SGA, and 364 (5.8%) were preterm. 19.1% of the mothers reported smoking during pregnancy (smokers). Mean birth weight, adjusted for maternal age, parity, parents occupation and neonates sex and nationality, was lower by 190 g (95% confidence interval: 150220) in babies of smokers than those of non-smokers. Comparing smokers to non-smokers, the adjusted odds ratios were 2.7 (2.13.5) for LBW, 2.1 (1.72.5) for SGA and 1.4 (1.11.9) for preterm birth. Past smoking was not associated with the outcomes. Maternal smoking during pregnancy accounted for 22% (1529%) of all LBW babies in the population, 14% (1018%) of SGA and 7% (112%) of preterm births. Conclusion: Maternal smoking during pregnancy was closely associated with LBW, SGA and preterm birth. A large proportion of these perinatal outcomes could have been prevented in Switzerland if maternal smoking had been avoided. (Author' s abstract)