The purpose of this study was to determine the effect of maternal pre-pregn
ancy body mass index (BMI) and maternal smoking habits on neonatal birth we
ight. We reviewed 10,240 normal singleton term pregnancies between 1985 and
1995 at the University Department of Obstetrics and Gynecology, Vienna. Bi
rth weights of infants of overweight smokers were greater than those of smo
kers in general and similar to birth weights of nonsmokers, but smoking did
have a fetal growth-retarding effect in overweight smoking mothers. Infant
s of underweight mothers who increased their daily cigarette consumption du
ring pregnancy had significantly lowest birth weight, Our results suggest t
hat the negative effects of smoking during pregnancy cannot be mitigated by
a higher pre-pregnancy BMI and/or an improved weight gain during pregnancy
. Especially the infants of underweight mothers benefit from their mothers'
decision to cease smoking. Copyright (C) 2000 S. Karger AG, Basel.