engleski

Maternal smoking during pregnancy and birth weight in European cohorts: The HEALS project

Background: Several studies have indicated that tobacco smoking changes the intrauterine environment that largely affects fetal growth. Low birth weight due to maternal smoking has been found to increase with maternal diseases like diabetes, maternal weight gain and other associated complications. Additional plausible confounders such as, socio-economic status, ethnic groups, sex of the child, alcohol consumption etc. are also found to have a synergistic effect on birth- weight. The aim of this study was to assess the potential impact of maternal smoking during pregnancy on birth- weight, taking into account clinical information and other related factors. Methods: The study included 17383 individuals from different pre- existing cohorts ( EPITeen, Generation 21, REPROPL, CCM, PHIME and EDEN) across multi- centers of six European countries, namely Portugal, Poland, Italy, Croatia, Slovenia and France respectively. A stratified logistic regression analysis was performed to determine the association between birth-weight and maternal smoking habits. In addition to maternal diseases during pregnancy, the effect of maternal smoking on birth weight was simultaneously controlled for sex of child, maternal weight at the end of pregnancy, maternal drinking habits, ethnic group, work position and educational level of mother, and socio-economic crowding index. Due to the presence of missing values, maximum- likelihood method has been used for multiple imputation in the data. Results: 15.79% of the pregnant mothers were regular smokers, 8.15% of newborns weighed less than 2.5 kg at birth. 7.05% of infants were born with low birth-weight (LBW) in case of non-smoking mothers, whereas 12.44% of LBW infants were documented for mothers who smoked during pregnancy. The number of infants with LBW was found to rise with the increasing number of cigarettes smoked by the mothers during pregnancy. 8.02%, 8.92% and 9.25% of LBW was observed when mothers smoked up to 5, 11 and greater than 11 cigarettes per day respectively. Maternal weight was also found to affect birth weight prominently (OR= 1.06 ; 95% CI = 1.02, 1.11), along with other factors like infectious diseases during pregnancy. After adjusting for confounders, maternal smoking during pregnancy had a significant association with LBW (OR= 1.95 ; 95% CI=1.58, 2.22). Similar findings were observed when sub-samples of the data were considered on the basis of geographic origins. Conclusions: Using large data from pre-existing cohorts of different European countries, our study confirms a prominent birth weight reduction with maternal smoking. This finding supports the biological explanation of placental deformation due to smoking that leads to reduced birth weight and other neonatal complications.

Maternal smoking ; pregnancy ; birth weight ; European cohorts ; The HEALS project

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