Fetal growth impairment from smoking--is it influenced by maternal anthropometry?

Background: It has been suggested that the effect of maternal smoking on fetal growth is partly mediated through nutritional factors.

Objective: To assess the effects of maternal smoking on birthweight in term pregnancies among mothers with different anthropometric stature.

Design: A prospective study from early pregnancy of healthy parous women and their infants.

Setting: Three Scandinavian university hospitals covering all deliveries from well defined geographic areas.

Subjects: Smoking (774) and non-smoking (325) mothers, para 1 and 2 and with > 36 weeks gestational length.

Main outcome measure: Birthweight.

Results: Maternal age, smoking, pre-pregnancy weight, height, body mass index and pregnancy weight gain all independently influenced birthweight. Smoking mothers had significantly lower pre-pregnancy weight and lower body mass index compared to nonsmoking mothers. The negative influence of smoking on birthweight appeared to be uniformly distributed throughout all the different maternal height and weight groups.

Conclusions: Birthweight was negatively related to amount cigarettes smoked per day, and no protective effect could be demonstrated from higher maternal weight, pregnancy weight gain or body mass index.