Tobacco: mothers who smoked during pregnancy have bigger children

Children whose mothers smoked during pregnancy could be faced with an increased risk of overweight at age 8 years, according to the results of a major study.

Dr. Aimin Chen of the U.S. National Institute of Medical and Environmental Sciences, and colleagues collected data on 34,866 children born between 1959 and 1965 and followed until the age of 8 years. Mothers responded to questions regarding their possible smoking during pregnancy and the weight and height of children were measured when they were aged 1, 3, 4, 7 and 8.

Overall, children of smokers were more likely to be overweight or on the verge of becoming the age of 8. Every ten cigarettes smoked per day by the mother during pregnancy increased the risk by 17%, report scientists.

The link between prenatal smoking and weight of the child remained after adjustment for several factors, such as family income, maternal weight and level of education.

This observation could be explained by the low birth weight of children whose mothers smoked during pregnancy. Children with low birth weight often go through a period of rapid "catch-up" growth, which could make them more vulnerable to excess weight a few years later, according to Dr. Chen.

Another possibility would be a sort of "cessation" of children of smoking after birth, which could lead, as for smokers looking to quit, modification reflexes appetite control.