Smoking during pregnancy increases the risk of asthma can skip a generation

The risk of childhood asthma appears to be increasing not only under the influence of maternal smoking, but when the grandmother of the child has smoked during pregnancy, report U.S. researchers specializing in "Chest" magazine.

Dr. Frank Gilliland and his colleagues at Department of Preventive Medicine, Keck School of Medicine in Los Angeles, came to this conclusion after comparing the data collected through telephone interviews conducted as part of a study called the Children's Health Study, about 338 young asthmatics aged less than five years and 570 matched participants serving as a comparison group and constituting a "control."

The analysis of this evidence allowed the authors to confirm that in utero exposure to maternal smoking not only increases the risk that the child receives a diagnosis of asthma during the first five years, but also that suffers from a persistent form of the disease (the risk is multiplied by 1.5 in both cases).

For children whose mothers smoked throughout pregnancy, the risk of asthma became 1.6 times greater than for those whose mothers had never smoked, while children whose mothers had stopped smoking prior to pregnancy showed no excess risk. No conclusions could be drawn about the impact of smoking cessation during pregnancy, as only 15% of participating smokers quit smoking during pregnancy, the authors note.

Having a grandmother who has smoked while she was pregnant with double the risk of mother grandchild or asthma, they also found, indicating that further studies are needed to confirm this observation.

According to them, this transgenerational association between smoking during pregnancy and excess risk of asthma for the second generation could be explained by the fact that the products of the combustion of tobacco cause DNA damage affecting the both immune function and detoxification mechanisms of the offspring that result, in the next generation, an increased susceptibility to asthma.