If the mother smokes during pregnancy, there is a risk of her children going into puberty earlier. This is shown by a major study from Aarhus University which has just been published in the international journal American Journal of Epidemiology.

If it is difficult to quit smoking during pregnancy, then here is yet another good reason to stop. A research group from the Department of Public Health at Aarhus University, links the mother's smoking during pregnancy together with when her children enter puberty.

"We found that children of mothers who had smoked more than ten cigarettes a day during pregnancy, on average entered puberty three to six months earlier than the children of non-smokers," says PhD student Nis Brix, who is one of the researchers behind the study.

The study is one of the largest puberty studies worldwide, and the results are based on the survey "Better health for generations" from the Statens Serum Institut in Denmark.

May lead to diseases later

A total of 15,819 pregnant women and their children participated in the study. During pregnancy, the women were asked about their smoking habits. Then, the children were followed and filled in 83,810 questionnaires about their pubertal development from the age of eleven and every six months thereafter.

The researchers find early puberty worrisome.

"Early puberty can be associated with an increased risk of a number of diseases as an adult, such as obesity, diabetes, cardiovascular diseases and certain types of cancer," says Nis Brix. Together with his colleagues, he is working to identify the causes of puberty to be able to prevent it occurring.

"It is known that smoking is harmful to the unborn fetus. Smoking is, among other things, associated with an increased risk of low birth weight, premature birth and increased mortality. There are thus a wide range of other good reasons to give up smoking before pregnancy. We hope that our results can be used as another motivating factor to stop smoking among women who are planning on becoming pregnant," says Nis Brix.