Mother's smoking during pregnancy linked to early puberty in children

Smoking during pregnancy increases the children's risk of attaining puberty earlier, according to a new study.

The study, published in the American Journal of Epidemiology, maternal smoking during pregnancy was associated with younger age at all pubertal milestones in sons. In daughters, maternal smoking during pregnancy was associated with younger age at breast development, pubic hair development, menarche, and acne but not with axillary hair. In utero exposure to tobacco smoke may advance the timing of puberty.

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Nis Brix, Department of Public Health, Section for Epidemiology, Aarhus University, Aarhus, Denmark, and colleagues conducted the study to explore the possible associations between maternal smoking during pregnancy and pubertal development in sons and daughters.

Key Findings:

• In sons, smoking in pregnancy was associated with earlier genital development, pubic hair development, and voice break.


• In daughters, smoking was associated with earlier breast development, pubic hair development stage 3 to 5, and menarche (−3.1, 95% CI: −4.0, −2.3).


• 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.


• Fetal exposure to tobacco smoke advances the timing of puberty in boys and girls.

"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 Nis Brix.

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.

For the study, the researchers analyzed 15,819 pregnant women and their children. 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.

"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 is 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.

For more information follow the link: https://doi.org/10.1093/aje/kwy206