Background and aims Studies in patients seeking medically assisted reproduction have shown that smoking reduces fertility, but little information is available in the general population. We assessed the associations between smoking and the number of children, childbearing planning and age at menopause in a representative sample of the population of Lausanne, Switzerland.
Methods Data from 6711 participants (3530 women, age range 35–75 years) collected between 2003 and 2006 and again in 2009 and 2012. Smoking status, number of offsprings and age of menopause were assessed.
Results Women who currently smoke had significantly less children than former or never smokers: the number of children per women (average±SD) was 1.38±1.05, 1.45±1.07 and 1.576±1.16, respectively (p<0.001). Women who currently smoke had their first child at an earlier age than the others: 26.7±5.2, 27.4±5.4 and 26.9±5.2 years old for current, former and never smokers, respectively, (p=0.01). Similar findings were found for men: number of children per men 1.475±1.16, 1.67±1.13 and 1.55±1.22 for current, former and never smokers, respectively (p<0.001); no difference was found regarding age at the first child. The difference persisted after multivariate adjustment (adjusted for age, body mass index, Caucasian origins, alcohol consumption, caffeinated drinks consumption, educational level, receiving social help and women taking contraceptives) for the age at first child among women. No association was found between Heaviness of Smoking Index and the number of children among current smokers in both genders. Women who smoke had their menopause more than 1 year prior than never-smoking women (48.9±0.2 years compared with 47.8±0.3 years, respectively, p=0.002).
Conclusions Smoking is associated with an earlier age of having the first child and of menopause among women.
- PREVENTIVE MEDICINE
- REPRODUCTIVE MEDICINE
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Contributors J-BO wrote most of the article. PM-V helped in the statistical analysis and in the writing of the article. PM-V, FB, PV and GW collected data and wrote part of the article. PM-V had full access to the data and is the guarantor of the study.
Funding The CoLaus study was and is supported by research grants from GlaxoSmithKline, the Faculty of Biology and Medicine of Lausanne, and the Swiss National Science Foundation (grant numbers 33CSCO-122661, 33CS30-139468 and 33CS30-148401).
Disclaimer None of the funders had any role in the study design, the analysis or interpretation of the data, in the writing or in the decision to submit the manuscript.
Competing interests None declared.
Ethics approval The CoLaus study has been approved by the Institutional Ethics Committee of the University of Lausanne.
Provenance and peer review Not commissioned; externally peer reviewed.
Data sharing statement No additional data are available.
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