Public Release: 

Young teen smokers may run heightened risk of chronic severe period pain

Starting smoking by age of 13 may have greatest impact

BMJ

Most women will experience period pain (dysmenorrhoea) during their reproductive life, with the pain severe in up to 29%.

Smoking has been mooted as a potential risk factor, but the research to date has been inconclusive.

The study authors studied a large population sample of 9000 women, all of whom were taking part in the Australian Longitudinal Study on Women's Health, from 1996 onwards.

Every 3-4 years between 2000 and 2012, the women were asked about the frequency of severe period pain they had experienced, and whether they currently or had ever smoked. Current and ex-smokers were asked at what age they started.

Information was also collected on other key influential factors, such as educational attainment, marital status, employment, residential area, weight, lifestyle and reproductive history.

In 2000, when the women were aged between 22 and 27, over half (59%) were non-smokers and around one in four (26%) were current smokers.

Around 7% of the women had started smoking by the age of 13, with a further 14% starting their habit at the age of 14-15. And 8% said they had started smoking before they began having monthly periods.

In 2000, one in four women said they regularly experienced period pain every month. The prevalence of period pain was slightly higher in current smokers (29%) than in non-smokers (23%).

The women were divided into four groups according to the type and duration of period pain they had.

The 'normative' group comprised 42% of the total sample, defined by no or few symptoms throughout the monitoring period; 11% of the women were categorised as 'late onset,' defined by an increasing prevalence of period pain from 15% to nearly 70%.

The 'recovering' group comprised 33% of the women, defined by a decreasing prevalence of period pain from 40% at the age of 22-27, to 10% by the age of 34-39.

Some 14% of the women were categorised as the 'chronic' group, defined as a high prevalence of period pain of between 70% and 80% throughout the monitoring period.

Compared with women who had never smoked, current smokers who had started smoking by the age of 13 were more likely to be in the chronic group, as were women who were unemployed, had started their periods early, who were obese, and who spoke a European language at home.

After taking account of influential factors, current smokers who had started smoking by the age of 13, were 60% more likely to fall into the chronic group than non-smokers.

This is an observational study so no definitive conclusions can be drawn about cause and effect, but there are possible explanations for the association, say the authors.

Cigarette smoking is known to constrict arterial blood flow, which could potentially cause pain. Alternatively, it might have a direct effect on the hormones involved in menstruation, which may be particularly important before the onset of puberty and regular monthly periods, say the authors.

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