
A range of reproductive factors including the age when menstruation first starts and an early menopause are all linked to a heightened risk of COPD in women.
According to research published online in the journal Thorax, miscarriage, stillbirth, infertility and having three or more children are also associated with a heightened risk of COPD — including emphysema and chronic bronchitis.
The researchers noted that women seem to develop severe COPD at younger ages than men, and although smoking is a major risk factor, non-smokers with COPD are more likely to be women.
The study reported that previously published studies looking into the influence of female hormones on COPD risk have been hampered by methodological flaws. To get around this, researchers drew from the International Collaboration for a Life Course Approach to Reproductive Health and Chronic Disease Events (InterLACE) consortium.
The consortium is a collection of 27 observational studies bringing together individual data from more than 850,000 women in 12 countries. Data on three groups of women with an average age of 54 were selected from studies in Australia, the UK and Sweden.
The womens' health was monitored for an average of 11 years, during which time about 4% of the women developed COPD at an average age of 63.
A U-shaped pattern emerged for the age at which periods first started among the women studied. Those who began menstruating before or at the age of 11 were 17% more likely to develop COPD than those who began at the age of 13. After the age of 16, the risk was 24% higher.
Women with children were at a higher risk than those without. Women having three or more children had a 34% higher risk of COPD than those with two children, while women with one child were at an 18% higher risk. Women who experienced infertility had a 13% higher risk than women who were fertile.
A history of miscarriage was associated with a 15% higher risk of COPD, with the risk rising in tandem with the number of miscarriages. Similarly, stillbirth was associated with a 42% overall higher risk, with the risk rising along with the number of stillbirths.
Additionally, women who hit menopause before the age of 40 were associated with a 69% higher risk compared with those experiencing it naturally at the age of 50-51. The risk was 21% lower for those who went through it at the age of 54.