Certain reproductive factors in women may reduce their risk of early death, according to research published in BMC Medicine.
Reproductive events represent significant biological milestones in a woman’s life and are associated with profound physiologic and endocrinological changes.
Previous studies have examined individual reproductive factors and the associated risk of all causes of death and disease-specific deaths, but they have not yet been drawn together to understand how they may influence the general long-term health of women.
However, as these factors are closely linked, researchers have now looked at several reproductive characteristics together in relation to risk of all-cause death, as well as death from cancer and cardiovascular disease.
The team, led by Melissa Merritt from Imperial College London in the UK, analyzed data from 322,972 women from 10 countries that participated in the observational European Prospective Investigation into Cancer and Nutrition (EPIC) cohort study.
Participants started by completing questionnaires and interviews about diet, lifestyle characteristics and medical history to capture baseline characteristics.
Each woman was followed for an average of 12.9 years, during which time there were 14,383 deaths overall, including 5,938 deaths from cancer and 2,404 deaths from circulatory system diseases.
Overall, it was found that women who gave birth, especially between the ages 26-30, those who breastfed, those who started menstruating after age 14 and those who had taken oral contraceptives were more likely to be in good health and less likely to develop cancer or cardiovascular disease.
There was a lower risk of death overall for women who gave birth between the ages 26-30; the risk was higher for those who gave birth early, aged 20 years or less or aged 31 years or more.
A reduced risk of death in women who had breastfed was also found compared with those who did not.
Women who started menstruating at age 15 or older had a lower risk of death compared with those who started before the age of 12.
A reduced risk of death overall was also seen in women who had ever taken oral contraceptives, provided they had never smoked or were former smokers.
The risk of cancer was lower for women who had given birth, compared with those who had not. Moreover, women who had two or three children had a lower risk of cancer than those who only had one.
- Heart disease is the number one risk, causing 22.5% of female deaths
- Cancer is number two, responsible for 21.5% of deaths
- The most deadly cancer for US women is lung cancer, followed by breast cancer.
There was also a lower risk of cancer in women who had ever taken oral contraceptives and who were never or former smokers.
A reduced risk of cardiovascular disease was associated with: having given birth, breastfeeding and starting menstruation at age of 15 or older, compared with those who started when they were less than 12 years old.
Further analysis found that women who gave birth and breastfed also had a reduced risk of death from ischemic heart disease.
The reproductive factors involved are all associated with changes in hormonal levels, suggesting that hormonal mechanisms may be behind the reduced risk of death.
The observational nature of this study means that it is not certain that the factors cause the decrease in risk.
Further studies are needed to confirm the findings and clarify the mechanisms that link these risks, which could then help to develop new strategies to improve health care.
“We observed, after controlling for other factors known to influence risk of death – such as body mass index [BMI], smoking habits and physical activity levels – that several reproductive factors were associated with a significantly lower risk of death. Many of these associations were also apparent when we considered cause-specific deaths from total cancer and ischemic heart disease. These common reproductive factors may influence the long-term health of women.”
A better understanding of how these factors can influence long-term health could help in the development of clinical strategies to improve women’s health.
Earlier this year, Medical News Today reported that hormonal factors reduce the risk of endometrial cancer.