Underweight women may be susceptible to early menopause
People who are underweight in their younger years may be more prone to going through the menopause early, a new study has revealed.
According to researchers, those women who were underweight at the start of the study were 30 per cent more likely to have experienced early menopause.
For women who had been underweight at age 18, their chances of early menopause were 50% greater than women who had been a normal weight aged 18.
Women who had a BMI under 18.5 aged 35 had a 59% increased risk of early menopause.
Conversely, early menopause wasn’t as likely for overweight women as it was for those who were normal weight.
In fact, it was 21% less likely for those with a BMI of 25-27.4 and 30% less likely for those with a BMI of 27.5-29.9.
The study, published in the journal Human Reproduction, looked at data from 78,759 women, mostly in their mid-30s, all of whom were pre-menopausal when the research began, and spanned a period of 22 years.
Researchers recorded BMI, weight distribution, weight changes, and age of menopause, as well as medical history, smoking, and exercise.
During that time, 2,804 women reached menopause before they were 45, which is considered early.
All of these women reached menopause naturally, and none because of a hysterectomy, radiation therapy, or for any other reason which could have explained their early menopause.
According to researchers, the mechanisms underlying the associations between low body weight and early menopause are unclear.
Low body weight does increase risk of amenorrhea, which can involve anovulation, hypo-oestrogenism and increased risk of infertility.
When someone has fewer ovulatory cycles due to oral contraceptive use, this has generally been associated with later menopausal age, but it is possible that anovulation caused by low weight is differentially associated with rate of reproductive ageing.
Amenorrhea can also lead to an increase in levels of the stress hormone cortisol, and it is possible that chronic elevation of stress hormones can also increase early menopause risk.
However, the study didn’t differentiate between women with anorexia nervosa and women who were constitutionally thin, and some studies have found that amenorrhea and hormonal imbalances only occur among women with anorexia nervosa.
While overweight women enjoy some lower risk of early menopause, there was no lower risk in obese women with a BMI over 35.
Up to 10% of women experience early menopause, which is defined as the cessation of ovarian function before age 45. Generally, someone is deemed to have gone through the menopause when they have not had a period for at least a year.
Early menopause is associated with higher risk of cardiovascular disease, cognitive decline, osteoporosis, and premature mortality.
Genetics are the single biggest predictor of when you are likely to go through menopause, but lifestyle, reproductive and environmental factors also play a role.