Study Links Gradual Body Temperature Rise to Perimenopause Prediction

Women’s body temperature subtly rises from their late teens to their early forties, and the changes could be tracked to predict the approach of perimenopause before noticeable symptoms appear, researchers say. A study published in the journal Science Advances analysed more than 5,600 menstrual cycles in 753 women aged 18 to 42.

It found that as women got older, several features of their monthly body temperature pattern changed. On average body temperatures were slightly higher in the older women, and cycles became shorter with age. 004C per year on average. The paper describes how a “subtle but significant” rise was recorded when the lowest five daily temperature values of each cycle were tracked.

” The research looked at basal body temperature, the body’s resting temperature, usually taken early in the morning before getting out of bed. It is already used by some fertility and period-tracking apps because it tends to rise after ovulation. According to Gombert-Labedens, it appears that each woman may have her own monthly temperature “footprint”.

If that personal pattern begins to shift, it could provide an early clue that reproductive ageing, including perimenopause, is under way. “These temperature changes may result from perimenopause, overall ageing, or a combination of both. If perimenopause does play a role in these changes, there are good chances that, in turn, temperature could help predict perimenopause,” she said.

However, she and her team stressed that more work was needed to test the link.

During midlife women may experience several changes that affect how their bodies control temperature. Some of this may be linked to perimenopause, when hormone levels begin to change as the ovaries have fewer eggs left. Hormones such as progesterone and oestrogen help to regulate body temperature.

Some of the changes may be linked to ageing more generally. As people get older the systems that control body temperature can change, including how the brain senses heat and cold. A woman may have about 450 menstrual cycles in her lifetime. However, Gombert-Labedens said that the vast majority of research and medical attention had focused on the small number of cycles linked to pregnancy.

She and her colleagues believe this misses a bigger opportunity. Menstrual cycles are not just about fertility, she said: they are regular biological rhythms that could be “an untapped window into women’s health”.