Between the ages of 18 and 42, women’s body temperature at rest increases a little more each year. The reasons for this phenomenon are not yet completely clear to the scientific community, but according to the media New Scientist, this already makes it possible to consider measuring body temperature as a tool for analyzing women’s health, their approach to menopause or potential health problems.
“We believe that the temperature signal holds a lot of information about health”explains Marie Gombert-Labedens, researcher at the SRI International Institute, based in California. With her team, the latter analyzed data from a study dating from the 1990s in which 750 women measured their temperature every morning for around five years.
At the time, analysis of this data showed that on average, women’s body temperature was lower during the first half of the menstrual cycle and higher during the second half, after ovulation. Many fertility tracking apps now use this temperature variation to predict a user’s fertile window.
Marie Gombert-Labedens and her colleagues re-examined these data in more detail, to study the influence of age on body temperature during different phases of the menstrual cycle. They found that each year, from the ages of 18 to 42, the participants’ body temperature increased slightly. Women aged 35 and over then had a body temperature approximately 0.05°C higher than that of younger women. And this, during both phases of the menstrual cycle.
A new approach to health
The SRI International team’s analysis is consistent with their previous research, which showed that the skin temperature of the fingers, measured continuously by a connected ring, was on average higher in women aged 42 to 55 than in those aged 18 to 35. While further research is needed to explain this increase, the team of scientists believe it is probably linked to hormonal changes, particularly at the end of the fertile period.
Marie Gombert-Labedens specifies, however, that at the start of perimenopause, the temperature can rise suddenly and cause hot flashes and night sweats, but it is not known whether these are the same mechanisms that are at play. Also, the study only included women not using hormonal contraception and who did not suffer from hormonal disorders: scientists therefore do not yet know how these factors could affect body temperature over time.
The higher body temperature around forty could also explain why some women of this age say they are less sensitive to the cold than before, according to Marie Gombert-Labedens: “We hypothesize that this higher temperature in middle-aged women could influence their perception and reaction to ambient temperature.”
With the popularization of objects measuring temperature, such as smart rings, it may be possible in the near future to identify trends or variations in the body temperature of individuals, to estimate their rate of biological aging or to detect early signs of ovarian cancer or other conditions. Marie Gombert-Labedens is optimistic: “We hope this will facilitate research to identify new disease markers: it could be an untapped source of information about our health.”
