women get – A long-term analysis of daily body-temperature readings finds that women, on average, get progressively warmer from age 18 to 42—an unexpected shift that may someday help track ageing, flag perimenopause, and even spot potential health problems.
On some mornings, the difference is tiny—so small it barely registers until you stack years of measurements together. In a large dataset of women taking their temperature every day. researchers found a steady rise in resting body temperature from the start of adulthood into midlife. The effect is subtle, but it’s consistent: from age 18 to 42, women become a fraction warmer each year.
The project was led by Marie Gombert-Labedens at SRI International, a research institute headquartered in California. She and her colleagues say the temperature signal may contain “a lot of information about health.” Their goal is to see whether daily body temperature—captured by wearables in the future—could become a marker for conditions that currently go undetected or are difficult to time precisely.
The team re-examined data from a study in the 1990s that involved more than 750 women aged 18 to 42. Each participant measured oral or rectal temperature with a thermometer every day when they first woke up. When the researchers looked at the menstrual-cycle timing. the pattern was familiar: body temperature was lower during the first half of the cycle and higher during the second half after ovulation. Fertility-tracking apps often use that temperature jump to predict a person’s fertile window.
But Gombert-Labedens and colleagues went further, breaking down how age changed temperature across different menstrual stages. They found that, on average, each year from 18 to 42 came with a fraction more warmth. By the time participants were 35 and older. their readings tracked about 0.05°C hotter than those of younger women across both halves of the menstrual cycle.
The finding lines up with earlier work from the same group: finger skin temperature measured continuously by a smart ring was warmer on average in women aged 42 to 55 than in those aged 18 to 35.
What drives the rise remains unresolved. Gombert-Labedens suggests hormonal changes may be involved, especially toward the end of the reproductive years. When perimenopause begins. temperature can increase suddenly and cause hot flushes and night sweats—but whether that dramatic symptom is tied to the same underlying mechanisms as this gradual midlife warming is still unclear.
There’s also a gap in what researchers can safely conclude from this dataset. The study included only women who did not use hormonal contraception and did not have hormonal conditions such as PMOS (polyendocrine metabolic ovarian syndrome. previously known as PCOS). That means the team doesn’t yet know how contraception or conditions like PMOS might affect how body temperature changes over time.
Other research points in a different direction later in life. After menopause, body temperature tends to drop back down to a lower level and become similar to that of men. Put together. the new results suggest that the midlife shift may be its own stage—one that doesn’t necessarily persist beyond menopause in the same way.
For many women, the body’s changing temperature isn’t just a lab measurement. Gombert-Labedens says the higher temperature around midlife could help explain an anecdote some women share: that they don’t feel the cold as much as they used to. She added that the team speculates midlife warmth could influence perception and reaction to environmental temperature.
The study also raises the possibility that temperature patterns—if tracked continuously—could become a practical window into what’s happening in the body. As smart rings and other temperature-sensing wearables become more popular. Gombert-Labedens says it may be possible to identify patterns or deviations in individuals’ temperature trends. Such signals could help detect the approach of menopause. estimate a person’s rate of biological ageing. or flag early signs of ovarian cancer or other conditions.
For now, the mystery sits in the space between what’s measurable and what’s understood: women appear to run warmer from age 18 to 42, the reasons are “still being figured out,” and the next step is figuring out which biological pathways create that gradual climb.
women body temperature menstrual cycle age 18 to 42 perimenopause hot flushes night sweats wearables smart ring ovarian cancer biological ageing
So like… hot girl summer starts early?
My wife says her body runs warm all the time, but this sounds like just normal aging? Like tiny differences add up or whatever. Also, why are they using rectal temps??
Wait is this saying women get warmer because of perimenopause like automatically? I’m 39 and my wearables always say I’m “higher” but I thought that was stress/sleep. They should’ve compared to men too, because my brother runs like a furnace and he’s 42. Idk, seems like a stretch but maybe it helps track stuff.
Interesting but also sounds like science trying to sell wearables lol. If it’s “0.05°C hotter” that’s basically nothing, so how would it “spot potential health problems” unless you already know what to look for. Also daily morning temps are super affected by room temp/blankets so I don’t buy the “steady rise” part fully. Still, perimenopause timing being predictable would be kinda useful I guess.