Women born in the spring may reach the menopause earlier than those born in the autumn, say scientists.
Women have been advised not to worry about the findings
A study of nearly 3,000 women found many of those born in March had hit the menopause aged 48, while the age for those born in October was often 50.
The Italian team said more work was needed to find out why this might be.
The findings, in Human Reproduction, held true even when factors that may affect menopause onset, such as weight and smoking, were taken into account.
"Mothers should be aware of this, considering that during pregnancy they are going to influence, not only the health of the newborn, but also the health and reproductive life of their child during adulthood," said Dr Angelo Cagnacci, from the University of Modena.
However, because the study looked only at women who had been referred to menopause clinics, the authors said their findings might not relate to all women and might differ country by country.
But they said it could be that environmental factors influence timing of menopause in the womb or even before conception.
For example, girls are born with all the eggs they will release each month in their later life when they begin to ovulate and have periods.
Survival of the fittest
It may be that women born in the autumn develop better as a foetus and are born with more eggs in their ovaries than women born in the spring, said Dr Cagnacci.
"An alternative explanation may be that early mortality is highest among children born in autumn, thus selecting the fittest for survival," he said, but also pointed out that other work did not support this view.
He said the seasonal trend might be caused by changes in sunlight and temperature or might be linked to changes in diet or infection rates.
Other researchers have shown that there is a similar seasonal variation in birth weight and human lifespan.
A survey of 100 women by experts from Baranya County Teaching Hospital in Pécs, Hungary, last year found menopause rates peaked in the spring and autumn.
They suggested the hormone melatonin, which plays a role in the body's internal daily clock, might be important.
Dr John Stevenson, a consultant at the Royal Brompton in London and spokesman for the British Menopause Society, said: "Women should not be worried about these findings.
"They are interesting for scientists, but really, they don't mean much for individual women. Plus, you can't alter when you were born."