Menopause possibly affected by seasons

They say there's a season for everything, and that may even be true for menopause.

In a small survey from Hungary, women were most likely to stop having their period soon after the spring and fall equinoxes.

There was a peak after the spring equinox and a smaller one after the autumn equinox, according to a team led by Dr. Janos Garai at the University of Pecs.

The findings suggest that factors other than the dwindling of a woman's egg supply influence when she enters menopause, the researchers note in the journal Human Reproduction.

Although the findings are interesting, Garos told Reuters Health, "We still lack essential scientific knowledge on several aspects of the menopausal transition." He noted that the study looked only at when women first stopped menstruating.

"Although this is an essential step in the process of the transition between premenopausal and postmenopausal life stages, at the moment we perceive the boundaries of the 'perimenopausal period' as rather uncertain and not sharp or discrete at all," Garai said.

In the study, 102 women answered anonymous questionnaires about when they started menopause. Seventy-two women recalled the exact month, while the remaining women remembered the season when they first stopped menstruating.

Spring was the most common season for women to enter menopause, with autumn running a distant second.

No one disputes that the decline in a woman's egg supply plays an important role in determining the beginning of menopause. But the findings suggest that other factors, both within the body and outside of it, may also play a role, according to the researchers.

For instance, length of day, temperature and humidity, which vary from season to season, could influence the start of menopause, the authors suggest.

Garai's team notes that seasonal variations in breeding are well known among non-human mammals, and ovarian activity in some monkeys has been shown to be affected by seasons.

According to the researchers, the hormone melatonin may help explain some of the seasonal variations of menopause.

Melatonin promotes sleep and helps regulate the body clock. It is also known to influence a woman's menstrual cycle. Melatonin production is affected by the length of day, which varies with the seasons.

The next step, according to Garai, is to follow a group of women as they begin menopause. In that study, researchers will record when women stop menstruating when it first happens rather than relying on women's memories, Garai explained. The Hungarian researcher expects that the new study will confirm the results of the initial study.

Besides the onset of menopause, it is possible that symptoms of menopause, such as hot flashes, may be affected by the seasons, according to the Hungarian researcher. Some but not all women experience hot flashes during menopause, and Garai noted that no one has studied whether the season when menopause starts is related to the severity or frequency of hot flashes.