April showers bring May flowers, but that’s not all. Menopause also blossoms in the springtime, according to researchers in Hungary, suggesting there are seasonal variations in reproductive hormones that make it more likely for women to start missing periods in the spring months rather than the fall.
"The seasonality found in cessation of menstrual bleeding seems to support the influence of environmental factors on female human reproductive functions, even at their decline," wrote researchers from the Baranya County Teaching Hospital in Pécs, Hungary.
But they added that the triggering factors involved with the onset of menopause need to be further investigated. Their study was published in the current issue of the journal Human Reproduction.
Menopause is triggered by internal and external—or environmental factors. One such factor is the seasons. In wild animals, seasonal breeding and reproductive function is well-documented, but the data on civilized humans is lacking.
In this anonymous survey of 102 women in Pécs, Hungary whose average age was 52 years, a significantly greater proportion of the women remembered missing their first period—signaling the start of menopause—during the spring months. The numbers for spring were more than double that of the winter, fall, and summer months.
"Our sample shows a conspicuous seasonality in cessation of menstrual bleeding, with a higher peak after the vernal (spring) equinox and a lower one after the autumn equinox," wrote the researchers.
One suggestion by the researchers for the variation in seasonal reproductive function is the length of night and day, and the role of melatonin—a hormone that regulates the 24 hour body clock. Melatonin signals length of day to various processes in the body. It is secreted by the pituitary gland and present in the ovaries where it helps regulate production of some ovarian hormones.
The researchers suggest that in early peri-menopause a decrease in melatonin levels may set off a cycle where the capacity to provide an adequate hormone supply is decreased. Not only is length of day a factor, but also temperature and humidity in combination with other factors happening inside a woman’s body—such as lifetime supply of eggs. The researchers said that due to an imbalance of these factors in pre-menopause, the process eventually leads to a state where the ovaries can no longer recover their healthy function which results in ovarian failure—or menopause.
Again, the researchers stress that while there appears to be a correlation between the seasons and the onset of menopause, further study is needed to investigate the relationship.