Menopause May Be Tied to the Seasons
Study: Start of Menopause Peaks in Spring Months
June 9, 2004 -- Mother Nature may play a much larger role in
determining when a woman ends the reproductive phase of her life than
previously thought. A new study suggests that the start of menopause may be
linked to seasonal weather patterns.
Researchers found the number of women reporting their first
missed period peaked in the spring months and in the autumn months to a lesser
degree. The study appears in the current issue of Human
Researchers say seasonal variations in the reproductive
functions of wild animals are well known, but this is among the first studies
to look at their possible effect on humans.
"The seasonality we found seems to
support the influence of environmental factors on female human reproductive
functions even when they are declining," says researcher JÃ¡nos Garai, of
the University of PÃ©cs in Hungary, in a news release.
Change of Life Linked to Seasonal Changes
In the study, researchers surveyed 102 women who were treated
at a menopause clinic in Hungary and asked them about the month of their first
missed period. Seventy-two of the women remembered the exact month their
menopause process started, and 30 could remember only the season.
Researchers say the results revealed seasonal variation in the
start of menopause, with a peak after the vernal (spring) equinox and a smaller
peak after the autumnal equinox. The fewest number of women reported starting
menopause in the summer and winter months.
Researchers say more study is needed to
understand this relationship between the seasons and the start of menopause.
But they suggest that melatonin, a hormone that plays a role in the circadian
rhythm or 24-hour body clock, could be involved in the process.
They say melatonin is generally accepted as
a signal that transmits length of day information to different processes in the
body. In addition, melatonin influences ovarian hormone production. Previous
research has suggested that the link between these hormones becomes disrupted
as melatonin levels decline in perimenopause.
"Because of the imbalance of these
factors in pre-menopause, the process eventually culminates in a point where it
stumbles into irrecoverable ovarian failure," says Garai. "Length of
day is likely to be only one of several factors operating and melatonin might
not be the only agent involved, so we need to research this