Women who begin menstruating before age 10 or after age 17 may have a higher risk of heart disease, according to a new study.
Menarche tends to occur earlier in obese children, so the link between earlier periods and later heart disease risk was expected, said lead author Dr. Dexter Canoy of the University of Oxford in the U.K.
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But his team was surprised to find another increase in risk for older age at menarche, he told Reuters Health by email.
"Menarche, onset of first full menstrual cycle, is a marker of puberty and the onset of endocrine functions relating to reproduction, but why the timing of menarche is associated with increased vascular disease risk remains unclear," Canoy said.
Researchers studied health data for more than one million U.K. women ages 50 to 64, including reproductive and medical history and national data on deaths and hospitalisations over the subsequent decade.
Over the course of about 11 years, almost 250 000 women were hospitalised for or died from complications of high blood pressure, 73 000 developed heart disease and more than 25 000 had suffered a stroke.
Lowest risk of heart problems
Those who had their first period at age 13, about 25 percent of the group, had the lowest risk of heart problems during the study.
Compared to those women, the four percent who reported having their first period at age 10 or younger were about 27 percent more likely to develop heart disease.
Heart disease risk increased almost as much for the one percent of women who started menstruating at age 17 or older, according to data in the journal Circulation.
Stroke and high blood pressure patterns were similar, but the increases in risk were smaller than for heart disease, the authors write.
"This is a very interesting paper confirming previous association studies showing links between early menarche and cardiovascular disease risk," said David Dunger, a paediatric clinical scientist at the University of Cambridge in the U.K. who was not involved in the new study.
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But previous studies have not included such a large group of women, he told Reuters Health by email.
The risks remained even when the authors accounted for body size, smoking and socioeconomic status, Canoy said.
Applicable to middle-aged Caucasian women
These findings are likely applicable to middle-aged Caucasian women born between 1930 and 1950 in industrialised countries, Canoy said. The women in the current study were mostly white.
Researchers need to see whether the findings are similar in women of different ethnicities or from less industrialized countries, he added.
Heart disease risk was slightly different for women whose first period came at age 12 compared to those who started at age 15, but so small as to likely be clinically unimportant, he said.
"Strategies to prevent excess weight gain during childhood may also avoid menarche occurring at an earlier age than necessary, which in turn could reduce the risk of developing heart disease and stroke in the long-term," Canoy said.
Average age at menarche has been on the decline since the late 1800s, Canoy noted.
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"What is currently unexplained is whether the timing of menarche per se is somehow what is crucial or is there another factor occurring/operating at around middle-age (which might happen to be a correlate of age at menarche) that increases susceptibility to the development of heart disease," Canoy said.
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