By Karen Pallarito
THURSDAY, Sept. 15, 2016 (HealthDay News) -- Women who enter menopause early may be at greater risk for heart disease and premature death, a new analysis suggests.
To reach this conclusion, the Dutch researchers reviewed 32 studies involving more than 300,000 women. The investigators compared women who were younger than 45 at the start of menopause with those who were aged 45 and older when it began.
Overall, heart disease risk appeared to be 50 percent greater for the women who were under 45 when menopause began.
Early menopause also appeared to boost the risk of cardiovascular death and death from all causes. But, it showed no association with stroke risk, the study authors said.
However, the study only uncovered an association -- not a cause-and-effect connection -- between early menopause and heart and death risk.
The study findings were published Sept. 14 online in JAMA Cardiology.
"These findings suggest that women with early onset of menopause may be a group to target for proactive cardiovascular prevention strategies," said study author Dr. Taulant Muka, of Erasmus University Medical Center in Rotterdam, the Netherlands.
For women in early or premature menopause, that may mean hormone therapy, the researchers said.
But the advice is different for women who enter menopause before age 45, explained JoAnn Manson. She is co-director of the Connors Center for Women's Health and Gender Biology at Brigham & Women's Hospital in Boston.
Since these women have a higher risk of heart disease and osteoporosis, unless there is a "clear reason" to avoid it, experts recommend treatment with estrogen until at least the average age of natural menopause, Manson said.
Menopause typically begins at age 51. However, as many as one in 10 women experiences natural menopause by age 45, the study authors noted.
Also, certain cancer treatments or surgical removal of a woman's ovaries cause premature menopause.
One in three women worldwide dies from cardiovascular disease. And, for reasons not entirely clear, that risk accelerates in menopause.
Could the dramatic decline in levels of estrogen following menopause be to blame? It's probably more complicated than that, say the co-authors of an editorial that accompanied the study.
"We don't know definitively whether the reproductive system is influencing cardiovascular health or cardiovascular disease is influencing the ovary," said Teresa Woodruff, one of the editorial writers. She is vice chair for research in obstetrics and gynecology at Northwestern University in Chicago.
Manson, her co-author, said the link probably goes in both directions: early menopause boosts heart disease risk and risk factors such as high blood pressure (hypertension) and high cholesterol can damage the blood supply to the ovary and lead to early menopause.
Study author Muka, a postdoctoral researcher, offers a possible explanation for the heightened risk facing women with early menopause: Early loss of ovarian function may activate a system in the body that regulates blood pressure, body fluids and inflammation, he said.
"The inappropriate activation of this system causes hypertension and can damage your heart," Muka said.
It's also possible that there may be shared genetic or environmental risk factors that lead to early onset menopause and boost the risk of poor health outcomes, the researchers added.
Muka and his colleagues did pick observational studies for their analysis that evaluated women's age at onset as well as time since onset of menopause.
And only four studies assessed time since the onset of menopause in relation to cardiovascular risks, and the results were inconsistent.
However, the age-related findings showed a clear link, the investigators said. While early menopausal women faced increased heart and premature death risks, women aged 50 to 54 at the onset had a lower risk of fatal heart disease than women younger than 50.
Based on the findings, "age at menopause might be a predictor of future cardiovascular events and mortality in postmenopausal women," Muka said.
The findings were published online Sept. 14 in the journal JAMA Cardiology.
The study was sponsored and funded by Metagenics Inc., a California-based maker of nutritional supplements.