Number of eggs a woman has predicts heart attack risk

What Else An Eggs Can Say?

The number of eggs in a woman's ovaries could tell a lot more than just how fertile she is. It may provide a window onto how fast her cells are ageing and, in particular, reflect her risk of developing heart disease.

Number of Eggs and Disease Risks

Women are born with all of their eggs and, throughout their life, the number they have declines. The onset of menopause is triggered by this decline.

After menopause hits, the risk of heart disease increases. Women who experience it early – before the age of 46 – are at twice the risk of developing heart disease in later life as women who go through menopause at a typical age.

Several factors that coincide with menopause compound this risk, including a shift in the type of cholesterol the body produces, the redistribution of body fat and increased blood pressure. The drop in oestrogen levels is also thought to play a role as the hormone helps keeps blood vessels elastic. ButMarcelle Cedars at the University of California, San Francisco, wondered if the increased risk to women who experience early menopause might have a more fundamental cause. "Perhaps women who go through menopause early are intrinsically aging at a different rate," says Cedars.

Telling telomeres

To find out, Cedars' team took blood samples from 1100 non-menopausal women aged 25 to 45 and measured their amount of anti-Müllerian hormone (AMH), an indicator of how many eggs are in the ovaries. They confirmed the number of eggs by counting the pockets of fluid, called follicles, around each egg using an ultrasound.

To measure the women's biological age, the researchers looked at the length of telomeres in their white blood cells. Telomeres are the dangly bits at the end of chromosomes that shorten every time a cell divides. Their length is considered a measure of cellular age.

Between three and five years later, 250 of the women came back so researchers could calculate their risk of developing heart disease in the next decade – known as their Framington score. This takes account of risk factors such as cholesterol levels, blood pressure and body weight.

As expected, the team found that women with lower egg counts had higher Framington scores, but they also had shorter telomeres. Previous studies have suggested that shorter telomeres are linked with heart disease,dementia and cancer, and also with a shorter lifespan. So women with fewer eggs may also be at higher risk of other age-related diseases, although epidemiological studies will be needed to bolster this link.

Early warning

"We think the ovary may be more sensitive to the processes of aging," says Cedars, making it like a canary in a coal mine for a general state of accelerated aging.

"It is a very promising hypothesis that reproductive ageing could serve as a window into cardiovascular health and the cellular aging process," says JoAnn Manson, an epidemiologist at Harvard School of Public Health in Boston, Massachusetts.

Confirming that number of eggs, as well as age at menopause, is associated with risk of cardiovascular disease is important because heart disease is thenumber one cause of death for women around the world. Women are often diagnosed later than men and also tend to have a worse prognosis after being diagnosed, so finding ways to identify those at higher risk is crucial, says Cedars. Many women undergo AMH testing for fertility purposes and those with low egg counts could be monitored for cardiovascular health and advised to make lifestyle changes at a relatively young age, she says.

The researchers presented their findings this week at the annual meeting of the American Society for Reproductive Medicine in Honolulu, Hawaii.