Scientists have discovered a link between polycystic ovary syndrome (PCOS) and a hormonal imbalance before birth. In a new study, researchers at the French National Institute of Health and Medical Research suggest PCOS could be caused by overexposure to a hormone called anti-Müllerian (AMH) in the womb and were able to reverse the syndrome in mice.
Polycystic ovary syndrome affects up to one in ten women of reproductive age worldwide. Around 75% of women with the condition struggle to conceive, making PCOS the leading cause of female infertility. Women with PCOS experience symptoms including irregular menstruation, lack of ovulation, cysts on the ovaries and excess hair growth on the face and body. Women who have the condition are also at a higher risk of developing metabolic problems including type 2 diabetes. Although the syndrome is known to run in families, the cause is not understood.
“It’s by far the most common hormonal condition affecting women of reproductive age but it hasn’t received a lot of attention,” Robert Norman, a professor of reproductive medicine at the University of Adelaide in Australia who was not involved in the research, told New Scientist.
Led by Paolo Giacobini at the French National Institute of Health and Medical Research, the team measured levels of AMH in a cohort of pregnant women with PCOS and a group of pregnant women without the syndrome.
Their results, published on Monday in the journal Nature Medicine, showed that levels of AMH were 30% higher in pregnant women with PCOS than those in the control group.
To determine whether this hormonal imbalance could play a role in the foetus’s development of PCOS, the team injected pregnant mice with high levels of AMH. They found that female offspring experienced irregular menstruation, late puberty and fertility issues – symptoms similar to those found in women with PCOS.
Researchers believe the high levels of AMH over-stimulated brain cells to produce excess testosterone, which then crossed the placenta and affected the foetus. The team was able to reverse the induced PCOS symptoms in the mice using an in vitro fertilisation (IVF) drug called cetrorelix.
“It [the drug] could be an attractive strategy to restore ovulation and eventually increase the pregnancy rate in these women,” Giacobini told New Scientist.
Giacobini and his team hope to conduct a cetrorelix trial on women with PCOS by the end of the year. Current fertility treatments for women with PCOS typically have success rates below 30% across five menstrual cycles.
“The findings are nothing short of astonishing,” Megan M. Stewart, the founder of the PCOS Awareness Association, told Newsweek. Stewart said the association’s followers had shown “a great deal of hope and excitement that future generations will not have to suffer the way 10 million women with PCOS suffer today.”
“It’s a radical new way of thinking about polycystic ovary syndrome and opens up a whole range of opportunities for further investigation,” added Norman.
Other PCOS researchers not involved in the study said the new work was strong, but had some reservations about the findings’ implications for humans.
“Whether all these things happen in humans, we don’t know,” Jeffrey Chang, a reproductive endocrinologist at the University of California, San Diego, told Science Magazine.
Jerome Strauss, a reproductive endocrinologist at the Virginia Commonwealth University in Richmond in the United States also mentioned the difficulties of applying the findings to humans, telling Science the model’s “transportability to human biology is very difficult.”