It’s a multifaceted condition that can affect women differently but symptoms tend to begin in late adolescence. These can include irregular or no periods, irregular ovulation, extra facial or body hair, acne, weight gain and hair loss from the head.

“At different stages of your life you present in different ways,” says Prof Colin Duncan of the MRC Centre for Reproductive Health at the University of Edinburgh in Scotland.

The original name derived from a common feature of the condition – polycystic ovaries. But the moniker is misleading. “It implies there are cysts in the ovaries,” Duncan says. But that’s not the case.

He says the erroneous name probably arose when researchers first looked at the ovaries of people with the condition and saw multiple small fluid-filled sacs.

These sacs are not cysts, they are follicles – structures that contain an egg.

In healthy women, multiple follicles start to develop within an ovary each month, a process that eventually leads to one reaching maturity and releasing an egg, while the others wither away.

In women with PMOS the development of some follicles becomes paused, and often a follicle does not mature to release an egg.

What causes PCOS/PMOS?

The development of polycystic ovaries is associated with another common hallmark of the condition: an overproduction of androgens by the ovaries.

These “male sex hormones” are produced in all women but people with PMOS often have an excess.

This overproduction is usually caused by an imbalance between two other hormones: follicle-stimulating hormone and luteinising hormone. Research is ongoing into why exactly that hormone imbalance occurs.

Other factors also make the overproduction of androgens worse. Many people with PMOS are more resistant to the hormone insulin, meaning the body produces higher levels of this hormone in an effort to compensate. Crucially, high levels of insulin also increase the production of androgens.

“Increased androgens will also make you more insulin resistant,” Duncan says. “And insulin-resistance makes you produce more androgens. So there is this vicious cycle.” 

Excess body weight can also amplify the situation. Not only is this linked to insulin resistance but it can also lead a drop in the levels of a protein that mops up excess androgens. PMOS itself can increase the risk of weight gain.

PMOS can run in families, suggesting genes play an important role. Researchers are trying to identify which genes are involved.

“Because it’s a complex hormonal disorder, it’s not surprising that it’s not a single gene, but that many genes are involved,” says Stephen Franks, an emeritus professor of reproductive endocrinology at Imperial College London.

Research suggests there could also be other factors at play, for example, studies in animals have suggested greater exposure to androgens in the womb might increase the risk of offspring developing PMOS.

“I think probably it is a mixture of nature, nurture and prenatal programming,” Duncan says.

How is PCOS/PMOS diagnosed?

The condition is now diagnosed based on what is called the Rotterdam Consensus. In this framework, women must have two of the following three symptoms: biochemical or clinical manifestations of high levels of androgens – for example excess facial or body hair, or acne – irregular periods, and polycystic ovaries.

“It means you can have polycystic ovary syndrome without polycystic ovaries or you can have polycystic ovary syndrome without an irregular period,” Duncan says.

How common is it?

According to the World Health Organization, the condition affects an estimated 10% to 13% of women of reproductive age.

“Although it’s a lifelong condition, diagnostically it can only really be diagnosed in the reproductive years,” Duncan says.

Duncan adds the condition is more common in some countries than others. For example, it is more prevalent in south Asia and less prevalent in northern Europe. But the WHO notes that about 70% of women are thought to be unaware they have the condition.

What does it mean for women’s health?

“Polycystic ovary syndrome is a lifelong condition,” Duncan says. “And at different parts of your life, there are different things that become more important to you.” 

For example, irregular ovulation can make it difficult for some women to become pregnant, with the NHS that it is one of the most common causes of female infertility.

But PMOS is not just about women’s potential to have children.

“Sometimes people will come with irregular bleeding that sometimes can be prolonged, and that’s because of the lack of a normal cyclical hormone profile,” Duncan says.

The condition also increases the risk of high cholesterol and is associated with an increased risk of endometrial cancer.

What’s more, PMOS increases the risk of type 2 diabetes and high blood pressure and these factors contribute to higher risk of cardiovascular disease later in life.

In addition, it is associated with a greater risk of obesity – a condition that can exacerbate symptoms of PMOS and raise the risk of other disorders such as sleep apnoea.

“Women with polycystic ovary syndrome burn off less calories in response to eating than other people,” Duncan says. “So they find gaining weight easier and losing weight more challenging.” 

“We also know that because they see that their weight doesn’t respond the same way to diet and exercise [as] their friends, there’s a much higher incidence of eating disorders in [people with] polycystic ovary syndrome,” he says.

PMOS can also affect other areas of mental health, with women who have the condition at higher risk of depression and anxiety.

How can PCOS/PMOS be managed?

As Duncan points out, there is no cure and it’s a lifelong disorder.

“How you manage it depends on what the key issues are at the time,” he says, noting sometimes that will mean focusing on weight-loss strategies, while other times it might mean focusing on fertility or prevention of diabetes and cardiovascular disease.

Franks says hormonal contraceptives can be used to regulate periods and suppress levels of androgens to help reduce hair growth in women who have excess body hair, while drugs can be given to stimulate ovulation in women hoping to become pregnant.

The development of a new wave of weight-loss medications could also be beneficial, Franks says, and trials are ongoing.

Why is PCOS being renamed?

The main reason is that it is a misnomer. Not only can people have the condition without having polycystic ovaries, but the condition does not involve cysts.

There is another problem with the name PCOS: “It implies it’s all about the ovary, which it’s not,” Duncan says.

Franks agrees. “It’s a disorder in the ovary, but there are other manifestations which are equally if not more important in terms of metabolic abnormalities.” 

He says he was persuaded of the need for the name change after surveys carried out by Prof Helena Teede, an endocrinologist from Monash University, which revealed the majority of both health professionals and people with the condition felt a change was needed.

“I think it was time,” he says.

What is the new name for PCOS, and what does polyendocrine metabolic ovarian syndrome (PMOS) mean?

The name change to polyendocrine metabolic ovarian syndrome is the fruit of years of international effort and, it is hoped, will tackle the misleading aspects of the PCOS label.

In particular PMOS reflects the long-term, complex nature of the health condition, emphasising that it is a hormonal or “endocrine” disorder that can affect the body’s reproductive and metabolic systems and is associated with multiple health conditions.

• The Guardian