New findings offer fertility hope for women with PCOS

Published on 19 December 2025

NUH and NUS Medicine studies suggest many Singapore women with polycystic ovary syndrome (PCOS) have a milder subtype and better IVF odds, even at older ages.

At a glance

• A ground-breaking study published in Nature Medicine fundamentally changes the narrative on PCOS after 90 years.
• PCOS has four subtypes, and the milder SHBG subtype is the most common in Singapore.
• NUH IVF data (1,249 Asian women, 2016–2022) found women with PCOS had higher pregnancy rates, including among women aged 36 years and above.
• Researchers link the stronger outcomes to ovarian reserve, with many PCOS patients retaining egg numbers for longer.

For years, PCOS has been framed as a condition that complicates pregnancy. New local data suggests that for many women here, a PCOS diagnosis may not carry the poor fertility prognosis it is often assumed to.

When Ms Andrea Lee (not her real name), 40, first sought help for irregular periods in her early 30s, she was told she did not have PCOS. “Doctors said I had a lot of eggs,” she recalled. "But because I didn’t have some of the more typical signs, such as excess hair growth or obesity, it wasn’t suspected at the time.”

A few years later, during fertility treatment at the National University Hospital (NUH), she was diagnosed with PCOS. Friends warned her it would be a difficult journey. “But I responded well at each stage,” she said. She later gave birth to her child, now two years old.

For Ms Ke Youduan, 48, the discovery came by chance. She joined an NUH study on PCOS, assuming she was in the control group of women who did not have PCOS. A blood test revealed otherwise.

“I had no clue as there were no signs,” she said. “I actually have four children, all conceived naturally.” 

Their experiences may be more common than many expect. Among Singapore’s validation cohort of 127 women diagnosed with PCOS, 53 per cent fell into the SHBG-PCOS subtype — the group associated with the mildest profile and the most favourable reproductive outcomes.

A more nuanced picture of PCOS

PCOS is a hormonal disorder that affects ovulation, metabolism and, for some women, appearance. It has long been associated with elevated testosterone, weight gain and irregular menstrual cycles. But emerging data show that the condition presents differently across populations.

A study published in Nature Medicine in October 2025 examined women from China, Singapore, Brazil, Europe and the United States. It identified four subtypes of PCOS. Three matched the familiar profile: raised testosterone (hyper-androgenic PCOS), higher body weight (overweight-obesity PCOS), and elevated levels of luteinising hormone (LH) and anti-Müllerian hormone (AMH), both indicators of ovarian function.

The fourth subtype — marked by high levels of sex hormone-binding globulin (SHBG) and lower testosterone — shows few outward signs. Women in this group generally have lower body weight and do not experience excess hair growth. And this is the subtype to which most Singaporean women with PCOS belong.

“Much of what we know about PCOS comes from studies in Western populations,” said Prof Yong Eu Leong from the Department of Obstetrics and Gynaecology at the Yong Loo Lin School of Medicine, National University of Singapore (NUS Medicine), and NUH, a corresponding author of the study.

“Our new study plugs this gap by demonstrating that PCOS is not a single condition but comprises diverse subtypes. We now know that the majority of Singaporean women with PCOS are of the subtype associated with the most favourable outcomes.”

The study found women in this subtype were more likely to return to regular menstrual cycles, and had lower rates of diabetes, hypertension and high cholesterol than the other groups.

What this means for fertility

A second study led by Adj Asst Prof Huang Zhongwei, from the Department of Obstetrics and Gynaecology at NUS Medicine and NUH, examined in-vitro fertilisation (IVF) outcomes in 1,249 Asian women aged 22 to 42 years who underwent treatment at NUH between 2016 and 2022.

Women with PCOS consistently achieved higher pregnancy rates. Among women aged 36 years and above, pregnancy rates were 70 per cent in those with PCOS, compared with 27.6 per cent in women without.

The key factor appears to be ovarian reserve — essentially, how many eggs a woman still has. Women with PCOS, especially those in the SHBG subtype, tended to keep more eggs for longer. During IVF, they also produced nearly twice as many eggs per treatment cycle as women without PCOS, giving them more opportunities over the course of treatment.

“That was what surprised me most about the study,” said Adj Asst Prof Huang, who is also Deputy Director of the Bia-Echo Asia Centre for Reproductive Longevity and Equality (ACRLE) at NUS Medicine. “We had always expected women of an older age to have lower chances of pregnancy. But with these results, I have had to change my stance when I counsel my patients.”

Prof Mahesh Choolani, Head of the Department of Obstetrics and Gynaecology at NUS Medicine and NUH, and a co-author of the study, said the work reinforces the need for personalised fertility counselling and timely access to fertility treatments.

“Recognising that PCOS comprises distinct subtypes allows us to care for women in a more personalised way,” he said.

“Our focus is to translate these insights into clear guidance and tailored care, so women can plan their families with confidence while safeguarding their long-term health.”

In consultation with Prof Mahesh Choolani, Prof Yong Eu Leong and Adj Asst Prof Huang Zhongwei, Department of Obstetrics and Gynaecology, NUS Medicine and NUH.