This medication is good for mum, but her kids have a higher risk of developing allergies

PCOS is a hormonal disorder that affects about one in ten Norwegian women.

“Most women with PCOS are overweight, but the condition also affects women of normal weight,” says Eszter Ilona Vanky.

She is a senior consultant at St. Olav’s Hospital and professor at NTNU.

Concerned that more women are developing PCOS

Vanky wants to find out as much as possible about PCOS. She is now concerned about the increase in the syndrome.

She says that there are many more people who have troublesome symptoms with PCOS today than 25 years ago. 

"The reason is increased obesity in the population, but also more awareness of the condition. Obesity provokes PCOS in women who are predisposed to it. Severe obesity can in itself lead to PCOS even without prior predisposition,” says Vanky.

The medicine crosses the placenta

It's estimated that 70 per cent of women with PCOS have insulin resistance. This means that the body's cells respond less well to insulin, a hormone that lowers blood sugar.

Insulin resistance leads to overproduction of insulin. This in turn disrupts ovulation and stimulates the ovaries to produce more testosterone.

The diabetes drug metformin is therefore often recommended as a basic treatment for PCOS in women who are not pregnant. 

In addition to increasing sensitivity to insulin and thereby lowering insulin levels, metformin contributes to weight loss along with lifestyle measures, regulation of menstruation, and reduced male sex hormones.

A miracle drug?

It may almost sound as if metformin is a miracle drug for women with PCOS.

But one challenge during pregnancy is that the medication crosses the placenta and can thus affect the foetus directly.

No harmful effects on the foetus have been reported, but children who have been exposed to metformin in the womb appear to have:

• larger head circumference at birth
• increased vulnerability to developing obesity

Changes the immune system itself

The need for more knowledge about the long-term effects of metformin during pregnancy on the child has been highlighted in the international research community.

This is what researcher Mariell Ryssdal at NTNU has now explored.

She has just published an article showing how metformin during pregnancy affects immunological outcomes in mother and child. 

The study involved 634 women with PCOS who received either metformin or placebo throughout pregnancy. Of these, 292 mothers with children were invited to a follow-up study, 8 years after the pregnancy.

145 of the children participated.

“The study shows that metformin can affect the immune system of the foetus, so that the children more often develop eczema and allergies,” says Ryssdal.

Her research shows that when the children were around eight years old, they had twice the incidence of eczema, and almost fivefold the incidence of allergies.

So, if you only consider the child’s health with regard to allergies and eczema, it may not be such a good idea to take metformin during pregnancy, but unfortunately it is not that simple.

Fewer give birth prematurely

Women with PCOS also have a somewhat elevated risk of most types of pregnancy complications.

These include miscarriages, excessive weight gain during pregnancy, gestational diabetes, preeclampsia, premature birth, and stillbirth. 

The risk is reduced if the woman has a weight as close to normal as possible.

Metformin can be a good helper. The medicine leads to less weight gain during pregnancy. It also results in fewer premature births.

Vanky emphasises that the most important thing is to avoid premature birth.

“Being born far too early is a threat to the child’s health in the short and long term,” she says.

Children who are born very prematurely can, among other things, suffer lifelong brain damage and an increased risk of a number of chronic diseases.

Sometimes it's right to give this medicine

Vanky emphasises that metformin is by no means directly harmful to the foetus.

"We recommend women who are taking metformin and become pregnant to stop taking it within the first three months," she says. 

In some cases where the woman has an increased risk of very premature birth, treatment with metformin may be considered throughout the pregnancy.

“Sometimes metformin is the right thing to give, even for pregnant women, but it should be done individually. We do not recommend women with PCOS use metformin routinely throughout pregnancy,” says Vanky.

As with several women’s diseases, knowledge about PCOS in the healthcare system has varied.

Vanky is now working on an e-course for GPs under the auspices of the Norwegian Medical Association. The goal is for women with PCOS to receive equal treatment and be met with knowledge.

“Midwives and GPs should know more about PCOS. One of my fads is that it should be on the health card if you have this syndrome,” says Vanky.

Reference:

Ryssdal et al. Metformin Treatment in PCOS Pregnancies Reduces Maternal Infections and Increases the Risk of Allergies and Eczema in the Offspring: Post Hoc Analyses of Two Randomised Controlled Trials and One Follow-Up Study, BJOG, vol. 132, 2025. DOI: 10.1111/1471-0528.18320

———

Read the Norwegian version of this article on forskning.no

This content is paid for and presented by NTNU

This content is created by NTNU's communication staff, who use this platform to communicate science and share results from research with the public. NTNU is one of more than 80 owners of ScienceNorway.no. Read more here.

More content from NTNU:

• 

  Here's the first Viking high seat crafted in central Norway in 1,000 years

• 

  Researchers are now able to detect aggressive prostate cancer­

• 

  Can desert sand be used to build houses and roads?

• 

  This is why girls are happiest at school

• 

  This is what ADHD feels like for an 11-year-old girl

• 

  Half of all men over 60 have prostate cancer: A new AI tool could help doctors