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Diabetes drug use during pregnancy affects child's weight

Children born to mothers who took metformin face increased risk of obesity

Ingrid Torjesen

Wednesday, 28 February 2018

Children may be at increased risk of being overweight or obese if their mothers took the diabetes drug metformin during pregnancy, a study* published in Journal of Clinical Endocrinology and Metabolism suggests.

A growing number of pregnant women are taking metformin to treat gestational diabetes or polycystic ovary syndrome (PCOS), a common cause of infertility, and can put women at risk of developing diabetes and other metabolic health problems.

When pregnant women with PCOS or gestational diabetes take metformin, the medication crosses the placenta and is passed to the foetus.

The researchers invited parents of 292 children who had participated in two previous randomised clinical trials to be part of this study. In the previous trials, pregnant women with PCOS were assigned to take either metformin or a placebo during pregnancy. The researchers reviewed body mass index (BMI) and other measurements for 161 children born following the two earlier studies.

At four years of age, the children whose mothers were randomised to metformin during pregnancy tended to weigh more than the children whose mothers took the placebo. Although metformin did not appear to affect birth weight, the trend became apparent when children reached six months of age. At the age of four years, the children in the metformin group had higher BMI scores and were more likely to meet the criteria for obesity or overweight than children in the placebo group.

"Our findings indicate the offspring of women who took metformin for PCOS during pregnancy are more likely to meet the criteria for obesity or overweight than children whose mothers were given a placebo during pregnancy," said researcher Dr Liv Guro Engen Hanem, of the Norwegian University of Science and Technology in Trondheim, Norway.

"The results were surprising, since limited past research in this area had suggested metformin would have a protective effect on the children's metabolic health.

"Few studies have examined the long-term health of children born to women with PCOS who took metformin," she said. "Our findings indicate more research is needed to determine its effects on children who were exposed in the womb."

*Hanem LGE, et al. Metformin use in PCOS pregnancies increases the risk of offspring overweight at 4 years of age; follow-up of two RCTs. The Journal of Clinical Endocrinology & Metabolism, jc.2017-02419, doi:10.1210/jc.2017-02419.

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