Results from a new trial suggest treatment with metformin could reduce the risk of late miscarriage and pre-term birth in women with polycystic ovary syndrome (PCOS); however, it does not prevent gestational diabetes.
The multi-centre randomised PregMet2 trial took place at 14 hospitals in Norway, Sweden and Iceland between 19 October 2012 and 1 September 2017. It included 487 women with PCOS, aged 18-35 years, who were randomised to metformin (n=244) or placebo (n=243). Participants received oral metformin 500 mg twice daily or placebo during the first week of treatment, which increased to 1,000 mg twice daily or placebo from week two until delivery.
The study identified a non-significant reduction in the composite incidence of late miscarriage and pre-term birth among participants in the metformin group. However, this difference was significant in a post-hoc pooled analysis of individual participant data included with two previous trials (odds ratio [OR] 0.43; 95% CI 0.23-0.79; P=·004).
Metformin had no effect on the incidence of gestational diabetes, a finding the authors described as 'surprising'. Presenting the findings in the Lancet Diabetes and Endocrinology, they said, “there is therefore no evidence to recommend metformin as prevention or treatment for gestational diabetes in women with PCOS."