Babies are more likely to be small for gestational age if their mothers have PCOS, possibly due to placental dysfunction, researchers say.

While PCOS is associated with subfertility, metabolic disease and pregnancy complications, previous studies of PCOS and neonatal anthropometric measures have been contradictory.

The latest study in JAMA Network Open found that maternal PCOS was associated with lower birthweight (mean difference 133g), birth length (mean difference 3cm) and head circumference (mean difference 3cm) after adjusting for confounding factors such as smoking, maternal age and maternal BMI.

This was based on 400 mother–child dyads, drawn from the placebo groups of three randomised controlled trials that assessed metformin treatment for pregnant women with PCOS.