In small follow-up studies (25 and 141 children) in mothers with PCOS exposed to metformin or placebo, metformin showed no effect on children anthropometry [12] or an increased BMI and adiposity measurements, except for mothers with high BMI.2 [11] In mothers with gestational diabetes, the BMI of 9-year old children exposed to antenatal metformin was only higher when mothers had a higher pregnancy-BMI (compared to insulin) [52, 53]. This evidence concerns the gene INS and gestational diabetes.