Metformin use by men within three months of conception is linked to a 40% increase in major birth defects of their babies.
Metformin is a diabetes and anti-aging drug. This large Danish study followed more than 1 million births from 1997 to 2016. The findings were published in the journal Annals of Internal Medicine.
The study found the frequency of birth defects was 4.6% in children whose father took Metformin during preconception. In the babies born to dad’s who had type 2 diabetes but were not taking Metformin the frequency was 3.1%.
Fathers who took metformin before or after the three-month window prior to conception did not put their baby at increased risk of a birth defect.