https://edition.cnn.com/2022/03/28/health/paternal-metformin-use-birth-defects/index.html 

Men's use of diabetes drug just before conception is linked to a 40% increase in birth defects, study finds

(CNN)Metformin use by men in the three-month period before they conceived a child was linked to a 40% higher risk of birth defects in the offspring, according to a study published Monday in the journal Annals of Internal Medicine.

Metformin is a first-line drug in the treatment of type 2 diabetes.

The research, which was done out of Denmark, used national registries to follow over 1 million births between 1997 and 2016 and compared the risk of major birth defects in babies based on paternal exposures to diabetes medications. The study observed only children who were born to women under 35 and men under 40. Babies born to women with diabetes were excluded