Men can take the commonly prescribed diabetes drug metformin without concern for birth defects in their children, according to a large study published on Wednesday.
Analyzing over three million pregnancies in Norway and Taiwan, researchers found no link between the use of metformin by fathers in the three months prior to conception—a critical period for sperm development—and the occurrence of birth defects.
Metformin is a relatively inexpensive generic medication typically prescribed as the first-line treatment for Type 2 diabetes, which is the most common form of the disease.
A 2022 study from Denmark had suggested a 1.4 times higher risk of birth defects in boys whose fathers were taking metformin, but subsequent studies have not confirmed this association.
In June, two studies published in the Annals of Internal Medicine indicated that neither maternal nor paternal metformin use increases the risk of congenital malformations.
The combination of data from two different populations in Norway and Taiwan enhances the reliability of the new study’s findings, according to Dr. Allan Pacey, a male reproductive health expert at the University of Manchester in the UK. He stated, “The absence of a link between a father’s metformin use and birth defects makes sense, as there was never a plausible biological mechanism to support such a conclusion.”
Dr. Pacey, who was not involved in either study, noted that the new paper likely found no connection due to improved data quality. “Both analyses were well conducted, but this study accounted for many more confounding factors,” he explained.
