Fathers Taking Metformin While Trying for Babies May Triple Birth Defect Risk

A study on one million babies in Denmark linked diabetic fathers taking metformin while trying for a baby to triple risk of having a son with congenital disabilities.

One of the genital defects, hypospadias, is a condition when the urethra cannot exit from the tip of the penis. It may be rare, occurring in 0.9% of all babies whose biological father took metformin three months before conception. The findings, according to epidemiologists, are significant because tens of millions of people take the drug worldwide to treat type 2 diabetes, Science.org reports.

The study results

 The research was done in Denmark using national registries, followed by more than one million births from 1997 to 2016. The study involved only children born to women under 35 and men under 40. Researchers did not include babies born to women with diabetes in the study.

The researchers also involved men exposed to metformin if they filled a prescription three months before the conception, the duration it takes for the fertilizing sperm to mature.

As per Daily Mail, fathers who take metformin are more likely to have babies born with genital defects. The defects were around 40 percent more common among youngsters whose fathers had been prescribed the medication.

Of all the babies involved in the research, 3.3 percent were born with one or more major congenital disabilities. However, according to the findings, 5.2 percent of the newborns whose fathers took metformin had genital defects. The team said this corresponds to a 41 percent higher risk than those who did not take it.

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Metformin

Metformin is the first-line drug for treating type 2 Diabetes, CNN reports. 

It is unclear how many men have been prescribed the drug, but records indicate that around 4.7 million people in the U.K. and 37 million in the U.S. are diagnosed with diabetes. 

It reduces the amount of sugar the liver releases into the body, bringing down sugar levels and improving insulin resistance.

According to Germaine Buck Louis, a reproductive epidemiologist at George Mason University, he knew that the study would go viral when he saw the paper.

Metformin is a widely used drug used by young men because of obesity issues. Buck Louis says that it is a potentially huge source of exposure for the next generation.

The article also stressed that the findings are preliminary and observational, and it still has to be corroborated as other factors aside from metformin may have influenced the results. Scientists have cautioned men with diabetes against abruptly stopping metformin before trying to conceive.

The paper's first author, Maarten Wensink, an epidemiologist and biostatistician at the University of Southern Denmark, emphasized that metformin is a safe and cheap drug that controls blood sugar levels. Any change in medication, according to him, is a complex decision that a couple should undergo with their physicians, he said.

Professor Allan Pacey, an andrologist at the University of Sheffield and former chair of the British Fertility Society, said the sheer size of the diabetes pandemic suggests that treatment of fathers-to-be must be studied further as metformin is a drug commonly used in men of reproductive age.

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