Stanford Study shows Birth Defects in Baby Boys linked to Extremely Popular Diabetes Drug

Boys were more likely to be born with genital birth defects if their fathers took the commonly prescribed diabetes drug metformin in the three months before conception, according to a new study by Stanford Medicine investigators and their collaborators in Denmark.

The Stanford study went on to say…

“For women, we know a lot about risk factors. There’s a list of medications that women are not supposed to take when they’re pregnant, for example,” said Michael Eisenberg, MD, professor of urology at Stanford and senior author of the study. “Given that men contribute half the DNA to a child, it makes sense that there could be some effects that travel through paternal pathways as well.”

In fact, the magnitude of the risk associated with metformin in the new study is on par with more well-known maternal contributors to birth defects, such as pregnancy after age 45 — a comparison that Eisenberg calls “sobering.”

Using health-registry data from Denmark that tracked more than 1 million births, the researchers linked men’s use of metformin during sperm development to higher rates of genital birth defects in their sons. It’s notable that the genital birth defects occurred only in boys, and these fathers were less likely to have boys than girls compared with the general population.

These results suggest that metformin affects men’s reproductive health in a way that can harm their sons, though the mechanisms are still unclear.

40% increase in birth defects, study finds.

‘Don’t forget the father’

Should men aspiring to fatherhood avoid this particular drug? “I think that it’s a single study, so it’s hard to change clinical practice based on that,” Eisenberg said. “But for somebody considering fatherhood, this study emphasizes the importance of a father’s health on the health of a child.”

Eisenberg said it will be important to uncover the biological mechanisms at work and to expand the study beyond the relatively homogenous population of Denmark. “Ultimately, before you change guidelines, this should be studied and validated in other populations as well,” he said.

This study brings further awareness that paternal factors can make a difference.

Michael Eisenberg, MD

“When we think about reproduction, we still mostly think about maternal factors, so this study brings further awareness that paternal factors can make a difference,” Eisenberg said. “Don’t forget the father.”

Other Stanford co-authors of the study are professor of biomedical data science Ying Lu, PhD; professor of biomedical data science Lu Tian, PhD; and professor of pediatrics Gary Shaw, Dr.PH.

Researchers from the University of Southern Denmark and Copenhagen University also contributed to the research.

The research was supported by the National Institutes of Health (grants HD096468 and 1UL1TR003142) and the Centers for Disease Control and Prevention.

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