Confirmed: Obesity is bad for sperm

Wannabe dads should get in shape before trying to conceive, suggests a new study that found a man’s obesity may have a negative impact on his sperm.

Researchers at the University of Melbourne used in vitro fertilization (IVF) on mice to create embryos from the sperm of normal weight male mice and obese ones. The fatter dads had been fed the mouse equivalent of a fast food diet for ten weeks, a statement from the university explained. The researchers then analyzed the effects of the father’s obesity on embryo implantation and fetal development.

“We found that development was delayed in the fetuses produced from obese fathers,” researcher Natalie Binder said in the statement. “The rate of embryo implantation into the womb and fetal development decreased in these animals by up to 15 percent.”