By: Megan Gannon, News Editor
Published: 08/23/2012 02:12 PM EDT on LiveScience

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) 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 10 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."

The study's results will be presented next week at the Annual Scientific Meeting of the Endocrine Society of Australia and the Society for Reproductive Biology. Further research is needed to see if the findings hold up in humans.

If they do, the researchers note, the findings should particularly resonate with Australians. In the country, 75 percent of men are overweight or obese, while about 36 percent of white American men are considered obese, as of 2010, according to the Centers for Disease Control and Prevention.

"Australia has a weight problem; the rate of obesity among men of reproductive age has more than tripled in the last three decades," said researcher David Gardner, also of the University of Melbourne.

"A lot of men don't understand what contribution they're having, but they need to be healthy before conceiving. Sperm needs to be match fit for the games of life, and creating life is the biggest thing that we can do."

Previous research found that obese men are at greater risk for infertility and are more likely to have a lower sperm count than males with a healthy weight. For a mother's part, earlier studies have found that her obesity during pregnancy may increase her kid's risk of developmental delays and for conditions like Alzheimer's and heart disease later in life.

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