Though health experts have largely focused their research on the effects of obesity and pregnancy on women, new studies reveal obesity can also negatively impact men's sperm resulting in poor pregnancy success.

Conducted by reproductive experts from University of Melbourne's Department of Zoology, the study used in vitro fertilization (IVF) on animals to understand the effects of paternal obesity on embryo implantation into the womb and fetal growth.

"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," said Professor David Gardner, one of the study authors.

Natalie Binder, who is a PhD candidate at the University of Melbourne, created the embryos from normal weight and obese male mice, which were fed the equivalent of a western diet for 10 weeks.

The study found that paternal obesity negatively affects the development of the egg, as well as negatively impacts the success of embryo implantation into the womb.

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

In addition, placental weight and growth was substantially lower for embryos that were fertilized with sperm from obese males.

According to the World Health Organization, 75 percent of Australian men are obese or overweight, which exceeds the global average rate of 48 percent. Professor Gardner also found the rate of obesity among men in their reproductive age has tripled in the last three decades.

"Our study provides more information about the impact of obesity in men and their ability to start a family and the need to shed kilos in preparation to conceive," researchers said. 

This study will be presented at the Annual Scientific Meeting of the Endocrine Society of Australia and the Society for Reproductive Biology.