Want a better relationship and a better sex life?

The research was presented Aug. 23 at the annual meeting of the American Sociological Association.

Daniel L. Carlson, along with graduate students Sarah Hanson and Andrea Fitzroy used data from more than 900 heterosexual couples' responses in the 2006 Marital Relationship Study (MARS).

The researchers found that when women were responsible for most or all of the child care, both parties reported both the lowest quality relationships and sex lives.

"The important point to be made is that when we're looking at child care, the difference that we find is really between arrangements where the mother is largely responsible for child care and everything else," Carlson said.

They concluded that beyond splitting child care responsibilities equally, dads in a heterosexual relationship could take on the majority of child-care responsibility without negative effects on the quality of the couples' relationships. These couples had just as much sex as couples with egalitarian arrangements, and were just as satisfied with the amount of sex they were having.

"What we find is that there's generally little to no downside to men being largely responsible for child care," Carlson said. "We conclude that being an engaged father is very important to men. If it weren't, we wouldn't see such a high level of satisfaction. It suggests that father engagement and sharing child care with one's partner is important to both sexes."

There is one caveat, however.

Carlson said that when men do the majority of the child care, their female partners exhibited the highest overall satisfaction with their sex lives, but men demonstrated the lowest overall satisfaction with their sex lives.

The research was limited in some respects, including the fact that only heterosexual couples, and no same-sex couples, were studied. Although the researchers examined five different kinds of tasks across three dimensions of child care, the measures of child care were fairly limited, Carlson said, especially when it came to physical child-care tasks.

"We only had one physical task, and that task revolved primarily around playing with the child, including sports and games, but nothing about who feeds or bathes the child," he said. "The latter physical, instrumental tasks have traditionally been the responsibility of women."

Carlson also wants to learn more about the mechanisms behind why these couples with more egalitarian child-care arrangements reported better relationship quality and sex lives.

"We are trying to understand what is it about sharing that couples view so positively," he said.