Couples sharing child care duties equally leads to a more satisfying and higher quality relationship and sex life, according to new research.

For the study, the researchers grouped the participating couples - all of whom had children - into three different categories; one group where the women did most or all of the child care, one group where the men did most or all of the child care and one group where child care responsibilities were more or less shared.

Relationship quality was assessed by reported relationship satisfaction and conflict, and the researchers also examined how often couples had sex and how they felt about it.

The lowest quality relationships and sex lives were reported when women were responsible for most or all (at least 60%) aspects of the couple's child care.

"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," says study co-author Daniel L. Carlson, an assistant professor of sociology.

When men took on the majority of child care responsibilities, relationship quality, sexual frequency and satisfaction with sexual frequency were just as high as with couples with shared child care responsibilities.

However, in relationships where men were responsible for the majority of child care, although women reported the highest overall satisfaction with their sex lives, men reported the lowest overall satisfaction with theirs.

Despite this, Prof. Carlson concludes that being an engaged father is important to men.

"If it weren't, we wouldn't see such a high level of satisfaction," he says. "It suggests that father engagement and sharing child care with one's partner is important to both sexes."