For women trying to encourage their partners to take more interest in fatherhood it could be the ultimate incentive.
Research has shown that men who spend more time looking after their children have more sex and better relationships. By contrast, women who do most of the childcare saw their relationships and sex lives decline.
Sociologists from Georgia State University, in the US, grouped 487 couples into three categories: those in which women did most of the childcare, those in which men took the leading role, and couples who shared the childcare.
The researchers found that when women were responsible for most or all of the childcare, men and women reported lower-quality relationships and sex lives compared with couples that split the childcare equally.
"One of the most important findings is that the only childcare arrangement that appears really problematic for the quality of both a couple's relationship and sex life is when the woman does most or all of the childcare," said Dr Daniel Carlson, an assistant professor of sociology at Georgia State University.
Fathers who took on most of the childcare reported good relationships and had just as much sex as those couples who shared the load.
However, they saw the quality of their sex lives diminish, suggesting that splitting childcare makes for the best relationships and happiest sex lives overall.
Dr Carlson said: "We are trying to understand what it is about sharing that couples view so positively."
A previous survey by Yano, the parenting website, found that nearly four in every 10 new mothers and fathers confess they find their partners less attractive after having children, with 63 per cent admitting their sex lives have deteriorated.
More than six in every 10 parents said their intimate relationships had deteriorated since having children, with 28 per cent having sex just once a month, 5 per cent once a year and 7 per cent not at all.
The Telegraph, London