THE competence of diligent dads helping out at home is damaging the self-esteem of "super-mums" who feel caught between work and traditional child-rearing roles, according to a new study.

According to a LiveScience report, the University of Texas at Austin interviewed 78 dual-earner couples who had eight-month-old infants, measuring them on two types of self-esteem - self-liking and self-competence.

Researchers asked the parents to talk about their partner's strengths and weaknesses and rated their responses.

They found that among mothers who thought their partners were competent caregivers, the more time those fathers spent alone with their children, the lower the mother's self-competence rating was.

"In American society, women are expected to take a main role in parenting despite increasingly egalitarian sex roles," study researcher Takayuki Sasaki said.

"Thus, we believe that employed mothers suffer from self-competence losses when their husbands are involved and skillful because those mothers may consider that it is a failure to fulfil cultural expectations.

"Husbands do not suffer from self-competence losses even when their wives are involved and skillful because that is consistent with cultural expectations."

Not surprisingly, mothers were found to spend nearly three times as much time child-rearing by themselves as their husbands did.

And this was noticed by husbands who gave their wives top marks in parenting skills.

In contrast they got a much lower rating from the mothers but even so, the women often said their husbands were good parents.

"Many wives would say care-giving by their husbands is helpful but at the same time wives give their husbands negative feedback because their husbands' care-giving style is different from their own," Ms Sasaki told LiveScience.

"For example, a wife appreciates when her husband feeds their baby but also tells her husband that after all it makes more work because the way the husband feeds is messy."