A man's self-image is hugely boosted after he becomes a father - unlike women who often feel less physically attractive, according to new research.
The University of California Santa Barbara study, published in the Journal of Gender Studies, found that husbands who had a child felt significantly more attractive after their child was born.
The data for the research was drawn from marriage registration records of two mid-size communities in Washington State in 1991 and 1992.
It examined 182 newlywed couples from Washington State, 48 of whom had a child, and asked them to rate how attractive they felt over their first two years of marriage.
Women and men had greatly opposing results, which didn't surprise Paul Jose, Associate Professor at Victoria University of Wellington's School of Psychology.
"In some ways having a child causes a more dramatic role shift for men than it does for women, namely being perceived as a nurturing caregiver to an infant, and it probably causes them to have a more dramatically different view of themselves.
"Underlying that is the evolutionary theory of the human species that men are much more interested in being successful at reproducing. Feeling attractive in yourself is a side benefit of realising that you have been successful in procreating."
Perhaps men also had more of an opportunity to reflect on the legacy that they would be leaving behind through their child.
"There are certain biological necessities that preface the woman into breast feeding while the man doesn't necessarily get involved. Waking up in the middle of the night is something that is kind of optional for the man in a way that it is not for the woman.
"Male and female roles are much more egalitarian than they used to be, but they're not perfectly egalitarian and they probably never will be given the biological constraints having a child has on the woman."
Having hoards of women coming up to them to coo at their babies was also likely to boost a man's self esteem. "It's central to this evolutionary view that a man who is able to procreate is by definition attractive."
Fatherhood takes comfort to another level
Steve Anderson says becoming a father to Cato means he's more engaged with mothers in the office.
Since the birth of his first child, Steve Anderson has never felt so comfortable about himself.
The Auckland father says he doesn't feel more attractive since son Cato arrived five months ago but has new priorities. Perhaps that new sense of confidence radiated on to other people, he said.
"The thing is [women are] not so much interested, they're more relaxed," Mr Anderson said. "I guess you don't think about your appearance as much because you've got a young son, you're in a relationship. [But] whether you're just more comfortable in your own skin because of that is a possibility."
The 36-year-old accountant said he also found himself more engaged with mothers in the office, perhaps because sharing parenthood stories broke down barriers.
However, the first two months after Cato was born were "to be honest ... very difficult".
"Once you get used to and accept the change then it really does become easier.
It becomes really enjoyable."