They squeal, they scream, they burble and burp -- and according to popular culture (not to mention various episodes of "30 Rock" and "Sex and the City"), nearly every American female over the age of 30 is ga-ga to get their hands on one of them.
Now a new study in the psychological journal Emotion claims that "baby fever" -- that sudden, visceral, and almost irresistible urge to have a baby -- not only exists, it can be found in both men and women.
"Women reported that it happened more frequently and more strongly but it's there for both men and women," says Gary Brase, associate professor of psychology at Kansas State University who along with his wife Sandra Brase, spent nearly 10 years studying the phenomenon.
The researchers, who have two children, first looked at three theoretical viewpoints as to why baby fever might exist and where it could come from. One theory had to do with gender roles, i.e., women think they should have kids because that's what they're taught women are supposed to do. A second theory had to do with nurturing.
"Humans are biological organisms, we have a sex drive and we nurture once a child is born," says Brase. "We looked at whether baby fever was due to people looking at someone else's child and then having that trigger misplaced nurturance. But it wasn't that either."
A third theory had to do with timing -- the brain delivering a signal that this could be a good time to have a child. But when they talked to their test subjects (a total of 337 undergrad students and 853 general population participants gathered via the Web), none of these theories seemed to hold up.
Instead, three factors consistently predicted how much a person wanted to have a baby.
"The first two had to do with the visual sensory things," says Brase. "Seeing a baby, hearing a baby, smelling a baby led some people to want to have a baby."
Conversely, hearing a baby screaming, smelling a dirty diaper or being exposed to spit-up or other "disgusting" aspects of babies, led other people to not want a baby or come down with what you might call "anti-baby fever."
A third factor had to do with trade-offs that come with having children.
"People would say, 'I don't want to have a baby because I don't have money or I don't have time or I don't have a partner,'" he says. "All of the rational thoughts. That showed up as a third factor."
Rachel Kramer Bussel, a 35-year-old writer and editor from Brooklyn, has no doubt baby fever exists. In fact, she knows exactly when she caught it.
"I've wanted to have a baby for about five years, since I turned 30," she says. "I have to force myself to not stare at strangers' children when I'm out. It feels like both this physical tug and an emotional one. There's something about holding a baby close to me that makes me feel like everything is right with the world."
Russell Williams, a 39-year-old software engineer, says he, too, has been bitten by the baby bug.
"I don't get a yearning -- it's not a physical feeling -- but I love being around kids and get my baby fix by babysitting friends' kids," he says.
Williams says his baby jones has even led him to throw a birthday party for the 2-year-old daughter of a female friend, complete with decorations, activities and a Dora the Explorer cake, which he baked himself.
"I always assumed I'd have a family with a kid or two and a wife by now," says the Seattle bachelor. "I enjoy being around kids; it's fun to interact with them. Although it doesn't make my stomach do flip-flops. So maybe my baby fever is more of a cold."