Peter Mallet / Stone / Getty Images It seems almost ludicrous today that anyone could ever think otherwise. But this idea was by no means taken for granted just 100 years ago. Early 20th-century child-rearing guides warned parents not to kiss their babies or cradle them too much, lest the children become spoiled. Spock taught his readers that babies were little people with their own emotional needs, and that they should be cherished, not encouraged to play by the rules of adult life as soon as possible. "Children are driven from within themselves to grow, explore, experience, learn, and build relationships with other people," the latest edition of Baby and Child Care now reads. "So while you are trusting yourself, remember also to trust your child."

If at some point you’ve had an irrepressible, inexplicable urge to make a baby, you may be interested to know there’s a term for that — baby fever — and that it’s a bona fide physical and emotional phenomenon, according to research in an upcoming issue of the journal Emotion.

Although it may be linked to another baby-craving phenomenon commonly known as the “biological clock,” in which women realize their biological baby-making window is dwindling, baby fever isn’t specific to women. Men can get all goo-goo-ga-ga too, say a husband-wife team at Kansas State University who first wondered about the sensation after their second child was born.

Gary and Sandra Brase started with a formal survey designed to figure out if baby fever actually exists. They learned that both men and women can develop it, although its intensity varies from person to person and within the same person over time. “Baby fever is normal, it varies a lot, and people don’t have to feel it,” says Gary Brase, associate professor of psychology at Kansas State University.

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The Brases then launched an analysis measuring baby fever in various ways. In one study, they asked people to rank the importance of being famous, having sex, having money and having a baby. Here’s how those results broke down: “Women tended to rate having a baby as more important than men did, and men tended to rate having sex as more important than having a baby,” says Gary Brase.

The researchers also looked at three potential explanations for baby fever: the sociocultural view, the byproduct view and the adaptationist view. According to the sociocultural view, people — especially women — are acculturated to crave babies. “People might think they want to have children because they are supposed to have children,” says Brase.

Brase and his wife asked 80 college students of varying ages to rate how frequently they had a desire to have children, then administered a test that assessed how strongly they affiliated with particular gender roles. After sorting the data, according to Gary Brase, they found that the sociocultural view was “not a great predictor of how strongly people felt a desire to have children.”

The byproduct view holds that people want to have children to fulfill an urge to nurture. But the Brases found that this theory didn’t tell the whole story either.

Finally, the Brases trained their lens on the adaptationist view, which theorizes that baby fever is an emotional signal that subconsciously hints to the brain that it might be a good time to have a baby. When testing out this hypothesis, the Brases found that positive exposure to babies (ones that coo and smile and smell nice) made people want to have kids, while negative exposure (crying, stinky infants) made people shy away from the idea of parenthood. Another factor they considered involved the inevitable trade-offs involved in having children — less time, less money and less freedom to do what you want, when you want.

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“People’s desire to have children is most influenced by the positive and negative interactions and the trade-offs,” Brase concludes.

The Brases haven’t looked in-depth at how people’s baby-lust evolves once they have children. But they have noticed that women’s average baby-fever rating went down after they had children, while men’s went up. What gives? “I have noticed the change in my own desire after I had kids,” says Brase. “Babies were more attractive and I wanted to hold them.”

Perhaps women are more realistic, recognizing the enormous amount of work that baby fever, actualized, takes? “Maybe,” surmises Brase, “women were starting at a higher place, realizing raising children is really difficult.”