MANHATTAN, KAN. -- We see it in the movies and on television when a character realizes they desperately want to have a child. Often it is connected with a ticking biological clock. Or we may experience it ourselves when we see baby toys and clothes in the store. "It" can be summarized in two words: Baby fever.

Not only does the phenomenon called baby fever exist, it is found in both men and women, according to researchers from Kansas State University. Gary Brase, associate professor of psychology, and his wife, Sandra Brase, a project coordinator with the university's College of Education, have spent nearly 10 years researching baby fever: the physical and emotional desire to have a baby.

"Baby fever is this idea out in popular media that at some point in their lives, people get this sudden change in their desire to have children," Gary Brase said. "While it is often portrayed in women, we noticed it in men, too."

The Brases' interest in studying baby fever started shortly after the birth of their second child.

"I noticed a distinct difference in my desire to have more children," Sandra Brase said. "Although one hears about people having baby fever from friends, family and in the media, I was curious if there was a scientific explanation for the presence or lack of it in both women and men."

While some research has looked at the demographic and sociological aspects of having children, there had been no previous study from a psychological perspective, Sandra Brase said. The Kansas State University research appears in the upcoming issue of Emotion, which is published by the American Psychological Association.

The researchers started by applying three different theoretical viewpoints about why baby fever might exist and where it came from:

The sociocultural view: People want to have a baby because they are taught gender roles. Women think they should have children because society says that is what they are supposed to do.

The byproduct view: Humans experience nurturance. When they see a cute baby they want to take care of it, and that makes them want to have a baby of their own. Baby fever is a by-product -- it is nurturance misplaced.

The adaptationist view: Baby fever is an emotional signal -- like a suggestion sent from one part of the mind to the other parts -- that this this could be a good time to have a child.

The researchers then performed studies to understand people's desires, particularly the desire to have a baby.

"Sometimes you may have a desire to have a baby, sometimes you have desires to have money or be famous or have sex," said Gary Brase, whose research focuses on judgment and decision-making. "We asked people to tell us where these desires ranked."

The researchers found several interesting results: First, that baby fever did exist and it existed in both genders. But how frequently a desire for a baby occurred varied according to gender. Women more frequently desired having a child than having sex. Men were the opposite and more frequently desired sex than having a child.

"We found this kind of ironic because sex and having a baby are causally related," Gary Brase said.

The researchers also asked people to describe what led them to want and not want to have a baby. Based on these responses, the researchers created a questionnaire that asked participants their attitudes toward children and fertility. They surveyed college students and also used an online survey to reach a wider range of participants.

"The idea that gender role or misplaced nurturance are the major driving forces didn't get a lot of support from our study," Gary Brase said. "It is something much more fundamental than that."

Rather, the researchers found three factors that consistently predicted how much a person wanted to have a baby. The first factor was positive exposure -- such as holding and cuddling babies, looking after babies and looking at baby clothes and toys -- that made people want to have a baby. The second factor included negative exposure -- such as babies crying, children having tantrums and diapers, spit-up or other 'disgusting' aspects of babies -- that made people not want to have a baby. The third factor included trade-offs that come with having children -- education, career, money and social life.

"We had people who were high on the positive aspects and they see all the good things about babies and want a baby," Gary Brase said. "We also had people who were high on the negative aspects and absolutely do not want to have babies. Then we had people who were high on both positive and negative aspects and were very conflicted about children.

"Having children is kind of the reason we exist -- to reproduce and pass our genes on to the next generation," he said. "But economically, having children is expensive and you don't get any decent financial return on this investment. And yet, here we are, actual people kind of stuck in the middle."

The researchers plan follow-up studies that focus on the role of hormones and why people might experience high and low levels of baby fever.

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