A common reaction in women is to want to “gobble up” a baby that has been placed in their arms, even if it is not their own. New research reveals that this reaction could have biological underpinnings related to maternal functions. For the very first time, an international team of researchers has discovered evidence of the phenomenon within the neural networks associated with rewards.

“The olfactory — thus non-verbal and non-visual — chemical signals for communication between mother and child are intense,” explains Johannes Frasnelli, a postdoctoral researcher and lecturer at the University of Montreal’s Department of Psychology. “What we have shown for the first time is that the odor of newborns, which is part of these signals, activates the neurological reward circuit in mothers. These circuits may especially be activated when you eat while being very hungry, but also in a craving addict receiving his drug. It is in fact the sating of desire.”

For the experiment, researchers used two groups of 15 women and presented each with the odor of other people’s newborns while conducting brain imaging tests. The first group contained women who had given birth 3 to 6 weeks prior to the experiment, while the other group contained women who had never given birth before. All women were non-smokers. The odors of the newborns were collected from pajamas two days after birth.

Although both groups perceived the newborn odor with the same intensity, brain imaging tests showed greater activation in the dopaminergic system of the caudate nucleus in the women who had given birth compared to those who had not.

“This structure plays a role in reward learning,” explains Frasnelli. “And dopamine is the primary neurotransmitter in the neural reward circuit.”

“This circuit makes us desire certain foods and causes addiction to tobacco and other drugs,” says the researcher. “Not all odors trigger this reaction. Only those associated with reward, such as food or satisfying a desire, cause this activation.”

The results of this research show that the odor of newborns does play a role in the development of motivational and emotional responses between mother and child by eliciting maternal functions like breastfeeding and protection. The bond between mother and child  is part of the maternal love feeling and a product of evolution through natural selection in an environment where a bond is essential for newborn survival.

However, this experiment did not determine if the greater activation of the dopaminergic system was due to organic response related to childbirth or was a consequence of the olfactory experience developed by mothers with their own babies. It is also not known if the reaction only occurs in women, since men were not included as part of the experiment.