The special bond between a mother and her newborn baby might have something to do with the unique odor her offspring emits. Apparently the smell of newborns evokes a biological response in women that enhances their mood and activates caregiver instincts, researchers say.
A 2013 study published in the journal Frontiers in Psychology found that mothers and non-mothers experience a rush of dopamine — the feel-good neurotransmitter — when they encounter the scent of infants. (The study didn't look at how the smell affected men.) For mothers, however, the response was demonstrably stronger.
"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," study author Johannes Frasnelli said in a press release. "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."
How researchers discovered this response.
Earlier research established that mothers and their infant children were able to identify each other by smell, but there weren't any studies examining how the smell of newborn babies effected mothers' brains. To explore the theoretical connection, researchers at the University of Montreal asked 30 women (15 who had given birth around the time of the study and 15 who didn't have children) to identify a series of scents while their brain activity was measured.
Among the various smells included in the olfactometer was that of a newborn baby, which was extracted from cotton clothing the infants wore. Just as the smell of tasty foods stimulated a region of the brain associated with pleasure, the infant smell caused the dopamine pathway of the study participants to light up, especially for new mothers.
"It is possible that childbirth causes hormonal changes that alter the reward circuit in the caudate nucleus, but it is also possible that experience plays a role," Frasnelli said. "What we know now and what is new is that there is a neural response linked to the status of biological mother."
