Oh, the delicious scent of a new baby. It turns out that the fact you want to gobble up your sweetie isn’t your fault—it’s biology. Scientists have recently learned that in new mothers, the body odour of newborns activates the centres of the brain that perceive rewards and pleasure—and makes those moms hungry for more.
Donna Bell of Edmonton knows all too well the power of that wonderful aroma. She describes the scent of her three-month-old, Matthew, when he was a newborn as “kind of musky but sweet, too. I’d smell him on my clothes, and I’d want to rush home and nurse him.”
Studies in animals have shown that all mammals, from mice to primates, use their sense of smell to establish and develop a mother-infant bond. If mothers and babies can’t smell each other, they might not become as strongly attached.
Newborns also benefit when they’re held more. Numerous studies point to the physical and developmental advantages of lots of cuddling, and anything that increases mothers’ desire to breastfeed is good news for babies.
But the significance of smell to human mother-infant bonding had never been studied before with neuroimaging. Johannes Frasnelli, a post-doctoral researcher in the psychology department at the University of Montreal, set out to change that. “We tend to think of body odour as this negative thing, and I think that’s why we haven’t studied its importance yet,” he says. “But our sense of smell is just as vital as sights and sounds for understanding the world around us, and when it comes to developing relationships, smell may be even more important.”
To investigate, the researchers froze pyjamas that newborn infants had worn for two nights immediately after their birth. Up to six week later they then presented the jammies to two groups of 15 women (all of them unrelated to the babies in the study) to smell.
The first group of lucky sniffers was composed of women who had given birth three to six weeks before the study, and the second group had never given birth. The researchers performed brain-imaging scans while the women inhaled. The resulting pictures showed that the new moms got a greater hit of pleasure and a sense of reward than the non-mothers. Evolutionary bonus? The feel-good centre that was activated in the mothers’ brains is also associated with learning. “If you receive a reward for a certain behaviour—in this case, holding and smelling a baby—you’re likely to want to continue that behaviour,” Frasnelli explains.
This is how it works for Natalie Russo from Montreal, mom of two-month-old Chloe. “When we’re having a hard time, just smelling her puts things into perspective and makes me think, ‘We’ll figure this out together.’”
Frasnelli emphasizes the importance of this built-in reward effect for new mothers, and likens it to training for a marathon.
“It’s definitely not pleasant to run a marathon, but if you want to do it, it’s a very satisfying experience. Having a newborn can also be very trying, but parents find it extremely pleasurable and gratifying.”
As to what causes that magical newborn odour, nobody knows for sure, but researchers theorize it could be remnants of amniotic fluid or vernix caseosa, the cheese-like substance that covers babies at birth.
Whatever it is, for new moms, it turns out that newborns really are that little cupcake treat at the end of a hard week.
Just like you love the scent of your baby, your newborn loves to smell you nearby, too. If your little fusspot won’t settle down, try sleeping with your baby’s pyjamas or a swaddle for a night or two to infuse it with that comforting Mommy or Daddy smell.
This article was originally published online in December 2013.