Body odor conveys a wide variety of cues about gender, age, family, stress, and disease states. Body odors are also believed to direct mating and bonding between individuals. Now, a new study finds that newborn body odor may contribute to building maternal-child relationships.

A team of researchers in Germany conducted functional magnetic resonance imaging of the brains of 30 women. Half of the women had given birth within the previous three to six weeks, and the other half had never given birth. The brains of the women were imaged while they sniffed pajamas worn by newborn babies for the first two days of life. Both groups experienced increased dopaminergic responses, which are critical to the brain’s reward pathways. However, the new mothers experienced a significantly higher activation than the childless women.

For a mother, the smell of a newborn baby — not even her own, according to this study — provides a dose of dopamine and fills her with feelings of positivity and well-being, which acts as a reward for cuddling and snuggling the baby. Likely, this maternal physiological response aids in sealing a bond with her child. A mother craves the reward associated with being close to her baby and this motivates her attitude and behavior toward her newborn.

The response is similar to the dopaminergic rewards that are active when addicts take drugs or hungry people eat food. An activity that satisfies a craving has the potential to activate the brain’s reward centers, and, therefore, some researchers have claimed that mothers may be, in a sense, addicted to their babies.

Mammals — both humans and non-humans — have long been known to release olfactory cues to their offspring. These cues control an infant’s mood, direct attention, delay stress responses, stimulate breathing, promote feeding, and even boost learning. Maternal odors offer clues to an infant as he or she explores the body surface and environment of the mother. We are now learning that the baby’s odors may likewise aid the mother. All of these stimuli ultimately support the survival and growth of a newborn.

Much attention has been paid to auditory and visual stimuli in parental bonding, but this study offers evidence that olfactory signals may be just as important in creating human bonds. The dopaminergic activity initiated by the sensory signals is critical to rewarding satisfying behavior, and what is more satisfying than a mother’s love for her child?

References

Lévy F, Keller M, & Poindron P (2004). Olfactory regulation of maternal behavior in mammals. Hormones and behavior, 46 (3), 284-302 PMID: 15325229

Lundström JN, Mathe A, Schaal B, Frasnelli J, Nitzsche K, Gerber J, & Hummel T (2013). Maternal status regulates cortical responses to the body odor of newborns. Frontiers in psychology, 4 PMID: 24046759

Schaal B, Coureaud G, Doucet S, Delaunay-El Allam M, Moncomble AS, Montigny D, Patris B, & Holley A (2009). Mammary olfactory signalisation in females and odor processing in neonates: ways evolved by rabbits and humans. Behavioural brain research, 200 (2), 346-58 PMID: 19374020

Sullivan RM, & Toubas P (1998). Clinical usefulness of maternal odor in newborns: soothing and feeding preparatory responses. Biology of the neonate, 74 (6), 402-8 PMID: 9784631

Image via djedzura / Shutterstock.