My baby is adorable and sweet but why do I want to kiss her ALL the time?
As I become more established as a new mom, I’m learning that the bond between parent and child is a truly unique and deep one. As soon as I met my daughter, I thought she was the most amazing little person on the planet, but that was just the beginning of my relationship with her. Unsurprisingly, over the past months, my attachment has only grown stronger as I clock more and more hours with her, learning how to understand what she is communicating to me with her tiny baby gestures and noises. In the first few weeks of life with her, I noticed that I would constantly be giving her little kisses- during any activity. When I picked her up, I’d plant a couple of kisses on her head. When I looked at her, I’d give her kisses on her cheeks. When I changed her diaper, I’d kiss her feet and toes. I know I loved her and thought she was the cutest little baby I’d ever met, but I wondered whether there is more to my instinct to kiss her all the time. Could there be some additional benefits to kissing my baby?
While evolutionary explanations for behaviors and traits are virtually impossible to prove, what we know about the infant-mother relationship indicates that yes, there absolutely could be evolutionary benefits for kissing your baby all the time. These benefits are both for the immune health of my baby, as well as her emotional development. Let’s start with the direct, biological benefits:
The impact of kissing my baby is essentially a method for me to sample pathogens (disease-causing agents) on her body e.g. on her face, her hands, etc. When I kiss her, I am picking up potential disease-causing bacteria, viruses, fungal spores, etc. that are on the surface of her skin. Why might I want to do this, you might be asking? In order to understand why we need to get into a little more depth about how the immune systems of newborn infants function to protect them.
The immune system is highly complex and dynamic network of cells and tissue that protect us from invading pathogens. One of the ways our immune system allow for long-term protection from infection is by creating molecules called antibodies, which are used to flag invaders to accelate there subsequent destruction by specific immune cells. The neat thing about antibodies is that the information to make them is stored in immune system “memory” cells, who bring out the antibodies only when the same pathogen returns, allowing you to fight it off quickly. This is called adaptive immunity because it develops in response to the environment that the person is exposed to throughout their life. Since newborn babies aren’t exposed to pathogens in the womb, their adaptive immune systems is immature, making them more susceptible to infection.
In a previous post, I explained how breast milk provides healthy microbiota to the neonate, helping develop a healthy gut microbiome. Of course, that’s not nearly the only benefit of breast milk. A mother’s milk contains many of her antibodies, which help the baby fight off many potential infections, as well as a whole host of other immune components that strengthen the baby’s immune response. What’s especially neat about this system is that while levels of these immune components is highest when the infant is first born and decrease over time, studies have show levels increase again when the mother is exposed to infectious agents. This means that the maternal milk consistently provides protection but also adjusts according to the dangers in the infant’s environment, passing additional and targetted immune support when a new and potentially dangerous pathogen is present.
An interesting sidebar: studies coming out now show that breastfeeding mothers who get the COVID-19 vaccine may transfer immunity to their baby too. Researchers found immune response indicators in the form of COVID-19 specific antibiotics in breast milk just one week after the mother’s first vaccination. Good news for moms and babies: you both get protection with only one shot!
So now, when a mother plants kisses all over her baby, in addition to being warm and sweet to her baby, she is doing reconnaissance work to figure out what pathogens are coming for her baby. Then, with that new information in her own body, her own immune system can bring out the defenses to fight off the pathogen, as well as show her baby how to do the same. There are a lot of battles going on with your baby and you probably didn’t even notice it!
But that’s not all- kissing and being close to your baby is beneficial beyond just protection from disease. Numerous studies have reinforced the importance of close, skin-to-skin contact between mother and newborn infant for a range of physiological benefits such as decreasing stress hormones and stablizing heartrate. But the effects of maternal tenderness seem to span far beyond those early months; a recent study found that infants with more highly affectionate mothers at 8 months demonstrated significantly lower levels of distress and anxiety as adults. While kissing wasn’t direclty evaluatedi in this study, it’s safe to assume that it likely was one of the ways mothers expressed their affection. All this to say, kissing and cuddling your baby not only feels nice at the time, but also likely will have ripples of impact on your baby in distant years to come.
To be honest, I didn’t really need the scientific evidence to persuade me to continue kissing my baby girl but it’s good to know that it has a purpose beyond the present moment. Maybe one day she’ll get tired of my hugs and kisses, but until then, I’ll be doling them out without inhibition!
Works Cited:
Baird, Jill K., Shawn M. Jensen, Walter J. Urba, Bernard A. Fox, and Jason R. Baird. “SARS-CoV-2 antibodies detected in human breast milk post-vaccination.” medRxiv (2021).
Hane, A. A., & Fox, N. A. (2006). Ordinary variations in maternal caregiving influence human infants’ stress reactivity. Psychological science, 17(6), 550-556.
Hassiotou, F., Hepworth, A. R., Metzger, P., Tat Lai, C., Trengove, N., Hartmann, P. E., & Filgueira, L. (2013). Maternal and infant infections stimulate a rapid leukocyte response in breastmilk. Clinical & translational immunology, 2(4), e3.
Jackson, K. M., & Nazar, A. M. (2006). Breastfeeding, the immune response, and long-term health. The Journal of the American Osteopathic Association, 106(4), 203-207.
Laouar, A. (2020). Maternal leukocytes and infant immune programming during breastfeeding. Trends in immunology, 41(3), 225-239.
Maselko, J., Kubzansky, L., Lipsitt, L., & Buka, S. L. (2011). Mother’s affection at 8 months predicts emotional distress in adulthood. Journal of Epidemiology & Community Health, 65(7), 621-625.
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