Father-baby interactions & oxytocin
Why you should be skeptical about research on hormones, but also here's a really cool new study about hormones!
I always thought it was a gendered stereotype that dads “roughhouse” more with their kids compared to moms, and it definitely is, but that didn’t stop me from being absolutely horrified the first time I saw my husband throw our newborn up in the air. Sure, it was more like “less than an inch above his hands” than “up to the treetops,” but still - the horror!
A recent study I saw on Twitter reminded me of this previous (over)reaction and got me thinking more about unique parent-infant interactions. Morris and colleagues (2021)1 were interested in the different ways that fathers physically interact with their babies and how these interactions may be related to oxytocin. I recently discussed the various functions of oxytocin for moms, but there’s research to suggest that it plays a role in parenting behaviors for dads, too. The researchers cite literature from both human and animal studies that suggest that male parents tend to “roughhouse” more with babies, such as throwing babies in the air, carrying them, or bouncing them, as a means of showing affection. Further, other studies show that these behaviors are related to an increase in oxytocin response in dads, suggesting that these behaviors may be important for parent-child bonding.
To better understand these interactions, Morris et al. studied 45 heterosexual dads as they played with their six-month-old infants. First-time dads (along with moms) were videotaped while playing with their babies. The researchers also collected blood samples to assess oxytocin levels from dads after this playtime2. The videotapes were coded by the researchers moment-by-moment for the different ways that dads physically interacted with their babies, including the following types of interactions:
“gentle affectionate touch” (e.g., patting/stroking the baby),
“playful affectionate touch” (e.g., tickling),
“playful proprioceptive touch” (roughhousing, like throwing the baby in the air - the baby had to be moved through space while playing with dad),
“functional proprioceptive touch” (moving the child through space, but not for playful reasons),
“functional touch” (e.g., wiping infant’s mouth),
“touching extremities” (e.g., hand on the baby’s leg),
holding the baby, and
absence of touch.
Overall, they found that the only type of physical interaction that was related to more oxytocin in dads was “playful proprioceptive touch,” i.e. roughhousing, while the absence of touch was related to less oxytocin. In other words, the more dads roughhoused with their babies, the more oxytocin they had after playtime, while the less dads touched their babies at all, the less oxytocin they had. No other type of physical interaction was related to oxytocin in dads.
So does this mean that roughhousing causes increases in oxytocin, or that oxytocin is responsible for my husband throwing our baby up in the air?
Healthy skepticism & how hormones are like eggs (bear with me)
Anytime you read a study (or about a study) that seems to say “X hormone/neurotransmitter/chemical in our body is responsible for Y complicated behavior,” you should be skeptical. Hormones are complicated. Behavior is complicated. As scientists we try to do our best to observe and understand the relationships between these complicated things, but we are susceptible (like everyone) to biases like the narrative fallacy (seeing a sequence of facts and weaving a tidy story to explain how they are related when maybe they aren’t) and mistaking correlation (more roughhousing is related to more oxytocin in dads) as causation (more roughhousing causes more oxytocin in dads). Ninety nine times out of 100 we don’t understand hormones or human behavior enough to say that one causes the other, or is mainly responsible for the other.
To say that oxytocin causes dads to roughhouse with their babies is like saying that eggs cause cake to be created all by themselves. Sure, on average, eggs (oxytocin) may be involved with making a cake (dads playing with their babies), and they may even show up as a core ingredient for many cakes (behaviors), but there are a lot of other ingredients and actions that go into making a cake. Similarly, there are a lot of other physical and psychological processes other than hormones that affect behaviors. Further, there are many cakes that don’t need eggs, just as there are probably many dad-baby roughhousing behaviors that aren’t related to an increase in oxytocin in dads. In fact, there are probably individual dads that show the opposite relationship with playing with their babies and oxytocin.
Conclusions
The authors do not claim that oxytocin causes anything, and they definitely don’t talk about baking, but it can be easy as a reader to make this leap. To say that oxytocin causes or is mainly responsible for dads roughhousing with their kids is not supported by this study, nor is the idea that roughhousing causes an increase in oxytocin. Further, it would be wrong to read this study and conclude, “Oh, so the way that all male parents bond with their children is by throwing them up in the air, and if they don’t, they must not really be connecting with their babies.” Of course dads (just like all parents) differ in how they bond with their babies. Unfortunately, the researchers didn’t ask dads how they felt about their babies, either during the playtime or in general, so it’s hard to know exactly whether or how this increase in oxytocin was related to the parent-child relationship. There are also other unmeasured behaviors - such as how the babies or mothers were acting in the study, or other differences between dads who roughhoused with their children compared to dads who didn’t - that could have been responsible for these differences in oxytocin in dads.
Given these caveats, I still really liked this study. In case you’re not sure, coding moment-by-moment interactions, even during a brief four-minute video, is HARD work, and I love studies that look at behavior in such a nuanced way. The study made me think of all the different ways parents play with and successfully bond with their children, and how different interactions may serve different functions for different people. It will definitely make me think twice the next time I gasp in horror if I see a parent being “too rough” with their baby!
Morris, A. R., Turner, A., Gilbertson, C. H., Corner, G., Mendez, A. J., & Saxbe, D. E. (2021). Physical touch during father-infant interactions is associated with paternal oxytocin levels. Infant Behavior and Development, 64, 101613. https://doi.org/10.1016/j.infbeh.2021.101613
The researchers assay oxytocin from blood samples using two different methods and argue that one is more accurate than the other - I’m not going to get into those details here, though I am only summarizing the results from the “more accurate” method.