For a long time, I’ve joked about my “baby bicep.” You know, the one in the arm that you’re always holding a baby in, the one arm that gets disproportionately strong? It’s a very real phenomenon, I assure you. To this day, even though my youngest is two years old, I still have it. And I know I’m not alone — many moms in my circle of friends have their own.
Now we’ve discovered that there is actually a super scientific reason as to why most caregivers tend to hold a baby on one side.
According to research, between 70% and 85% of women tend to hold their babies on the left side. You may think that this is because most moms are right-handed, but even mothers who are left-handed tend to hold their babies more on the left (although proportionally, it’s a smaller number than right-handed mothers).
Now, think about what side you hold your baby on the most. Is it the left? It is, isn’t it? You’re reading this thinking, OMG, I do hold my baby more on the left! I wonder why that is!
Well, wonder no more.
A new study suggests that the reason that most caregivers tend to hold babies on their left side has to do with how the brain works. Our left side sends signals to the right side of the brain, which is the side responsible for tasks such as reading social cues, focusing our attention on one thing, and relationship building.
The right side of our brain is fed signals from the left side of our visual and auditory fields, looking for cues from the environment, scanning faces, and translating those cues into messages in our brain. So in keeping a literal eye and ear on our babies from the left, the right side of the brain is able to do its job better, constantly assessing if our kids are OK or if they need anything from us, all while building a bond with them, even while we go about other tasks in our day. Basically, the right side of your brain is better suited for taking care of babies and it needs the left side of your vision to tell it what to do.
Cool, right?
By observing over 300 typically developing children, along with other mammal animals, researchers found that many mothers and caregivers tend to keep small children cradled on their left sides. They also watched what happens when a young animal approaches his or her mom, noting if the offspring approached the mom on the left or the right side.
Say you’re loading the dishwasher and your toddler comes up behind you to wrap himself around your side — which side does he choose? Or say you’re out in public and your preschooler nestles under your arm in a sudden bout of shyness — which side does she choose?
More often than not, the researchers found, children choose to hover near their caregivers on yes, the left side.
Interestingly enough, the older study showed that the “left side, strong side” rule wasn’t as true for males as it was for females, suggesting that their right side was more hardwired for other survival tasks as opposed to just getting the baby to survive. However, another study suggested that although males showed no preference for holding babies to the left side before they actually became fathers, once they did, they showed a significant preference to left-sided holding too.
Previous studies have also suggested that there are other factors at play for the left-side bias, such as the fact that it keeps the baby closer to the mother’s heartbeat, calming the baby and regulating his or her own heart rate. It also allows the baby better advantage to turn its head and not suffocate if it was being cradled against mom while she was running from a predator or something. Left-sided holders were also found to report better relationships with their own parents, while right-sided holders reported more anxiety in general about pregnancy, delivery, and parenthood.
It’s also crazy when you think about the fact that if you’re holding a baby on your left hip, the baby’s right ear will be closest to your mouth, absorbing more of what you say throughout the day — and guess which side of the brain controls things like language development and function? Yup, you guessed it: the left. (Remember, the brain gets signals from the opposite side, so the baby’s right side would be kicking messages to its left brain.) So it’s a win-win for both mom and baby.
Let’s hear it for science, people.