Ever noticed that you prefer to carry your baby like this? It's not a coincidence.

Picture: iStock

The next time you're holding your baby while you walk around the house, take notice, are you holding them to your left? Science says most of us are and the reason why is fascinating.

The favouring of one particular side when holding your baby is not something you would necessarily notice straight away. But this tendency in mothers, human and otherwise, is one which has had scientists scratching their head for a long time.

Previous research has indicated that 70–85 percent of women and girls show a bias to hold infants, or dolls, to the left side of their body. This bias doesn't only crop up in motherhood either, little girls of preschool age have demonstrated the left carrying bias too.

Interestingly, this bias is not matched in males. While dads tend to hold their babies on the left, males who are not fathers are far more likely to show no bias at all.

My lopsided back is a case in point. See how much higher my left side is to the right? That what you get from carrying a miniature heffalump on your hip for three years. Source: Donné Restom.

For years, theories have been tossed about in an attempt to explain this preference. Scientists have delved into studies around handedness, proximity to mum's heartbeat, left breast sensitivity and socio-psychological factors.

But recent studies are showing that the truth is far more cerebral.

It's about how our brains talk

When a baby is held on the left, the right side of the mother's brain lights up, and this physical activation of the right side of the mother's brain helps her bond with her baby.

This is how it works in layman terms:

Physical touch on the left side of the body is matched with a response in the right side of the brain. This relationship between one side of the body and it's opposing side of the brain is called lateralisation. The right side of the brain is the side responsible for language and interpreting emotional signals, amongst other things. Therefore, when a baby is held on the left, the mother better able to interpret it's physical and emotional cues.

This is how the latest piece of research, published in Nature Ecology and Evolution, describes it: "The position of an infant on the mother’s left side may optimise maternal monitoring, by directing sensory information predominantly to the mother’s right hemisphere." Kapiche?

What is fascinating is that we're not the only animals on the planet to do this. Many mammals do.

This Humpback baby hangs left. Source: iStock.

All the wonders of the world

The researchers of this study watched a whole lot of mammalian species; wild horses, reindeer, walruses, kangaroos and whales to name a few.

Not only did mothers keep their babies to the left, but the infants when able to make their own choices, chose to hang to the left of their mothers.

Amazing, isn't it?!