Why do newborns move randomly?

Japanese experts say these behaviors prepare newborns’ bodies and senses for other activities, such as crawling or grasping, as they develop.

The scientists hope the results of this study will help identify children with developmental disabilities that affect movement and coordination, such as cerebral palsy.

In a study published in the journal Proceedings of the National Academy of Sciences, experts from the University of Tokyo attached motion sensors to 12 newborns who were less than 10 days old, as well as 10 infants as young as three months old, to measure so-called spontaneous movements.

These random movements include kicks and wiggles without any external stimulation or apparent purpose—activities that begin in the womb as kicks before the baby is born.

The scientists then fed the data into a computer program that allowed them to analyze how the muscles of the entire body of the babies interacted with each other.

They found that spontaneous movement patterns helped develop the sensorimotor system, the scientific name for the body’s ability to control muscles for movement and coordination.

Lead author Professor Hoshinori Kanazawa, an expert in infant development, said this disproves previous research that suggested that infants develop their sensorimotor system only through repetitive movements with a specific purpose: “Typically, the development of the sensorimotor system depends on repeated sensorimotor interactions which means that the more you do the same action, the more likely you are to learn and remember it. However, our results implied that infants develop their own sensorimotor system based on exploratory behavior or curiosity, so they don’t just repeat the same action.”

In addition to knowledge about infant development, further research on random movements could help establish what is normal.

Professor Kanazawa suggested that, in theory, this could help identify children with developmental disabilities earlier: “My main research goal is to understand the underlying mechanisms of early motor development and find knowledge that will help promote child development.”

The scientists hope to conduct further research into how random infant movements affect specific movements such as walking and stretching later in life.