Babies do a lot of things that seem like a complete mystery to adults but are actually very intentional. For instance, you might be wondering why a baby shakes its head back and forth while sitting up or during tummy time. The reason is more relatable than you probably realize.
At first glance, it may seem like your baby has already mastered the art of defiantly telling you "no." Don't worry, you still have a little bit of time before that starts happening because this behavior isn't about communicating, it's about moving and having fun. "We usually see head shaking side to side when a baby is seeking movement sensation," Duke University Health's pediatric occupational therapist Lilie I Bonzani, OTR/L, and occupational therapist Mary Hart Macleod, OTR/L, tell Romper. They say that this type of behavior "may be seen when the baby is tired or irritable or in need of stimulation" of some kind.
Another reason they may be shaking their head? For fun. "This sort of imitative or stimulative head shaking is normal, and often you’ll see your infant smiling or laughing to indicate they’re enjoying it," pediatrician David L. Hill, MD, FAAP, explains in an email to Romper. This back-and-forth with you is a lot of fun for your baby, because it's also a new way of communicating and interacting with you. "You’ve been in constant communication since birth," says Dr. Hill, "but this is one of the most obvious signs that yes, you’re playing together."
Bonzani and Macleod explain that once babies start crawling, they are able to expel energy that way, so it's less likely their head shaking is about moving. However, babies start to crawl around nine-months-old, which is about the time Dr. Hill says imitation play starts to ramp up. So, your baby will continue to shake its head, but the purpose behind it will change.
Of course, there are caveats to this behavior. Bonzani and Macleod agree that when head shaking is "seen in combination with other developmental concerns such as gross motor delays, challenges with sleep, poor feeding development and behavior," it's a good idea to talk to the pediatrician to see if they recommend any monitoring or intervention with an occupational therapist. Additionally, a shaking head can signal something larger. "A very different sort of [head shaking] movement can indicate a seizure," explains Dr. Hill, "where the infant turns their head to one side or starts jerking uncontrollably." In this case, seek urgent medical attention.
Still, generally speaking, if your baby is shaking its head from side to side, it's perfectly normal and nothing to be concerned about. Well, for now at least. Once they do master communicating the defiant "no", head-shaking takes on an entirely different meaning (it's called the "terrible twos" for a reason).
Lilie L. Bonzani, OTR/L, Pediatric Occupational Therapist at Duke Unversity Health
Mary Hart Macleod, OTR/L, Occupational Therapist at Duke University Health
David L. Hill, M.D., FAAP, Spokesperson for the American Academy of Pediatrics & Author of Co-Parenting Through Separation and Divorce: Putting Your Children First