Why Do Babies Shake Their Arms?

Everyone on the planet (other than super villains) can agree babies are the cutest. Their chubby cheeks and tiny toes can melt you to the core, but babies have the cutest reflexes, too. When babies get happy or startled, they tend to wave their arms around and it's absolutely adorable. But have you ever wondered, why do babies shake their arms?

According to the University of Maryland Medical Center (UMMC), when babies shake their arms it is called the Moro Reflex, and it is an involuntary response that happens when your baby is startled by a loud noise, bright lights, or if their head falls back or bobbles abruptly. Swaddling your baby in a blanket can help in preventing your baby from waking herself after being startled by keeping her arms snug inside.

The UMMC noted that the Moro reflex, which can vary in intensity among babies, is seen during the baby's first few months, but what about when they are a little older? After about 3 to 4 months of age, when babies gain more control over their necks, head, and limbs, they will flail their arms in excitement, explained University of California's Secrets of Baby Behavior. Almost all babies at this age will wave their arms and legs at things and people that they want to play with, too, because they feel like they can finally start to reach out for and grasp things.

If your baby is shaking arms when they are startled or happy, it's a good sign. What to Expect noted that if your baby is not shaking their arms when startled, or you notice a change in their reflexes, you should call your pediatrician for evaluations, because it could be due to other underlying problems.

Ultimately, it's good to know that arm shaking is a completely normal part of your baby's developmental process. Just sit back, cuddle, and enjoy the quirky, adorable moments your baby brings you everyday.