This Is Why Babies Tremble When They Aren't Cold Or Crying

It has nothing to do with the weather.

Ever notice your newborn's chin quiver without a tear in sight? Or maybe their legs tremble quickly making you wonder if they're cold. It's not just you, it's actually your baby's brain.

Within the first two years of life, your baby's brain and central nervous system undergo a lot of developmental change and maturation, Dr. Evan Lewis, pediatric neurologist and director of the Neurology Centre of Toronto, tells HuffPost Canada.

And for the first two months, baby's life is especially affected by these changes. "When a baby is born, his/her normal reflexes are immature resulting in them being overactive," Lewis explains. Trembling and quivering should come to a complete stop after this period.

Overactive reflexes can result in chin and lower lip quivering as well as jittery limbs multiple times a day. As the nervous system develops, inhibitory signals mature and jitteriness/tremors disappear.

Another factor that can cause newborn tremors is high levels of hormones like norepinephrine, which functions similarly to adrenaline. "These are released in response to the human body adapting to its new air-breathing world," Lewis says. The hormones have a stimulating effect which can manifest in tremors and uninhibited movements. Over time, these hormone levels decrease, which also puts an end to baby jitters.

Jitters and jerkiness can be caused by the same neurological changes, but Lewis says jerky movements are "slightly more worrisome than tremors or jitteriness."

Fast, brief, jerky movements can occur both singly or repetitively and are referred to as myoclonus — a muscle twitch followed by relaxation. Generally speaking, myoclonus is not harmful (hiccups are a form or myoclonus) but occasionally it can be so severe that it can limit a person's ability to eat, talk and walk, the National Institute of Neurological Disorders and Strokes reports.

If you notice your child making jerk-like movements, Lewis says you should try to stop them by restraining the jerking limb or provoking a different movement through a loud clap or by quickly moving the baby from one position to another. And don't worry too much about discomfort — the movements are generally not harmful and usually stop on their own.

If they don't, other tricks for stopping or preventing quivering are to slowly and gently bend the limb or put a finger or soother in the mouth.

If your child experiences myoclonus in their sleep, try waking up the child. "Benign Neonatal Sleep Myoclonus usually stops by four months of age," says Lewis.

Age isn't the only factor to consider when it comes to tremors — Lewis recommends consulting a doctor if jitters are excessive; they don't stop with intervention; are linked to eye rolling, sucking, chewing or tongue movements; or if your child appears unwell.

When consulting a doctor be sure to provide a complete pregnancy and family history. Newborns may also require a thorough neurological examination to rule out any abnormalities.

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