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Infants » Newborn Development

Four Month Old Arm Tremors

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Dear Susan:

My 4 month old son has some slight trembling in his right arm while it is in a certain position (parallel to his back and bent in a 90 degree angle). His arm function seems totally normal except for this occasional tremble. It only happens when his arm is in this special position and does not happen at any other time. My wife thinks he used to favor one arm a month ago, but he is now using both arms to the same degree. We had a doctor look at it and he said he would not have noticed it if we had not pointed it out. He didn’t  seem concerned, but did schedule us for an x-ray to see if there was any neurological damage at birth.

Here is my question: Is this a normal thing to happen and if not, should I be concerned with it? It only started happening two weeks ago after he recovered from a cold.


Dear Matthew

Thank you so much for visiting the website. As you know, without knowing your son, I can’t really address the slight tremor you detected. Your doctor needs to attend to any follow-up you may need, but I can give you general comments regarding 4 month olds and tremulous movements. They are entirely normal and reflexive in nature. Infants’ neurological systems between birth and seven months are often a bit immature depending on birth weight, gestational experiences in the womb, and a million other things. Think of your baby as protecting himself when he flails his arms out, or turns his head to watch his hands or put his fingers in his mouth. Arms and legs are often jerky and shaky. Your doctor can explain all the different reflexes from which your baby learns to self-regulate his actions. If he shows any facial tremors or any unwanted movements that make him cry or get upset, or interferes with his sucking, call your doctor and tell him about it. Tell him a lot; don’t be afraid to call and ask questions. Also, ask me any specific questions you want to.  That’s what I’m here for.


Susan H. Turben, Ph.D.

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