Low Muscle Tone in Arms (Hypotonia)
Medically reviewed by Dr. Sarah Chen, MD, FAAP · Board-Certified Pediatrician
Content reviewed against published AAP, NIH, CDC guidelines
Last reviewed:
Your baby's physical development is unique, and concerns about low muscle tone in arms (hypotonia), here is what you need to know.
The short answer
Low muscle tone in the arms means your baby's arms may feel floppy or offer less resistance than expected when you move them. While some babies naturally have lower muscle tone that improves with time and practice, significant or persistent low tone in the arms can affect reaching, grasping, and tummy time skills. Your pediatrician can assess whether your baby's tone is within the normal range or whether a referral for physical or occupational therapy would be helpful.
Key takeaways
- Low muscle tone in the arms means your baby's arms may feel floppy or offer less resistance than expected when you move them. While some babies naturally have lower muscle tone that improves with time and practice, significant or persistent low tone in the arms can affect reaching, grasping, and tummy time skills. Your pediatrician can assess whether your baby's tone is within the normal range or whether a referral for physical or occupational therapy would be helpful.
- Usually normal when: Your baby has slightly lower tone than other babies but is meeting developmental milestones within the expected timeframes.
- Call your doctor if: Your baby's arms have become progressively floppier over time rather than getting stronger, or your baby has lost arm movement they previously had.
- Varies by age — see the age-by-age breakdown below
“Supervised tummy time is recommended daily from the time the baby comes home from the hospital to help prevent flat head syndrome and to strengthen neck and shoulder muscles.”
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What Parents Should Know
According to AAP, NIH, CDC guidelines, low muscle tone in the arms means your baby's arms may feel floppy or offer less resistance than expected when you move them. While some babies naturally have lower muscle tone that improves with time and practice, significant or persistent low tone in the arms can affect reaching, grasping, and tummy time skills. Your pediatrician can assess whether your baby's tone is within the normal range or whether a referral for physical or occupational therapy would be helpful. At 0-3 months, newborns typically hold their arms in a flexed position close to their body and offer some resistance when you gently extend their limbs. A baby with low arm tone may let their arms rest loosely at their sides and offer little resistance when moved. Some degree of variation is normal, and premature babies often have lower tone initially. If your baby's arms seem significantly floppy and they have difficulty with feeding or show very little arm movement, bring this to your pediatrician's attention. It is generally considered normal when your baby has slightly lower tone than other babies but is meeting developmental milestones within the expected timeframes. However, you should contact your pediatrician promptly if your baby's arms have become progressively floppier over time rather than getting stronger, or your baby has lost arm movement they previously had.
Normal vs. Concerning
By Age
What to expect by age
0-3 months
Newborns typically hold their arms in a flexed position close to their body and offer some resistance when you gently extend their limbs. A baby with low arm tone may let their arms rest loosely at their sides and offer little resistance when moved. Some degree of variation is normal, and premature babies often have lower tone initially. If your baby's arms seem significantly floppy and they have difficulty with feeding or show very little arm movement, bring this to your pediatrician's attention.
3-6 months
By this age, babies should be reaching for objects, bringing their hands together at midline, and starting to bear weight on their forearms during tummy time. Low arm tone can make these activities more difficult. You may notice your baby tires quickly during tummy time, has trouble reaching for and holding toys, or seems to use their arms less than expected. Physical therapy can be very effective at this stage to build strength.
6-12 months
Babies are now transferring objects between hands, feeding themselves finger foods, and bearing weight through their arms for crawling. Low arm tone may slow progress in these areas. Your baby may crawl with a modified pattern or prefer to scoot rather than bear weight through their arms. An evaluation can help determine the best approach to support your baby's upper body development.
1-3 years
Toddlers with low arm tone may have difficulty with activities like throwing a ball, climbing playground equipment, pushing riding toys, or using utensils. They may tire more quickly during activities that require arm strength. Occupational therapy can help build functional arm strength through play-based activities. Many children with mild low tone make excellent progress with consistent support.
What to Tell Your Pediatrician
- Describe when you first noticed low muscle tone in arms (hypotonia) and how it has changed over time.
- Note your baby's current age and which age-specific patterns you are seeing.
- Mention if your baby's arms feel notably floppy and they have difficulty bearing weight on their arms during tummy time by 4 months.
- Mention if your baby seems to avoid using their arms for reaching, grasping, or weight bearing, and this is affecting their development.
- Bring a list of any questions or observations you want to discuss at the appointment.
What Should You Do?
When to take action
- Your baby has slightly lower tone than other babies but is meeting developmental milestones within the expected timeframes.
- Your premature baby has lower arm tone that is gradually improving as they grow.
- Your baby's arms feel a bit relaxed, but they are actively reaching for objects, bearing weight during tummy time, and using their hands appropriately for their age.
- There is a family history of being very flexible or "double-jointed," and your baby is otherwise developing well.
- Your baby's arms feel notably floppy and they have difficulty bearing weight on their arms during tummy time by 4 months.
- Your baby seems to avoid using their arms for reaching, grasping, or weight bearing, and this is affecting their development.
- You notice that your baby's arm tone is significantly different on one side compared to the other.
- Your baby's arms have become progressively floppier over time rather than getting stronger, or your baby has lost arm movement they previously had.
- Your baby has severely floppy arms combined with difficulty feeding, breathing problems, or overall low alertness.
What You Can Do at Home
- Keep track of when you notice low muscle tone in arms (hypotonia) — noting the time of day, duration, and any triggers can help your pediatrician.
- Remember that your baby has slightly lower tone than other babies but is meeting developmental milestones within the expected timeframes — this is generally within the range of normal.
- At 0-3 months, focus on observation rather than intervention unless your pediatrician advises otherwise.
- Provide plenty of supervised floor time and tummy time to support your baby's physical development.
- While monitoring at home, seek immediate care if your baby's arms have become progressively floppier over time rather than getting stronger, or your baby has lost arm movement they previously had.
Related Resources
Milestone Checklists by Age
Track your baby's developmental milestones from birth to 5 years with age-specific checklists.
Month-by-Month Development
Detailed monthly development guides from birth through 24 months.
When to Call the Doctor
General guide on when to call the pediatrician, visit urgent care, or go to the ER.
Frequently asked questions
Is low muscle tone in arms (hypotonia) normal?
When should I call the doctor about low muscle tone in arms (hypotonia)?
When is low muscle tone in arms (hypotonia) normal?
What causes low muscle tone in arms (hypotonia)?
What should I mention to my pediatrician about low muscle tone in arms (hypotonia)?
Is low muscle tone in arms (hypotonia) normal at 0-3 months?
Is low muscle tone in arms (hypotonia) normal at 3-6 months?
Should I go to the ER for low muscle tone in arms (hypotonia)?
Does low muscle tone in arms (hypotonia) go away on its own?
References
Doctor Visit Checklist
Bring this checklist to your next pediatrician visit to discuss Low Muscle Tone in Arms (Hypotonia).
Things to mention
- Describe when you first noticed low muscle tone in arms (hypotonia) and how it has changed over time.
- Note your baby's current age and which age-specific patterns you are seeing.
- Mention if your baby's arms feel notably floppy and they have difficulty bearing weight on their arms during tummy time by 4 months.
- Mention if your baby seems to avoid using their arms for reaching, grasping, or weight bearing, and this is affecting their development.
- Bring a list of any questions or observations you want to discuss at the appointment.
Observations to share
- Your baby's arms feel notably floppy and they have difficulty bearing weight on their arms during tummy time by 4 months.
- Your baby seems to avoid using their arms for reaching, grasping, or weight bearing, and this is affecting their development.
- You notice that your baby's arm tone is significantly different on one side compared to the other.
Urgent signs to report immediately
- Your baby's arms have become progressively floppier over time rather than getting stronger, or your baby has lost arm movement they previously had.
- Your baby has severely floppy arms combined with difficulty feeding, breathing problems, or overall low alertness.
My notes
From ismybabyalright.com — free, evidence-based baby health guides
All content follows our editorial policy and is reviewed against published clinical guidelines.
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Related Resources
Bottom line
Most cases of low muscle tone in arms (hypotonia) are normal. Talk to your pediatrician if your baby's arms have become progressively floppier over time rather than getting stronger, or your baby has lost arm movement they previously had.
Trust your instincts. If something feels wrong, reach out to your pediatrician. Worrying about your baby means you care — that is a good thing.
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