Low Muscle Tone (Hypotonia)
The short answer
Low muscle tone means your baby's muscles feel less firm or their body feels "floppy" when you hold them. While it can sometimes indicate an underlying condition, many babies with mildly low tone do very well with support and strengthening activities.
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By Age
What to expect by age
0-2 months
All newborns have relatively low tone compared to older babies, and they naturally curl into a flexed position. Premature babies especially may feel floppier than full-term babies. Head lag when gently pulling your baby from lying to sitting is normal at this age, though they should show some effort to keep their head in line.
2-4 months
Babies are developing head control and should be starting to hold their head steadily when supported upright. During tummy time, they should be beginning to lift their head and push up on their forearms. If your baby seems unable to make progress with head lifting or feels unusually floppy, it is worth mentioning to your doctor.
4-6 months
By now, babies typically have good head control and are working on sitting with support. Babies with low tone may need more practice and encouragement during tummy time and supported sitting. Some babies with mild low tone begin to "catch up" around this age as they build strength.
6-9 months
Most babies are sitting independently and some are beginning to crawl. Babies with low muscle tone may reach these milestones a bit later, which is often manageable with physiotherapy support. Your doctor can help assess whether the tone difference is mild and isolated or part of a broader pattern.
9-12 months
Babies with benign low tone are often making good progress by this point, especially if they have had support from a physiotherapist. They may pull to stand and cruise a little later than average. Ongoing gentle strengthening through play continues to be helpful.
What Should You Do?
When to take action
- Your baby feels a bit "softer" than other babies but is still meeting motor milestones within a reasonable range
- Your premature baby has lower tone that is gradually improving as they grow
- Your baby has mild low tone but is making steady progress with head control, rolling, and sitting
- There is a family pattern of being more flexible or "double-jointed," and your baby is developing well overall
- Your baby seems noticeably floppier than other babies their age and is slow to develop head control
- Your baby has difficulty with tummy time even with lots of practice and support, and does not seem to be building strength
- Motor milestones like rolling, sitting, and reaching seem significantly delayed alongside the low tone
- Your baby tires very quickly during physical activities like tummy time or supported sitting
- Your baby feels suddenly more floppy than usual, seems less responsive, or has a significant change in their tone or alertness
- Your baby has difficulty feeding, a weak cry, and very low muscle tone, particularly in the newborn period
- Your baby has low tone combined with breathing difficulties or failure to thrive
Sources
Related Resources
Trust your instincts. If something feels wrong, reach out to your pediatrician.
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Related Physical Concerns
My Baby Seems to Use One Side More Than the Other
Babies should use both sides of their body fairly equally during the first 18 months of life. While slight preferences can be normal, a consistent pattern of favoring one side - using one arm much more than the other, crawling with one leg dragging, or turning the head predominantly one way - should always be discussed with your pediatrician. Early identification of asymmetry leads to the best outcomes.
My Baby Only Army Crawls
Army crawling (also called commando crawling) is a completely valid and normal way for babies to move. Many babies army crawl for weeks or even months before transitioning to hands-and-knees crawling, and some skip hands-and-knees crawling entirely. What matters is that your baby is independently mobile and exploring their environment.
One Side of My Baby's Body Moves Differently
Babies should generally use both sides of their body equally. If one side consistently moves differently, is weaker, stiffer, or less coordinated, this warrants evaluation. Asymmetric movement can indicate hemiplegia (cerebral palsy affecting one side), brachial plexus injury, or other neurological conditions that benefit from early therapy.
My Baby Crawls Unevenly
While some variation in crawling patterns is normal, consistently favoring one side or dragging one limb while crawling warrants attention. Babies should use both arms and both legs relatively equally when crawling. Persistent asymmetry could indicate muscle tone differences, hip issues, or neurological concerns that benefit from early evaluation.
My Baby Still Has the Fencing Reflex (Persistent ATNR)
The asymmetric tonic neck reflex (ATNR, also called the fencing reflex) causes your baby to extend the arm on the side they are looking toward. It should integrate between 4-6 months. If the ATNR persists strongly beyond 6 months, it can interfere with bringing hands to midline, bilateral hand use, and rolling. Evaluation is recommended.
Signs of Ataxia in Babies and Toddlers
Ataxia refers to wobbly, uncoordinated movements that result from problems with the cerebellum (the brain's coordination center). Signs include an unsteady, wide-based gait, difficulty with precise hand movements, and intention tremor (shaking that worsens when reaching for something). If you notice these signs, evaluation by a pediatric neurologist is important.