My Baby Seems to Use One Side More Than the Other
The short answer
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.
Parents everywhere have the same worry. You are doing the right thing by looking into it.
By Age
What to expect by age
0-3 months
Newborns may briefly prefer turning their head to one side, but their arm and leg movements should be fairly symmetric. If your baby consistently keeps one hand fisted while the other is open, or if one arm moves much less than the other, bring this to your pediatrician's attention. Torticollis (tight neck muscles causing a head-turn preference) is common and very treatable at this age.
4-6 months
By this age, babies should be using both hands to reach for and grasp toys and should kick both legs equally. If you notice your baby consistently reaching with only one hand, or if one leg seems stiffer or less active than the other, mention it to your doctor. These observations are valuable - parents are often the first to notice subtle asymmetries.
7-9 months
When crawling develops, watch for symmetry. Some babies have an "imperfect" crawl that still uses both sides, which is fine. But if your baby consistently drags one leg, uses one arm differently, or leans heavily to one side, an evaluation is important. Asymmetric crawling can sometimes indicate a difference in tone or strength between the two sides.
10-18 months
As your baby starts pulling up, cruising, and walking, symmetry becomes easier to observe. Both legs should bear weight equally, and your baby should use both hands during play. If one side is clearly weaker or less coordinated, a referral to a pediatric neurologist or physical therapist is recommended. Early intervention can make a significant difference.
What Should You Do?
When to take action
- Your baby occasionally prefers one hand for a specific activity but uses both hands well overall.
- Your baby has a slight head-turn preference in the first few weeks that is resolving with repositioning.
- Your baby crawls with a slightly asymmetric pattern but uses both arms and legs actively.
- Your toddler over 18 months is developing a natural hand preference - this is appropriate at that age.
- Your baby consistently uses one hand much more than the other before 18 months.
- Your baby turns their head strongly to one side and resists turning to the other.
- Your baby crawls with one leg dragging or tucked underneath while the other pushes.
- When your baby stands or walks, one leg seems stiffer, weaker, or positioned differently than the other.
- Your baby suddenly stops using one arm or leg after previously using both equally - acute onset of one-sided weakness is a medical emergency.
- One side of your baby's body seems consistently stiff or rigid while the other side moves normally.
- Your baby has asymmetric movement combined with seizure-like episodes, unusual eye movements, or changes in alertness.
Sources
Related Resources
Trust your instincts. If something feels wrong, reach out to your pediatrician.
Worrying about your baby means you care. That is a good thing.
Related Physical Concerns
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.
My Baby Walks on Hands and Feet
Bear walking, where a baby walks on their hands and feet with their bottom up in the air, is a normal movement pattern. It shows excellent upper body strength and coordination. Many babies bear walk as a transitional movement before walking upright, and it is not a cause for concern.