Flat Head (Positional Plagiocephaly)
The short answer
Flat spots on a baby's head are very common and almost always caused by positioning, not a structural problem. Most positional flat spots improve significantly with simple repositioning strategies and supervised tummy time.
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By Age
What to expect by age
0-2 months
Newborn heads are soft and mouldable by design. A slight flattening from sleeping position is extremely common at this age. Alternating which direction your baby faces during sleep can help prevent a flat spot from developing.
2-4 months
This is when positional flattening is often most noticeable, because babies spend a lot of time on their backs (which is the safest sleep position). Increasing supervised tummy time and varying your baby's head position during awake periods is the main approach.
4-8 months
As babies gain head control and start rolling, many flat spots begin to improve on their own. If a flat spot is moderate to severe, this is the window when a helmet (cranial orthosis) is most effective, typically starting around 4-6 months.
8-12 months
Most mild to moderate flat spots have improved considerably by now as your baby spends more time upright. Helmet therapy is less effective after about 12 months because skull growth slows. Hair growth also helps conceal any remaining asymmetry.
12 months+
The skull continues to remodel gradually throughout early childhood. Many parents who were worried at 3-4 months find the shape has rounded out significantly by this age. Residual mild asymmetry is common in the general population and rarely causes any issues.
What Should You Do?
When to take action
- A mild flat spot on one side of the head, especially if your baby has a preferred sleeping position
- The flat area is improving with repositioning and increased tummy time
- Your baby's ears appear roughly symmetrical and the forehead is not noticeably pushed forward on one side
- Your baby moves their head freely in both directions when awake
- Your baby was born with some moulding from the birth canal that is gradually resolving
- The flat spot seems to be getting worse despite repositioning efforts
- Your baby strongly prefers turning their head to one side and resists turning the other way, which may suggest torticollis
- You notice the ear on the flat side appears pushed forward, or the forehead is more prominent on one side
- The flat spot is still significant at 4 months and you want to discuss whether a helmet evaluation makes sense
- You notice a ridge or raised line along the top or side of your baby's skull, which could indicate craniosynostosis rather than positional flattening
- The head shape appears to be worsening rapidly or is accompanied by other developmental concerns
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.