How to Fix a Flat Spot on Your Baby’s Head

Most flat spots on a baby’s head are a form of positional plagiocephaly, and they respond well to a combination of repositioning, supervised tummy time, and, in moderate-to-severe cases, helmet therapy. The condition became far more common after the “Back to Sleep” campaign reduced SIDS deaths by encouraging supine sleeping, and the good news is that it is almost always treatable without surgery. But the approach that works best depends on how old your baby is, how pronounced the flattening is, and whether an underlying neck issue is contributing.

What Causes the Flat Spot

A newborn’s skull is soft and pliable by design. The bones haven’t fused yet, which is what allows the head to pass through the birth canal and the brain to grow rapidly in the first year. That same softness means external pressure can reshape the skull. When a baby consistently rests with the same part of the head against a firm surface, that area flattens over time. The flattening is usually on one side of the back of the head (plagiocephaly) or across the entire back (brachycephaly).

The single biggest contributor is limited head mobility in early infancy. Research has identified cervical imbalance, often linked to congenital muscular torticollis (a tightness in one of the neck muscles), as a major driver. When a baby’s neck muscles favor one side, the infant naturally rests with the head turned that way, concentrating pressure on the same spot night after night.¹ Spending extended time in infant seats, bouncers, rockers, and swings can compound the problem. A study measuring infant body position in commercial products found that babies sitting in these devices had their heads and necks flexed significantly compared to lying on a flat surface, increasing the time the same area of the skull bears pressure.²

Making Sure It Is Positional, Not Structural

Before jumping into treatment, your pediatrician needs to rule out craniosynostosis, a condition where one or more skull sutures fuse prematurely. The distinction matters enormously because craniosynostosis typically requires surgery, while positional plagiocephaly does not.³

There is a practical way to tell the two apart even at home. In positional plagiocephaly, the head takes on a parallelogram shape: the ear on the flat side shifts forward, and the forehead on that same side may bulge slightly. The whole side of the head looks like it has been gently pushed forward. In craniosynostosis, the shape is more trapezoidal, and the ear on the affected side shifts backward and downward rather than forward.⁴ A quick check is to place a finger in each of your baby’s ears and look down from above. If the ear on the flat side sits noticeably farther forward, that strongly suggests a positional cause. Your doctor can confirm with a physical exam and, if needed, imaging.

Repositioning and Tummy Time

For mild cases caught early, repositioning is the first-line treatment and often the only one needed. The goal is to take pressure off the flat area. When your baby is awake and you’re watching, alternate which direction you lay them down. Switch which end of the crib you place their head at, since babies tend to turn toward the room. During feeding, alternate which arm you use. Move interesting things (a mobile, a window, your face) to the side your baby tends to look away from, giving them a reason to turn their head in the new direction. These strategies work best in the first few months when the skull is most malleable, but research suggests that cranial molding deformities generally improve with repositioning combined with natural skull growth, especially when addressed early.⁵

Tummy time is the other key tool. Placing your baby on their stomach while awake and supervised takes all pressure off the back of the head and simultaneously builds neck and shoulder strength. A systematic review found that tummy time was associated with better gross motor development and a reduction in brachycephaly (the bilateral, back-of-head flattening pattern).⁶ The same review found the evidence for tummy time specifically preventing unilateral plagiocephaly was less clear-cut, which makes sense: if torticollis is the underlying cause, tummy time alone won’t fix the neck tightness driving the head preference. But it remains a core part of any treatment plan because it reduces overall contact time on the flat surface and strengthens the muscles your baby needs to move their head freely.

Start with short sessions after your baby comes home from the hospital, even just a few minutes several times a day. Many babies protest at first. Lying down face-to-face with your baby during tummy time or placing a rolled towel under their chest to prop them slightly can make it more tolerable. The total amount matters more than any single session’s length.

When Physical Therapy Is Needed

If your baby has torticollis contributing to their head preference, repositioning alone won’t solve the problem because the neck muscle imbalance keeps pulling the head back to the same position. Pediatric physical therapy targets the tight sternocleidomastoid muscle through gentle stretching, guided range-of-motion exercises, and activities that encourage your baby to turn toward the non-preferred side. A study of infants with torticollis found that physical therapy episodes averaged about seven visits over roughly two months, and about three-quarters of the babies met their treatment goals in that time.⁷

Your pediatrician or a pediatric physical therapist can assess whether torticollis is present. Signs to watch for include a persistent head tilt to one side, difficulty turning the head in one direction, or a preference for looking one way during sleep. The earlier therapy begins, the easier the muscle responds. Left untreated, torticollis not only perpetuates the flat spot but can limit motor development on one side of the body.

Helmet Therapy and When It Makes Sense

Cranial orthoses, commonly called helmets or bands, work by providing a snug fit over the prominent areas of the skull while leaving space over the flat area. As the brain grows, it expands into the open space, gradually rounding out the head shape. Helmets don’t squeeze the skull into shape; they redirect growth.

The evidence shows that helmet therapy produces meaningful improvement, especially for moderate-to-severe cases. One study of infants with moderate to severe plagiocephaly found that roughly 84% achieved treatment success, with the greatest improvements in babies who started before nine months and had good compliance wearing the helmet.⁸ The theme across the research is consistent: earlier is better. A study tracking the rate of correction found that babies who started treatment youngest corrected at about 0.93 mm per week, while those who started later corrected at roughly half that speed. The treatment also took longer the older the baby was at initiation.⁹ Research on treatment started at four months versus later found especially strong results at that early age, with the benefit declining as infants approached eight months and beyond.¹⁰

Most specialists recommend starting helmeting between four and six months for the best outcomes and consider it much less effective after twelve months, once the skull sutures begin to firm up and brain growth slows. Babies typically wear the helmet 23 hours a day, removing it only for bathing. Treatment duration varies but commonly runs three to five months depending on severity and age at the start.

Do Helmets Actually Beat Doing Nothing?

This is where the debate gets interesting. Both helmeted babies and babies managed with repositioning alone tend to improve, because the skull naturally becomes more rounded as the child grows. The question is whether helmets improve things faster or more completely than repositioning.

A recent systematic review and meta-analysis pooling data from multiple studies found that the reduction in cranial asymmetry was substantially greater in the helmet group compared to both natural history and repositioning groups.¹¹ A head-to-head comparison of helmet therapy versus conservative management found that about two-thirds of helmeted infants achieved a reduction in severity level, compared to about 42% of conservatively managed infants.¹² However, when measured as the monthly rate of improvement in asymmetry, the two groups were comparable, suggesting that helmets may produce a larger total correction partly because treatment is sustained and consistent rather than because the monthly pace of change is dramatically different.

Helmet therapy also showed more favorable outcomes in correcting both cranial and ear asymmetry in moderate-to-severe cases without compromising head growth.¹³ The general consensus among craniofacial specialists is that helmets are most clearly justified for moderate-to-severe asymmetry that hasn’t responded to a couple of months of repositioning, particularly in the four-to-eight-month window. For mild cases, especially in young infants, conservative management and watchful waiting are reasonable first steps.

How Much Does the Head Correct on Its Own?

One of the most reassuring studies followed children with positional skull deformation out to age three. Head shape in affected children became substantially more rounded and symmetric over time, with the most dramatic improvement happening between infancy and 18 months. However, the study also found that about 86% of children who had positional plagiocephaly or brachycephaly as infants still showed some measurable difference from unaffected children at 36 months, with those differences ranging from one to two standard deviations on skull shape measurements.¹⁴ Even children who had milder flattening as infants continued to show subtle differences compared to unaffected children. Improvement continued after 18 months, but at a slower pace.

What this means practically is that most flat spots get noticeably better on their own, but “better” doesn’t always mean “gone.” Whether a residual difference matters is partly a question of severity and partly a personal judgment call. Once a child has hair covering the back of their head, mild residual asymmetry is typically invisible. More significant residual flattening can affect how glasses and helmets (bicycle helmets, sport helmets) sit later on.

Facial Asymmetry and Why It Matters Beyond Cosmetics

Flat spots are not just about the back of the head. Three-dimensional CT analysis has shown that infants with positional plagiocephaly also develop facial asymmetry, with the severity of facial differences tracking closely with the severity of the cranial asymmetry. Shortening of the jawbone on the affected side was particularly significant, along with nasal asymmetry.¹⁵ In very severe cases, deformation extends to the base of the skull and is accompanied by a noticeable shift in ear position.¹⁶

This is one reason clinicians take moderate-to-severe plagiocephaly seriously rather than dismissing it as purely cosmetic. Jaw asymmetry can affect bite alignment, and ear-position differences can make fitting eyeglasses difficult. Helmet therapy has been shown to improve facial symmetry alongside cranial symmetry, which is an additional argument for treatment in more pronounced cases.

The Connection Between Flat Spots and Developmental Delays

Parents sometimes hear that plagiocephaly is linked to developmental delays and worry that the flat spot is harming their child’s brain. The picture is more nuanced than that. A systematic review of 19 studies found a positive association between plagiocephaly and developmental delay in the majority of papers, with motor delay being the most commonly affected area.¹⁷ But most researchers describe plagiocephaly as a marker of elevated risk, not a cause. The same factors that contribute to flattening, such as torticollis limiting head movement and reduced time in active positions, can independently slow motor development.

A serial assessment study that tracked infants with plagiocephaly over time found that about 30% had at least one developmental delay at initial evaluation, rising to 42% at a three-month follow-up, but dropping back to about 23% by the twelve-month follow-up when the children were on average 17 months old. The delays were predominantly in gross motor skills and largely resolved as the children aged.¹⁸ The takeaway is not panic but rather vigilance: if your baby has a flat spot, it’s worth keeping tabs on motor milestones and asking about early intervention if anything seems slow. The flat spot itself isn’t squeezing the brain. But the underlying movement limitations that caused the flat spot can also slow physical development, and addressing both at the same time makes sense.

Getting a Proper Measurement

How do you know if your baby’s flat spot is mild, moderate, or severe? Your eye can tell you something is off, but it’s not great at grading severity. Clinicians use several tools, from simple calipers that measure the diagonal difference across the skull to 3D photography systems that capture the entire head shape. A review of diagnostic methods found that caliper-based measurements and a technique called plagiocephalometry were more reliable than visual assessment alone.¹⁹ Many helmet providers use 3D scanning technology, which produces a detailed map of your baby’s head and generates exact numbers for asymmetry. These measurements help determine whether a helmet is warranted and serve as a baseline to track progress.

The key number you’ll encounter is the cranial vault asymmetry index, sometimes abbreviated CVAI. This is essentially the percentage difference between the two diagonal measurements of the skull. Values under about 3.5% are generally considered normal, while values above 6-7% indicate moderate asymmetry, and above 10-12% is severe. If your pediatrician is on the fence about a referral, asking for an objective measurement can help you both make a more informed decision.

Insurance, Cost, and Access

Helmets are not cheap. Out-of-pocket costs commonly run into the thousands of dollars, and insurance coverage varies widely. A study of Massachusetts health insurance claims found that the average copay for helmet treatment was essentially zero for publicly insured patients but about $560 for those with private insurance. About 4% of private insurance claims were fully denied, compared to about 1% of public insurance claims.²⁰ The same study revealed a significant disparity in access: patients in medically underserved areas were less likely to receive helmet treatment, and the overall rate of helmeting had declined over the study period.

If your insurance denies the claim, it’s worth appealing with documentation from your provider, including objective measurements showing moderate-to-severe asymmetry and evidence that conservative repositioning was tried first. Some orthotics companies offer payment plans, and a few charitable organizations help cover costs for families who can’t afford treatment. The timing pressure adds urgency to these logistical hurdles, since waiting months for an insurance appeal while the treatment window narrows is a real frustration parents face.

Managing Parental Anxiety

Noticing a flat spot on your baby’s head can trigger a cascade of worry, and the internet doesn’t always help. A study analyzing online discussion boards about cranial shape found that more than 70% of parents’ emotional posts expressed negative emotions, with anxiety about the diagnosis being the most common concern, followed by frustration with how doctors responded to their worries.²¹ Many parents feel dismissed when a provider says “it’ll round out” without offering specifics, while others spiral after encountering worst-case scenarios online.

A few things can help ground you. First, positional plagiocephaly is extremely common and genuinely does improve with time, particularly before 18 months. Second, if you’re concerned enough to research the topic, you’re already the kind of parent who will follow through on repositioning, tummy time, and therapy if needed. Third, a flat spot is not a sign of neglect or something you did wrong. Safe sleep positioning is the right call for preventing SIDS, and plagiocephaly is a manageable trade-off. Finally, requesting objective measurements gives you numbers to track rather than relying on anxious visual comparisons week to week.

How Infant Skull Bones Differ From Ours

The reason any of this works, whether it’s repositioning, tummy time, or helmets, is that an infant’s skull is fundamentally different from an adult’s. The cranial bones aren’t fused; they’re separated by fibrous sutures and soft spots (fontanelles) that allow the skull to flex during birth and accommodate the rapidly expanding brain. This same plasticity that makes the skull vulnerable to flattening is what allows it to be reshaped. By around 18 months, the anterior fontanelle closes in most babies, and the skull bones begin to thicken and stiffen. Brain growth, which is fastest in the first year, slows as well. These two changes together are why the window for both natural correction and helmet effectiveness narrows after the first birthday. Historical and archaeological evidence actually confirms just how moldable infant skulls are: in multiple ancient cultures, prolonged low-intensity pressure applied from birth through the first two to four years of life was used to deliberately reshape children’s skulls into culturally desired forms.²² The modern challenge is much simpler than that; you’re just working with nature to undo an accidental version of the same process.