A baby’s head is naturally moldable during the first year of life, and most mild flat spots can be corrected with simple changes to how you position your baby during sleep, play, and feeding. The skull bones don’t fully fuse until 12 to 18 months of age, which means there’s a real window to influence head shape without any medical intervention. For moderate to severe flattening, a cranial remolding helmet may be recommended, typically starting between 4 and 7 months of age for the best results.
Why Baby Heads Are So Moldable
An infant’s skull isn’t one solid piece of bone. It’s made up of several plates separated by flexible joints called sutures, with soft spots (fontanelles) at the intersections. This design exists for two reasons: it allows the head to compress slightly during birth so it can fit through the birth canal, and it gives the brain room to grow rapidly during the first year. Because these bones are separate and flexible, outside pressure from sleeping surfaces, car seats, or even positioning in the womb can create flat spots. The same flexibility that makes babies vulnerable to flattening also makes correction possible.
Types of Head Flattening
Not all flat spots look the same, and recognizing the pattern helps you understand what’s going on.
Positional plagiocephaly is the most common type. It creates a parallelogram shape when you look at your baby’s head from above: one side of the back of the head is flat, and the ear on that side may be pushed slightly forward. This is caused by external pressure, like always sleeping with the head turned the same direction.
Brachycephaly is a broad, short skull shape where the entire back of the head is flat. This happens when a baby spends a lot of time on their back without enough variation in position.
Scaphocephaly is a long, narrow head shape that can develop in premature babies who spend extended time lying on their sides in the NICU.
All three of these positional types are different from craniosynostosis, a condition where skull bones fuse too early. The distinction matters because craniosynostosis requires surgery, while positional flattening responds to repositioning and, in some cases, helmet therapy.
Repositioning Techniques That Work
For mild flattening, repositioning is the first and often only treatment needed. The goal is to take pressure off the flat area and encourage your baby to turn their head in different directions throughout the day.
- Alternate crib orientation. Switch which end of the crib you place your baby’s feet. Babies naturally turn toward light and activity, so changing their orientation encourages them to look in different directions, shifting pressure off the flat spot.
- Switch feeding sides. Breastfed babies naturally change sides, but if you bottle-feed, consciously alternate which arm you hold your baby in during feedings.
- Limit time in carriers and seats. Car seats, bouncy chairs, and swings all press against the back of the head. Use them when you need to, but don’t let them become default resting spots throughout the day.
- Supervised tummy time. This is the single most effective repositioning tool. It takes all pressure off the back of the head while strengthening neck and shoulder muscles.
You can start tummy time a day or two after birth. Begin with two or three sessions of 3 to 5 minutes each day. By around 2 months, aim for 15 to 30 minutes of total tummy time daily. Right after a diaper change or when your baby wakes from a nap are good moments to fit it in. Increase the duration as your baby gets stronger and more comfortable.
When Torticollis Is Part of the Problem
Many babies with positional flattening also have torticollis, a tightness in the neck muscles that makes them strongly prefer turning their head one direction. If your baby always looks to the right, the right side of the back of the head gets constant pressure, and a flat spot develops there. Fixing the flat spot without addressing the neck tightness won’t get you far.
A pediatrician or pediatric physical therapist can diagnose torticollis and teach you gentle stretching exercises to do at home. These typically involve slowly tilting the baby’s ear toward the opposite shoulder and turning the chin toward the tight side, holding each stretch for about 30 seconds, repeating 3 to 4 times per session, and doing this 4 to 5 times a day. The stretches are gentle and, when done consistently, most cases of torticollis resolve within a few months.
Cranial Remolding Helmets
If repositioning alone isn’t enough, or if the flattening is moderate to severe, your pediatrician may recommend a cranial remolding helmet (also called a cranial orthosis). These custom-fitted helmets work by leaving space where the skull needs to grow and applying gentle contact where it doesn’t, guiding growth into a more symmetrical shape.
Timing matters significantly. The FDA approves helmet therapy for babies between 3 and 18 months old, but outcomes are best when treatment starts between 4 and 7 months. Babies who begin earlier tend to wear the helmet for a shorter period and end up with less residual asymmetry. Starting after 10 or 11 months still helps, but progress is slower because skull growth is decelerating.
Severity is measured using tools like the Cranial Vault Asymmetry Index (CVAI). A score under 6.25 is considered mild, 6.25 to 8.75 is moderate, 8.75 to 11 is severe, and above 11 is very severe. Helmets are generally recommended for moderate cases and above, though doctors also consider them for milder cases diagnosed at an older age when there’s less time for repositioning to work. Your pediatrician may assess your baby’s head using calipers, photographs taken from above, or a 3D scan to get precise measurements.
Products to Avoid
The market is full of head-shaping pillows and infant sleep positioners marketed to parents worried about flat spots. The FDA warns against all of them. These products, which typically feature foam bolsters or wedges placed in the crib, have been linked to infant deaths from suffocation. Babies can roll into dangerous positions against the bolsters, scoot into gaps between the positioner and the crib wall, or end up face-down on the device. No infant sleep positioner has been cleared or approved by the FDA for preventing flat head syndrome or reducing SIDS risk. A firm, flat sleep surface with no extra items in the crib remains the safest setup.
How to Tell If Something More Serious Is Going On
Positional flattening is overwhelmingly the most common cause of an asymmetric head shape, but craniosynostosis, where one or more skull sutures fuse prematurely, can look similar at first glance. There are a few key differences to watch for.
Positional plagiocephaly creates a parallelogram-shaped head when viewed from above. Craniosynostosis involving the back of the skull creates a trapezoid shape instead. With craniosynostosis, you may also notice a hard ridge along a suture line when you run your fingers over your baby’s head, or a fontanelle that feels unusually firm or has closed earlier than expected. A bulge behind the ear on the affected side is another distinguishing sign.
Positional flattening tends to improve or at least stabilize as babies gain head control and spend less time in one position. Craniosynostosis typically gets progressively worse. If the asymmetry is worsening despite consistent repositioning, or if you feel a bony ridge along any suture line, your pediatrician can order imaging to check whether the sutures are open and flexible as they should be.