Updated: 2 days ago
You are bathing your baby and you notice it: one side of the back of their head is a little flatter than the other. Or the whole back seems wider and shorter than you expected. Your mind goes straight to the internet. And then the worry sets in.
Take a breath. This is one of the most common things we see in newborns and young infants. The medical term is positional plagiocephaly, a flat spot on one side, or brachycephaly, flattening across the whole back of the head. According to the Canadian Paediatric Society, plagiocephaly peaks at around 4 months of age and affects up to 19.7 percent of infants at that stage. Most cases improve. And there is a lot you can do right now at home.
19.7%
Of infants show some flattening at around 4 months of age
10-15min
Supervised tummy time, three or more times a day, from birth
4-8mo
The window when helmet therapy works best, if it is recommended
Why does this happen?
The Back to Sleep campaign dramatically reduced SIDS deaths in Canada. But placing babies on their backs for sleep also meant more pressure on the back of the head during those long stretches of rest. Research has since documented a significant increase in positional head flattening as a result.
A newborn skull is soft and malleable by design. This allows the brain to grow rapidly in the first year of life. But that same softness means sustained pressure in one area, even from sleeping, can leave a flat spot. Other contributing factors include:
A preferred head position due to tight neck muscles, known as torticollis
Prematurity, which means more time spent lying in one position in the NICU
Multiple births, where space in the uterus creates positional constraints
Extended time in car seats, swings and bouncers that keep the head in one position
IMPORTANT DISTINCTION
Positional plagiocephaly is caused by external pressure and is different from craniosynostosis, where the skull bones fuse too early. The two can look similar. The CPS recommends that all infants with plagiocephaly be assessed to rule out craniosynostosis and torticollis. If you are unsure, ask your care provider.
What you can do at home right now
The CPS and Health Canada recommend supervised tummy time for every awake baby: at least 10 to 15 minutes, three or more times per day. This is the single most important thing you can do to prevent and improve positional head flattening.
If your baby dislikes tummy time at first, that is completely normal. Here is how to build their tolerance:
Start with just 1 to 2 minutes right after a diaper change, when they are alert and comfortable
Get down on the floor at eye level to keep them engaged
Place a rolled-up towel under their chest to make the position easier while neck strength develops
Try tummy time on your chest or lap instead of the floor, which some babies tolerate better early on
Use toys, mirrors, or your face to give them something to lift toward
Build gradually, aiming for at least 30 minutes across the day by 3 to 4 months
Alongside tummy time, try these repositioning strategies:
Alternate which end of the crib you place your baby's head, to encourage them to look in different directions
Vary your carrying position, and use a carrier to take pressure off the back of the head
Limit time in car seats, swings and bouncers when not travelling
Encourage them to turn toward sounds, your voice, or toys on their less preferred side
When should you see someone?
The CPS recommends well-baby checks within the first week, and at 2 and 4 months. These visits are the right time to raise any concerns about head shape. But do not wait if you are worried. Earlier assessment leads to earlier action, and earlier action leads to better outcomes. Ask about a referral if:
The flat spot is not improving after 2 to 4 weeks of consistent repositioning and tummy time
Your baby consistently turns their head to one side and resists turning the other way
The flat spot is on one side only and seems to be getting more pronounced
Your baby is approaching 4 to 5 months and the asymmetry is still significant
You notice the ear on the flat side appearing pushed forward compared to the other
A NOTE ON TIMING
Helmet therapy started before 6 months of age produces better results in a shorter time. Babies who started treatment before 6 months averaged 3.45 months of treatment, compared with 4.18 months for those who started later. If a referral is recommended, do not delay.
What if repositioning is not enough?
For moderate to severe cases, or when repositioning has not produced improvement, a cranial remolding orthosis, commonly called a helmet, may be recommended. Helmets gently redirect skull growth, leaving space for the flat areas to fill out while applying light contact to the fuller areas.
A five-year follow-up study in the Journal of Craniofacial Surgery found clear improvement in cranial symmetry in children treated with individual molding helmets compared with those left untreated. In the untreated group, absolute cranial asymmetry did not significantly improve over five years. Helmets are most effective when started between 4 and 8 months of age, while the skull is still growing rapidly.
Side effects are generally minor. A multi-site Canadian study tracking 453 infants found that 87 percent of clinic visits had no significant issues to report. The most commonly noted effects were pressure marks and temporary redness, closely linked to fit quality. Well-fitted helmets, with regular follow-up and adjustments, dramatically reduce discomfort.
How SuperNurse helps
In those early weeks and months, it can be hard to know whether what you are seeing is mild and temporary, or something worth acting on. Our Licensed Nurses can come to your home and:
Assess your baby's head shape with a trained clinical eye and help you understand what you are looking at
Demonstrate tummy time techniques and positioning strategies tailored to your baby
Identify early signs of torticollis or neck tightness that may be contributing
Advise you on when to seek a referral and help you navigate next steps
Support consistent implementation of the positioning strategies that make the biggest difference
The earlier you act, the more options you have. That is true whether the answer is tummy time, physiotherapy, or a helmet referral. Our job is to make sure you have the right information at the right time.
WATCH
Repositioning and tummy time
A short demonstration of the repositioning and tummy time techniques described above.
SOURCES
Canadian Paediatric Society. Positional Plagiocephaly Practice Point.
CPS Caring for Kids. Preventing Flat Heads in Babies Who Sleep on Their Backs.
AboutKidsHealth, SickKids. Plagiocephaly: Flat Head Syndrome.
Matarazzo et al. Orthotic Treatment of Cranial Asymmetries: Early vs Late Intervention. Journal of Prosthetics and Orthotics. 2016.
Wilbrand et al. Treated vs Untreated Positional Head Deformity: 5-Year Follow-up. Journal of Craniofacial Surgery. 2016.
Graham and Wang. Side Effects of Cranial Remolding Orthoses: A Multi-Site Review. Journal of Craniofacial Surgery. 2022.
Kassandra DiCosola, NP
Nurse Practitioner and co-founder of SuperNurse. Pediatric and NICU background, practising across Toronto and the GTA.