Flat Head Syndrome (Plagiocephaly) in Babies

Flat head syndrome is a flattening of part of a baby’s skull caused by pressure from lying in one position, before birth or in the first months of life. When one side of the back of the head is flat, it is called plagiocephaly; flat across the whole back is brachycephaly.¹ It is common: in one cohort of healthy full-term babies seen at their 2-month checkup, nearly half had some degree of it, and most cases were mild.² Positional flattening does not affect brain growth or intellectual development, and it is treated with changes in position, tummy time and, for some babies, physical therapy or a helmet, not surgery.³ Babies still sleep on their backs.⁴

What flat head syndrome is

A baby’s skull is made of soft, bony plates that have not yet fused, which lets the head pass through the birth canal and leaves room for the brain to grow in the first year. Steady pressure on one spot can reshape them.³ There are three common patterns:¹

• Plagiocephaly, the most common: the back of the head is flat on one side.
• Brachycephaly: flat across the whole back of the head, which can make the head look wide.
• Dolichocephaly: flat on the sides, so the head looks long from front to back.

Seen from above, a head with positional plagiocephaly often looks like a parallelogram: the flat side of the back, the ear on that side moved a little forward, and the forehead on that side more prominent.^3,8

Flattening became much more common after the early 1990s, when parents were first advised to put babies to sleep on their backs. The American Academy of Pediatrics (AAP) links the two, and is clear that healthy babies should still sleep on their backs, because back sleeping is associated with a drastic fall in sudden infant death syndrome.¹⁰

What causes a flat spot on a baby’s head

About one in five positional head-shape changes starts in the womb or the birth canal; more often it develops in the first 4 to 12 weeks of life, before a baby can move their own head much.³ The AAP lists these causes:³

• a preferred head position, sitting or sleeping with the head turned the same way;
• not enough tummy time while awake;
• being a twin or triplet, from cramped positions in the womb;
• prematurity, from lying flat in the hospital on softer bones;
• birth complications, including forceps or vacuum delivery;
• torticollis, a tight or imbalanced neck muscle. An estimated 85% of babies with torticollis have a positional skull deformity.

A baby’s visual preference can also keep the head turned one way, and once a flat spot exists, gravity tends to roll the head back onto it.¹ That is why the neck matters: a baby who cannot comfortably turn both ways keeps resting on the same spot, and treating the neck is part of treating the head.

Signs to look for at home

Parents are often the first to notice a flat spot.¹ The AAP suggests looking at your baby’s head after a bath, when the hair is wet:³

• the back of the head should be evenly round;
• the ears should be level and even;
• the width of the head and forehead should look balanced.

Also watch which way your baby looks when lying on their back. A baby with plagiocephaly may keep their head turned consistently to one side, and without intervention the flattening can worsen and shift the ear, forehead and jaw on that side forward.¹ If you notice any change or have a concern, mention it to your pediatrician.³

Flat head or craniosynostosis?

Craniosynostosis is the condition parents worry about: one or more of the skull’s seams (sutures) fuses too early. It is rare, in about 1 in every 2,000 US babies, and it is different in kind from a positional flat spot.⁸

• A positional flat spot gives the parallelogram shape, with the ear on the flat side pushed forward.⁸
• A fused suture may be felt as a ridge along the skull, and gives its own shapes: a long, narrow head; a forehead pinched at the sides; a forehead flattened on one side with a raised eyebrow; or, rarest, a ridge on the back of the head with a bump behind the ear.⁸

Your pediatrician tells the two apart.³ A neurosurgical guideline found that examining the baby is most often enough, that imaging is rarely necessary, and that a CT scan should not be used to diagnose plagiocephaly, though it may be needed to rule out craniosynostosis.⁹ The distinction matters because craniosynostosis usually needs surgery, and tummy time and helmets do not correct it on their own.⁸

Repositioning and tummy time

Changing how a baby spends their awake time is the first treatment, and the best prevention. What the AAP advises:^3,11

• Give supervised tummy time from the day your baby comes home: 3 to 5 minutes, 2 to 3 times a day, working up to 15 to 30 minutes a day by 7 weeks.¹¹
• Keep building toward about an hour a day, in several short sessions.³
• Limit time in car seats outside the car, bouncy seats, swings and other carriers, which all press on the back of the head.³
• Switch arms when you hold and feed your baby, and alternate which end of the crib you lay them down at, so they turn both ways toward you and the light.^3,11

Sleep does not change. Babies sleep on their backs, on a firm, flat surface that is not inclined.⁴ Infant head-shaping pillows are not safe: they make the sleep space less safe and may add to suffocation risk, and the FDA says there is no evidence they work.³

On its own, repositioning education gives some degree of correction in virtually all babies with positional plagiocephaly or brachycephaly, according to the neurosurgical guideline’s review.⁶

How physical therapy helps

A pediatric physical therapist works out what is causing the flattening and the best treatment for it, and refers on to another specialist where needed.¹ At the evaluation the therapist checks for torticollis and for motor skills delayed by poor head and neck control, and teaches you stretching and positioning to do at home; depending on severity, a baby may be seen weekly.³

The evidence favors starting it. The Congress of Neurological Surgeons guideline found physical therapy significantly more effective than repositioning education alone, and recommends physical therapy over any positioning device.^5,6 The American Physical Therapy Association advises that the sooner a family sees a physical therapist, the better the chance of improving the head shape.¹

Where the cause is a tight neck muscle, the treatment is the torticollis treatment, set out in the physical therapy guideline for congenital muscular torticollis.¹² Torticollis in babies covers it step by step, and physical therapy explains what a PT does across childhood.

Helmet therapy: who it is for

The AAP says a baby with moderate or severe flattening that has not responded to treatment by 5 or 6 months of age may benefit from a molding helmet, fitted by a specialist.³ A helmet only works while the skull is actively growing. It is usually worn about 23 hours a day for several months, and a baby who starts younger may need it for less time.¹³

How much a helmet adds is debated:

• The neurosurgical guideline found a substantial body of nonrandomized studies showing faster and greater improvement with a helmet than with conservative treatment, especially for severe flattening, though the right measurements and the right age window remain unsettled.¹⁴
• A randomized trial of 84 babies aged 5 to 6 months with moderate to severe flattening found the head shape at age two the same with or without a helmet; every parent in the helmet group reported at least one side effect.⁷

So a helmet is a decision to make with your pediatrician, weighing how severe the flattening is, your baby’s age and what has been tried. Surgery for positional flattening is considered only when every other option has been exhausted, and only after seeing a neurosurgeon or pediatric plastic surgeon who specializes in it.³

When to call the doctor

Tell your pediatrician about a flat spot when you notice it; APTA advises that a baby with an uneven posture or a flat spot be referred to a pediatric physical therapist as soon as it is noticed, without waiting for the next well visit.¹ Ask promptly if your baby:

• has a hard ridge you can feel along the skull, or a head that is long and narrow, or a forehead that is flat on one side with a raised eyebrow;⁸
• keeps their head tilted or turned to one side, or seems unable to turn it fully the other way;¹
• has flattening that is not improving with position changes.¹³

A ridge points toward craniosynostosis, which needs a specialist; the other two point toward a physical therapy evaluation.^3,8

Getting started: early intervention and finding a physical therapist

Your pediatrician may refer your baby to early intervention for a physical therapy evaluation.³ You can also refer your baby yourself: parents are named as a referral source under Part C of the Individuals with Disabilities Education Act, and the evaluation is free.¹⁵ Outside early intervention, every US state allows you to see a physical therapist directly in at least some circumstances, though your insurance may still ask for a referral.¹⁶

Look for a pediatric physical therapist, and ask about their experience treating babies with flat head syndrome before you book.¹ The physical therapy directory lists clinics by state and city, with each practice’s own description of who it treats; physical therapy for infants and toddlers covers what therapy looks like at this age.

Sources

1. American Physical Therapy Association. Physical therapy guide to flat head syndrome: plagiocephaly, brachycephaly, and dolichocephaly (ChoosePT). A baby with plagiocephaly “may prefer to keep their head turned consistently to one side”; it can result from a tight muscle (as with torticollis); “Physical therapists help determine the cause of the head flattening and the best treatment,” and “The sooner a family sees a physical therapist, the better the chances of improving or preventing further head shape deformities.” Checked October 6, 2026.
2. Mawji A, Vollman AR, Hatfield J, McNeil DA, Sauvé R. The incidence of positional plagiocephaly: a cohort study. Pediatrics. 2013;132(2):298–304. doi:10.1542/peds.2012-3438 (PMID 23837184). 440 healthy full-term infants assessed at 2-month well-child clinics in Calgary: 205 had some form of plagiocephaly, an incidence of 46.6% at 7 to 12 weeks; 78.3% of those were mild and 63.2% were on the right side.
3. American Academy of Pediatrics, Section on Neurological Surgery and Section on Plastic and Reconstructive Surgery. When a baby’s head is misshapen: positional skull deformities (HealthyChildren.org, updated November 3, 2022). About 20% occur in the womb or birth canal, “more often, it happens in the first 4 to 12 weeks of life”; causes include a preferred head position, not enough tummy time, twins or triplets, prematurity, birth complications and torticollis (“An estimated 85% of babies with torticollis … have a positional skull deformity”); “Positional skull deformities do not affect brain growth or intellectual development”; work up to an hour of tummy time a day in several short sessions; head-shaping pillows “are not safe”; a physical therapist checks for “delayed motor skills caused by poor head and neck control, and for torticollis”; helmet therapy where “moderate or severe head flattening … does not respond to treatment by 5 or 6 months of age.” Checked October 6, 2026.
4. Moon RY, Carlin RF, Hand I; Task Force on Sudden Infant Death Syndrome and the Committee on Fetus and Newborn. Sleep-related infant deaths: updated 2022 recommendations for reducing infant deaths in the sleep environment. Pediatrics. 2022;150(1):e2022057990. doi:10.1542/peds.2022-057990 (PMID 35726558). AAP policy statement: a safe sleep environment includes supine positioning on a firm, noninclined sleep surface.
5. Baird LC, Klimo P, Flannery AM, Bauer DF, Beier A, Durham S, et al. Congress of Neurological Surgeons systematic review and evidence-based guideline for the management of patients with positional plagiocephaly: the role of physical therapy. Neurosurgery. 2016;79(5):E630–E631. doi:10.1227/NEU.0000000000001429 (PMID 27776088). “Physical therapy is significantly more effective than repositioning education as a treatment for positional plagiocephaly”; physical therapy “must be recommended over the use of a positioning pillow.”
6. Klimo P, Lingo PR, Baird LC, Bauer DF, Beier A, Durham S, et al. Congress of Neurological Surgeons systematic review and evidence-based guideline on the management of patients with positional plagiocephaly: the role of repositioning. Neurosurgery. 2016;79(5):E627–E629. doi:10.1227/NEU.0000000000001428 (PMID 27759673). Repositioning education “is effective in affording some degree of correction in virtually all infants”; it was “inferior to a physical therapy program”; given the AAP’s warning against soft positioning pillows in the sleep environment, “the Task Force recommends physical therapy over any positioning device.”
7. van Wijk RM, van Vlimmeren LA, Groothuis-Oudshoorn CGM, Van der Ploeg CPB, IJzerman MJ, Boere-Boonekamp MM. Helmet therapy in infants with positional skull deformation: randomised controlled trial. BMJ. 2014;348:g2741. doi:10.1136/bmj.g2741 (PMID 24784879). 84 infants aged 5 to 6 months with moderate to severe deformation, without torticollis or craniosynostosis: the change in head shape at 24 months was equal with a helmet and without; full recovery 26% versus 23%; “All parents reported one or more side effects.”
8. Taub PJ; American Academy of Pediatrics Sections on Plastic Surgery and Neurological Surgery. Uneven head shape in babies: causes and treatment of craniosynostosis (HealthyChildren.org, updated August 31, 2020). “About 1 in every 2,000 U.S. babies is born with craniosynostosis”; the positional head is the “classic parallelogram shape”; sutures that fused too soon “may be felt as ridges”; tummy time and helmets “are not, in themselves, effective in correcting craniosynostosis,” which usually requires surgery. Checked October 6, 2026.
9. Mazzola C, Baird LC, Bauer DF, Beier A, Durham S, Klimo P, et al. Congress of Neurological Surgeons systematic review and evidence-based guideline for the diagnosis of patients with positional plagiocephaly: the role of imaging. Neurosurgery. 2016;79(5):E625–E626. doi:10.1227/NEU.0000000000001427 (PMID 27759672). “Clinical examination is most often sufficient to diagnose plagiocephaly”; imaging “is rarely necessary”; CT “should not be used to diagnose plagiocephaly, but it may be necessary to rule out craniosynostosis.”
10. Laughlin J, Luerssen TG, Dias MS; Committee on Practice and Ambulatory Medicine; Section on Neurological Surgery. Prevention and management of positional skull deformities in infants. Pediatrics. 2011;128(6):1236–1241. doi:10.1542/peds.2011-2220 (PMID 22123884). AAP clinical report: the rise in occipital flattening since the early 1990s is “likely attributable” to back sleeping; positional deformities are “generally benign, reversible” and do not require surgery, unlike craniosynostosis; healthy infants “should be placed down for sleep on their backs.”
11. American Academy of Pediatrics. Back to sleep, tummy to play: give your baby a safe, strong start (HealthyChildren.org). Tummy time is for babies “who are awake and being closely supervised”: 2 to 3 times a day for 3 to 5 minutes from the day the baby comes home, working up to “15 to 30 minutes each day by 7 weeks”; a flat spot “usually rounds out as they grow older and sit up”; alternate which end of the crib the baby’s feet go, and limit time in swings, bouncy chairs and car seats. Checked October 6, 2026.
12. Sargent B, Coulter C, Cannoy J, Kaplan SL. Physical therapy management of congenital muscular torticollis: a 2024 evidence-based clinical practice guideline from the American Physical Therapy Association Academy of Pediatric Physical Therapy. Pediatric Physical Therapy. 2024;36(4):370–421. doi:10.1097/PEP.0000000000001114 (PMID 39356257). Covers screening, referral, physical therapy examination and first-choice interventions for infants with torticollis.
13. American Academy of Pediatrics, Section on Neurological Surgery and Section on Plastic and Reconstructive Surgery. Baby helmet therapy: parent FAQs (HealthyChildren.org, updated August 31, 2020). Helmets must be worn while the skull is growing, and “three-fourths of brain growth happens by age 2”; prescribed where a moderate or severe deformity “doesn’t respond to changing positions”; “Babies usually wear their helmets for 23 hours each day”; a younger start “may wear the helmet for less time”; “Children may need to wear a helmet for several months.” Checked October 6, 2026.
14. Tamber MS, Nikas D, Beier A, Baird LC, Bauer DF, Durham S, et al. Congress of Neurological Surgeons systematic review and evidence-based guideline on the role of cranial molding orthosis (helmet) therapy for patients with positional plagiocephaly. Neurosurgery. 2016;79(5):E632–E633. doi:10.1227/NEU.0000000000001430 (PMID 27776089). Nonrandomized evidence shows “more significant and faster improvement” with a helmet than with conservative therapy, “especially if the deformity is severe”; the best measurement criteria and time window “remains elusive.”
15. Individuals with Disabilities Education Act, Part C, 34 CFR Part 303. Parents are named among the “primary referral sources”: §303.303(c)(3). Evaluation and assessment are “required functions that must be carried out at public expense, and for which no fees may be charged to parents”: §303.521(b)(2). Services are provided “to the maximum extent appropriate, in natural environments,” which “may include the home or community settings”: §§303.126 and 303.26. Text as published in the eCFR. Checked October 6, 2026.
16. American Physical Therapy Association. Direct access advocacy. “As of July 1, 2025, all 50 states, the District of Columbia, and the U.S. Virgin Islands have either provisional or unrestricted direct access to physical therapist services for evaluation and treatment,” though some provisions tied to treatment still apply. Checked October 6, 2026.

Medical disclaimer. This page is for general educational purposes and does not constitute medical advice, diagnosis, or treatment. Always consult your baby’s doctor about head shape. If you can feel a ridge along your baby’s skull, contact their doctor promptly.