Plagiocephaly (Flat Head)
A common and usually cosmetic condition with a clear path forward
What Happened
Your baby has been diagnosed with plagiocephaly, which means one area of the head has become flattened. This most often happens because babies spend a lot of time on their backs (as they should - back sleeping prevents SIDS). The pressure from lying in one position causes the soft, malleable skull bones to flatten. This is called positional or deformational plagiocephaly, and it is extremely common, affecting up to 47% of infants at some point. It is almost always cosmetic and does not affect brain development. In rare cases, a flat-looking head can be caused by craniosynostosis, where skull bones fuse too early - your pediatrician can tell the difference with a physical exam.
Key Facts
- Positional plagiocephaly is very common. Studies show it affects up to 47% of babies at 7–12 weeks of age, though most cases are mild.
- It is cosmetic. Positional plagiocephaly does not put pressure on the brain and does not cause developmental problems.
- The difference between positional plagiocephaly and craniosynostosis is important. Your pediatrician can usually tell them apart by examining your baby's head shape and feeling the sutures (joints between skull bones).
- Craniosynostosis is rare (about 1 in 2,000–2,500 births) and requires surgical evaluation. Positional plagiocephaly does not.
- Helmets (cranial orthoses) work best when started between 4 and 12 months of age, during the period of fastest head growth.
- Many mild to moderate cases improve on their own with repositioning, especially once a baby starts sitting up independently.
What to Expect
- Your pediatrician may refer you to a specialist (pediatric neurosurgeon or craniofacial clinic) to confirm the diagnosis and rule out craniosynostosis.
- If the flattening is mild, your doctor will likely recommend repositioning strategies and monitoring over time.
- If the flattening is moderate to severe and your baby is in the 4–12 month window, a helmet may be recommended. Helmets are worn 23 hours per day for several months.
- Head shape continues to improve as your child grows, hair comes in, and the skull rounds out. By age 2–3, mild flattening is often not noticeable.
- You will not have done anything wrong. The "Back to Sleep" campaign saves lives. Flat spots are a manageable trade-off for safe sleep.
When to Worry
- If you notice a ridge along any of the suture lines on your baby's head, mention it to your pediatrician - this can be a sign of craniosynostosis.
- If the flattening is getting worse despite repositioning efforts, ask about a helmet evaluation sooner rather than later, since the treatment window is time-sensitive.
- If your baby strongly prefers turning their head to one side and resists looking the other way, they may have torticollis (tight neck muscles), which often accompanies plagiocephaly and benefits from physical therapy.
- If your baby's forehead or face appears asymmetric (one side bulging forward), bring this up with your doctor.
Your Action Plan
- Increase supervised tummy time when your baby is awake. Aim for 30–60 minutes of total tummy time per day, spread across multiple sessions. This strengthens neck muscles and reduces time spent on the flat spot.
- Alternate the direction your baby faces in the crib. Babies tend to look toward the room or doorway, so switch which end of the crib the head is at.
- During feeding, alternate which arm you hold your baby in to encourage head turning in both directions.
- Limit time in car seats, bouncers, and swings when your baby is not in a vehicle. These all put pressure on the back of the head.
- If torticollis is present, ask for a referral to pediatric physical therapy. Stretching exercises can improve neck range of motion, which helps the head shape improve.
- If a helmet is recommended, find a certified orthotist who specializes in pediatric cranial orthoses. The earlier within the 4–12 month window you start, the better the results.
- Continue safe sleep practices. Always place your baby on their back to sleep - head shape is not a reason to change sleep position.
Sources
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.
Task Force on Sudden Infant Death Syndrome. SIDS and other sleep-related infant deaths: Updated 2016 recommendations for a safe infant sleeping environment. Pediatrics. 2016;138(5):e20162938.
Safe Sleep for Babies. CDC Infant Health.