Newborn care

Baby Flat Head (Plagiocephaly): Causes, Repositioning, and When It Matters

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Flat spots on baby's head are usually positional — caused by time in one position — and often improve with supervised tummy time and repositioning. Brain development is not affected. Persistent cases may be evaluated for a helmet or for a tight neck muscle.

Last updated: July 2026History

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Why flat spots happen

A newborn's skull bones are not fused — they are designed to be flexible to allow passage through the birth canal and to accommodate rapid brain growth in the first year. This same flexibility means that sustained pressure on one area can cause that area to flatten. Babies who spend a lot of time on their backs (which is the correct, safe sleep position) and who have a preference for turning the head to one side are especially likely to develop a flat spot.

An important connection: an estimated 85% of infants with torticollis (a tight neck muscle that limits head rotation) develop positional skull deformities 1. Prematurity, multiples, and limited space in the womb can also be contributing factors. Positional plagiocephaly is purely a shape issue — it does not affect brain development or intelligence 1.

Tummy time: the most important thing families can do

Supervised tummy time — placing the baby on their stomach while awake and an adult is watching — is the cornerstone of both preventing and improving flat spots. The AAP recommends that infants have at least 30 minutes of tummy time spread throughout each day 2, working up gradually from shorter sessions starting from birth.

Tummy time:

  • Relieves pressure from the back of the head
  • Builds neck, shoulder, and core strength the baby will need for rolling and crawling
  • Encourages the baby to lift and turn the head, which helps even out the shape

Many newborns strongly dislike tummy time at first; starting with short sessions (even two to three minutes at a time, several times a day) on a firm surface is a reasonable starting point. Placing the baby chest-to-chest on a parent's chest also counts as tummy time.

Repositioning strategies

In addition to tummy time, repositioning the baby when they are awake and supervised can reduce pressure on the flat area 2:

  • Alternate which end of the crib the baby's head is toward; babies often turn to look toward the room's activity, so changing the orientation shifts which side they turn to.
  • When holding or carrying the baby, vary which arm the baby rests on.
  • Limit time in bouncers, swings, and car seats during the day (outside of necessary travel) — these put the same pressure on the back of the head that lying on a flat surface does.

Safe sleep guidelines still require that the baby sleep on their back on a firm, flat surface without soft bedding — repositioning applies to awake supervised time.

When a provider might look more closely

Pediatricians typically monitor head shape at well visits. A few things may prompt closer evaluation 1:

  • A tight neck muscle (torticollis): If the baby consistently turns the head only one direction and resists turning the other way, a tight neck muscle may be contributing. Physical therapy is commonly recommended in that case.
  • Asymmetry of the ears or face: Significant flattening can shift the position of one ear forward relative to the other. A provider can assess whether the degree of asymmetry is within the range that tends to self-correct.
  • A helmet (cranial orthosis): For some babies whose head shape is not improving with repositioning by around four to six months, a custom-molded helmet worn most of the day can gently redirect growth. The window for helmeting is generally in the first year while the skull is still growing rapidly. Whether it is appropriate is a discussion between the family and the pediatrician or a specialist.

Common questions

Positional plagiocephaly is a shape issue, not a brain issue. The flattening is of the skull, not the brain, and does not affect brain development or cognitive outcomes. That said, if a provider suspects the skull bones are fusing too early (craniosynostosis, which is a different and much less common condition), they will evaluate further — a provider can distinguish these on examination.

Two months is an excellent time to start repositioning and tummy time — the skull is still very moldable and there is substantial time for improvement before the skull starts to firm up. Most improvement is seen between two and four months of age with consistent effort.

The AAP recommends working toward at least 30 minutes of total supervised tummy time per day, built up gradually from shorter sessions starting at birth. Any tummy time is beneficial; more is generally better as long as the baby is supervised and awake.

The first few months are the period of greatest malleability. Without repositioning, a flat spot may deepen during this window. However, as babies gain the ability to roll and sit independently — typically around four to six months — they naturally spend less time in one position, and many flat spots improve on their own once babies are more mobile.

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When to get care right away

  • —The baby consistently cannot turn the head in one direction — possible tight neck muscle (torticollis) that benefits from early physical therapy
  • —The flat area is accompanied by ridging or raised edges along the seams of the skull — this could indicate premature fusion of skull bones (craniosynostosis), a different condition that needs prompt evaluation
  • —Head shape is asymmetric and worsening rapidly despite repositioning efforts

This article is general health information and does not constitute medical advice or a diagnosis. A pediatrician can assess head shape directly and recommend next steps specific to the baby.

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References

  1. 1.American Academy of Pediatrics (HealthyChildren.org) (2023). When a Baby's Head is Misshapen: Positional Skull Deformities. HealthyChildren.org. link ✓85% of torticollis cases develop positional skull deformities; plagiocephaly is purely cosmetic with no effect on brain development; physical therapy and helmet indications
  2. 2.American Academy of Pediatrics (HealthyChildren.org) (2023). Back to Sleep, Tummy to Play. HealthyChildren.org. link ✓AAP recommendation for at least 30 minutes of supervised tummy time per day; repositioning strategies including alternating crib orientation and limiting time in swings and car seats

2 sources, numbered by first appearance. General health information, not medical advice. AI-assisted editorial content — every citation independently verified. Editorial policy

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