A flat spot on a baby’s head is a common concern for parents, often developing in the first few months of life. This phenomenon is largely due to the recommended “Back to Sleep” campaign for Sudden Infant Death Syndrome (SIDS) prevention, resulting from prolonged pressure on the soft, malleable infant skull. While back sleeping is a non-negotiable safety measure, it has increased the prevalence of positional head shape changes. These flat spots, known as deformational or positional plagiocephaly and brachycephaly, are generally cosmetic and do not affect brain development. The primary question is whether these changes will resolve on their own as the baby grows and becomes more mobile.
Understanding Positional Skull Deformities
Positional skull deformities occur because a newborn’s skull plates are flexible and not yet fully fused, allowing the head to mold under continuous external pressure. The two main types are distinguished by the location and symmetry of the flattening. Plagiocephaly involves an asymmetrical flattening, typically on one side of the back of the head, which can lead to a parallelogram shape when viewed from above. This flattening may also cause the ear, forehead, and cheek on the affected side to shift slightly forward.
Brachycephaly presents as a symmetrical flattening across the entire back of the head, causing the skull to appear disproportionately wide and short. Both conditions are caused by external forces, usually from extended periods spent lying on a flat surface, such as during sleep or in devices like car seats and swings. These positional changes are a benign condition, unlike craniosynostosis, where the skull sutures fuse prematurely.
The Natural Course of Head Shape Correction
Mild positional flattening frequently improves naturally without specialized intervention as the infant develops. This natural correction occurs because of the rapid growth of the infant’s brain and skull in the first few months of life. As the brain expands, it pushes against the skull, encouraging the flattened areas to round out, provided the external pressure is relieved.
Self-correction is strongly linked to the infant’s motor development, particularly the ability to gain head and neck control and to sit up unassisted. Once a baby can actively move their head and spends less time resting on the flattened area, the head shape gradually begins to normalize. This window of opportunity is time-sensitive, as the skull bones begin to harden and become less malleable after about six months of age.
Moderate to severe cases, or those that persist past six months, are less likely to resolve completely without active intervention. While some improvement occurs as the child becomes more mobile, a noticeable degree of flattening may remain if no steps are taken to relieve the pressure. Predicting which mild cases will fully correct can be difficult, so parents are encouraged to implement active repositioning strategies immediately upon noticing a flat spot.
Active Repositioning and Environmental Adjustments
Active repositioning is the first and most practical line of defense against positional skull deformities, focusing on shifting the pressure point away from the flattened area. This involves using the baby’s environment to encourage them to turn their head voluntarily to the non-flattened side. For example, parents can alternate the direction the baby faces in the crib each night so the baby is encouraged to look toward the door or other interesting stimuli.
“Tummy Time” is a crucial component, as it completely removes pressure from the back of the head while strengthening the neck and shoulder muscles. This supervised, awake time on the stomach should be integrated into the baby’s daily routine, beginning as early as a few weeks of age and gradually increasing in duration. Parents should also limit the time the baby spends in “containers” like car seats, swings, and bouncers outside of necessary transport, since these devices maintain constant pressure on the back of the skull.
During feeding and holding, parents should consciously alternate the side they use to carry the baby. For a baby with plagiocephaly, the goal is to encourage the head to rest on the fuller, rounded side, allowing the flat area to be suspended and grow. These small, consistent changes can significantly influence the head’s shape during the period of fastest growth.
Medical Assessment and Corrective Devices
Parents should consult a pediatrician if the flattening seems to be worsening, if there is severe asymmetry, or if the baby consistently prefers turning or tilting their head to one side, which may indicate torticollis (tight neck muscles). The pediatrician’s first task is to rule out craniosynostosis, a rare condition where one or more of the skull’s growth plates fuse prematurely. Craniosynostosis is typically present at birth and requires surgical intervention, while positional flattening develops later and is benign.
If the positional deformity is moderate to severe and has not improved significantly with repositioning by four to six months of age, a cranial orthosis, commonly known as helmet therapy, may be recommended. The custom-fitted helmet works by applying gentle, constant pressure to the prominent areas of the skull while leaving room for the flattened areas to grow. This capitalizes on the baby’s natural, rapid head growth to guide the skull into a more symmetrical shape.
Helmet therapy is most effective when started between four and six months because this is when the head is growing most quickly; treatment typically lasts for about three to six months. Treatment for any related torticollis, often involving physical therapy to stretch and strengthen the neck muscles, is frequently pursued alongside helmeting or repositioning. This ensures the baby can move their head freely in all directions.