Plagiocephaly, the flattening of one side of an infant’s skull, is largely preventable through simple daily habits that vary where pressure falls on your baby’s head. Since the “Back to Sleep” campaign began in 1992, the incidence of positional skull flattening has risen to affect up to 20% of infants, with one study tracking prevalence climbing from 5% to 46% by age 7 months. The good news: because this flattening is caused by external pressure rather than a bone disorder, most cases can be avoided with consistent repositioning during sleep, feeding, and play.
Why Flat Spots Develop
An infant’s skull bones are soft and separated by flexible sutures, which is what allows the head to pass through the birth canal. That same softness makes the skull vulnerable to pressure in the weeks and months after birth. When a baby rests with the same part of the head against a flat surface repeatedly, that area gradually flattens. Once a flat spot forms, it gets worse on its own: the baby’s head naturally rolls toward the flat side under gravity, increasing pressure on exactly the spot that’s already affected. This self-reinforcing cycle is why flattening typically worsens during the first five to six months of life if nothing changes.
Back sleeping is the single most important thing you can do to reduce the risk of SIDS, and that recommendation should never be compromised. Prevention isn’t about changing sleep position. It’s about varying which direction your baby’s head faces while still sleeping on the back.
Alternate Your Baby’s Orientation in the Crib
The simplest prevention strategy is changing which end of the crib you place your baby’s head. One night, lay your baby with the head at the top of the crib. The next night, place the head at the foot. Babies naturally turn toward light, sound, and activity in the room, so alternating orientation means they’ll turn their head to opposite sides on different nights. This distributes pressure evenly across the skull.
You can reinforce this by making the room-facing side of the crib more interesting. Position a mobile on that side, or place the crib so your baby has to look away from any existing flat spot to see you or the open room. Keep the wall side plain and unstimulating. These small environmental cues guide your baby’s natural head-turning reflex without you needing to physically reposition them while they sleep.
Build Up Tummy Time Starting Day One
Supervised tummy time is one of the most effective tools for preventing flat spots because it takes all pressure off the back of the skull. The American Academy of Pediatrics recommends starting the day your baby comes home from the hospital with two to three short sessions of three to five minutes each. By seven weeks, the goal is 15 to 30 minutes of total tummy time per day.
Many newborns protest tummy time at first. Getting down on the floor face-to-face with your baby, using a rolled towel under the chest for support, or placing your baby on your chest while you recline can all make it more tolerable. Tummy time also builds the neck and shoulder strength your baby needs to eventually turn the head freely during sleep, which itself helps prevent one-sided flattening.
Vary Positions During Feeding and Diaper Changes
Feeding time adds up to hours each day, and many parents default to holding their baby in the same arm every time. If you’re bottle feeding, switch arms at each feeding so your baby’s head rests against alternating sides. Breastfeeding naturally alternates sides, but if your baby has a preferred head position, pay attention to whether one breast consistently puts pressure on the same spot.
Diaper changes are another opportunity. If your baby tends to look in one direction, stand on the opposite side of the changing table so they turn toward you. These moments are brief individually, but they happen many times a day and collectively make a real difference in how evenly pressure is distributed.
Limit Time in Car Seats, Swings, and Bouncers
Car seats, infant swings, bouncers, and other “containers” all press the back of your baby’s head against a firm, curved surface. The average baby spends almost six hours per day in these devices, which experts say is far too much. The AAP suggests limiting container time to necessary car travel plus one additional hour or less per day.
When your baby isn’t in the car, choose holding, babywearing, or floor time over leaving them in the car seat carrier. If you do use a swing or bouncer, keep sessions short and alternate with time on the floor or in your arms where the head moves freely.
Watch for Neck Tightness
Congenital muscular torticollis, a tightness in one of the neck muscles, is the single biggest risk factor for plagiocephaly. It causes a baby to hold the head tilted to one side and rotated to the other, locking pressure onto the same part of the skull. About 41% of babies diagnosed with torticollis also develop plagiocephaly.
Signs to look for include a strong preference for turning the head to one side, difficulty turning to the other side, tilting of the head, and a visible or palpable firmness on one side of the neck. If you notice any of these, early physical therapy has a high success rate for restoring full range of motion. Identifying torticollis early, ideally in the first few weeks, allows treatment to begin before significant flattening develops.
Know the Timeline
The first six months are the critical window. Skull bones are most malleable during this period, which means flattening happens fastest but also responds best to repositioning. Most mild cases improve substantially with consistent repositioning alone, and further improvement continues as babies begin sitting up independently and spending less time on their backs.
For more severe cases that don’t respond to repositioning, cranial remolding helmets work best when started between five and six months of age. Delaying helmet therapy past this window significantly reduces its effectiveness, so early recognition matters. If you’re doing everything right and still notice worsening asymmetry by three to four months, raising it with your pediatrician gives you the most options.
Which Babies Are at Higher Risk
Some babies are more vulnerable to flat spots from the start. Risk factors include being a firstborn, premature birth, assisted delivery (vacuum or forceps), multiple pregnancy (twins or triplets), and being male. Babies born with any of these factors benefit even more from early, consistent repositioning habits. If your baby spent time in the NICU with limited position changes, beginning prevention strategies as soon as you’re home is especially worthwhile.