The most effective way to keep your baby’s head round is to vary the position of their head throughout the day, starting from birth. Infant skulls are soft and flexible by design, with open gaps between the bone plates that allow the brain to grow rapidly. That same softness means sustained pressure on one spot can create a flat area, a condition called positional plagiocephaly that affects roughly 6% of infants. The good news: most flat spots are preventable with a few simple daily habits.
Why Baby Skulls Flatten So Easily
A newborn’s skull isn’t a single solid bone. It’s made of several plates connected by flexible seams called sutures, with two soft spots (fontanelles) where the plates haven’t yet met. The rear soft spot typically closes by 1 to 2 months, while the larger one on top stays open until roughly 7 to 19 months. During that window, the skull can be reshaped by any consistent outside pressure.
The most common cause of flattening is simply keeping a baby’s head in the same position during sleep. Once a small flat area forms, the head naturally rolls toward that flat side because of gravity, which makes the flattening progressively worse. This cycle tends to accelerate during the first five to six months of life, when babies spend the most time on their backs and can’t yet reposition themselves easily.
Some babies are at higher risk. Boys develop flat spots at nearly twice the rate of girls (7.3% vs. 4.2%), and premature infants are affected at roughly double the overall rate (11.8% vs. 5.3% for full-term babies). First births, assisted deliveries, and multiple pregnancies also raise the likelihood.
Alternate Head Position Every Day
The simplest prevention strategy is changing which direction your baby faces in the crib each day. One day, place your baby with their head at the head of the crib. The next day, flip their orientation so their head is at the foot. Babies are naturally drawn to look toward light, sounds, or the open room, so alternating their position ensures they rotate which side of the head bears weight during sleep.
You can also place a mobile on the room-facing side of the crib to encourage your baby to turn their head away from the mattress-contact spot. During daytime naps in a bassinet, simply alternate which end you lay them down from. The key principle is that no single area of the skull gets hours of uninterrupted pressure night after night.
Make Tummy Time a Daily Habit
Tummy time is the single best tool for both preventing flat spots and building the neck and shoulder strength your baby needs to eventually hold their head up and roll over. You can start just a day or two after birth. In the early weeks, aim for two or three sessions a day lasting three to five minutes each. By around two months, the goal is 15 to 30 minutes of total tummy time spread across the day.
Not every baby loves tummy time at first. Lying on your chest counts, and so does draping your baby belly-down across your lap. A rolled towel tucked under the chest can make floor time more comfortable for very young infants. The point is simply to get your baby off the back of their head during waking hours.
Limit Time in Car Seats and Bouncers
Car seats, swings, bouncers, and infant rockers all press against the same spot on the back of the skull. They’re fine for their intended purpose, but babies who spend long stretches in these devices outside of car travel accumulate extra pressure time. When your baby is awake and supervised, holding them upright, wearing them in a carrier, or placing them on a play mat gives the skull a break from that contact.
Check for Neck Tightness
A condition called congenital muscular torticollis is one of the strongest risk factors for head flattening. It happens when a muscle on one side of the neck is shortened or tightened, causing the baby to consistently tilt or turn their head to one side. If your baby strongly prefers looking one direction, resists turning the other way, or always tilts their head to the same shoulder, that pattern deserves attention.
Untreated torticollis doesn’t just cause a flat spot. Over time it can lead to facial asymmetry, limited head movement, and compensatory spinal curvature. The condition is typically identified through a physical exam and sometimes an ultrasound of the neck muscle. When caught early, gentle stretching exercises and physical therapy are highly effective at restoring full range of motion, which in turn allows the skull to round out naturally.
Skip the Head-Shaping Pillows
Products marketed to shape a baby’s head, including sleep positioners, wedges, and special pillows, are not only unproven but dangerous. The FDA has documented infant deaths linked to sleep positioners over the years. Babies can roll into these products and suffocate, or become trapped between the positioner and the side of a crib or bassinet. The FDA warns parents not to use infant positioners at all, regardless of the claims on the packaging. No product currently on the market has been cleared or approved to prevent flat head syndrome.
A firm, flat mattress with a fitted sheet and nothing else in the sleep space remains the safest setup.
When Flat Spots Need More Help
Most mild flat spots improve on their own once babies gain enough strength to move their heads freely and start spending more time sitting up. If repositioning and tummy time haven’t improved the shape by three to four months, or if the asymmetry is moderate to severe, a pediatrician may refer you for evaluation of a cranial remolding helmet. These helmets are typically fitted between three and seven months of age, when the skull is still growing rapidly enough to respond to gentle, sustained redirection.
The helmet works by leaving space over the flat area while gently guiding growth away from the rounded side. Babies usually wear it 23 hours a day for two to six months, depending on severity. Earlier treatment tends to produce better results because the skull becomes less moldable as the fontanelles close.
Flat Spot vs. Something More Serious
Positional flattening is by far the most common cause of an unusual head shape, but a rare condition called craniosynostosis, where one of the skull’s seams fuses too early, can also change head shape. The two look different on examination. Positional plagiocephaly creates a parallelogram shape when viewed from above: the back of the head is flat on one side, and the forehead and ear on the same side may shift slightly forward. Craniosynostosis creates a more trapezoidal or wedge-shaped skull and may involve a noticeable ridge along a suture line or an unusually firm or absent soft spot.
Craniosynostosis requires surgical treatment, while positional flattening does not. If you notice a bony ridge running along your baby’s skull or feel that a soft spot has closed unusually early, bring it up with your pediatrician. In most cases, a physical exam is enough to tell the difference.