Most baby bald spots are completely normal and temporary. The majority of infants lose some hair during their first six months of life, and the back of the head is the most common place it shows up. The two biggest culprits are natural hormonal shifts after birth and simple friction from lying on their backs. In nearly all cases, the hair grows back on its own within a few months.
Hormonal Hair Shedding After Birth
While in the womb, your baby was exposed to high levels of your hormones, which kept their hair in an active growth phase. After birth, those hormone levels drop sharply, and many of your baby’s hair follicles shift into a resting phase all at once. This is the same process that causes postpartum hair loss in new mothers.
During this resting phase, the hair stops growing for one to six months, with three months being the average. When the follicles eventually restart their growth cycle, the new hair pushes the old strand out, and that’s when you notice the shedding. This means the hair loss you’re seeing at three or four months actually started as an invisible process weeks earlier. The shedding itself typically lasts less than six months, and for many babies it resolves much faster than that. The hair that grows back may be a different color or texture than the original newborn hair.
Friction From Sleep Position
If the bald spot is specifically on the back of your baby’s head, friction is the most likely cause. Babies between 3 and 6 months old are especially prone to this because they spend so much time on their backs (as they should for safe sleep) but are constantly turning their heads side to side. Every head turn rubs fine baby hair against the crib mattress, playpen, activity mat, or infant seat. Over weeks, this repeated friction wears the hair away in a visible patch. The American Academy of Pediatrics notes that a flat spot is also more likely when a baby’s head position isn’t alternated between right and left during sleep.
This type of hair loss, sometimes called friction alopecia, resolves on its own once your baby starts sitting up and spending less time on their back. You don’t need any special treatment.
How Tummy Time Helps
Supervised tummy time is the single best thing you can do to reduce friction on the back of your baby’s head. The AAP recommends 30 minutes of tummy time per day, which you can break into several short sessions if your baby fusses. By two months of age, aim for at least 15 to 30 minutes total daily. Beyond protecting hair, tummy time helps round out any flat spots on the skull and builds shoulder and neck strength that your baby needs for crawling later on. Always stay in the room and keep your eyes on your baby during tummy time, since there’s a suffocation risk until they can roll over independently.
You can also alternate which direction your baby’s head faces in the crib from night to night. Some parents switch the head and foot positions so the baby naturally turns toward the room’s light or activity from a different side.
Cradle Cap and Hair Loss
Cradle cap is a form of skin irritation that causes thick, crusty, or oily patches on a baby’s scalp. On lighter skin, these patches tend to look yellow and greasy. On darker skin, they appear as patchy scaling or thick crusts with flaky white or yellow scales. Cradle cap itself isn’t painful or itchy, but the thick scales can sometimes trap hair, and when the scales eventually flake off, hair may come with them. This creates small areas of thinning that fill back in once the cradle cap clears.
Gentle washing with a mild baby shampoo and softly brushing the scales with a soft-bristled brush usually helps. If the patches are stubborn, your pediatrician can suggest additional approaches.
Less Common Causes Worth Knowing
Fungal Infection
Ringworm of the scalp (a fungal infection, not an actual worm) is uncommon in infants but possible. The most common sign is scaling that can look a lot like cradle cap, which makes it easy to miss. Other clues include redness, patchy hair thinning, and areas where the hair appears broken rather than simply absent. The scaling tends to be more irregular and may be accompanied by mild inflammation. Because it mimics cradle cap so closely, any scalp rash that doesn’t improve with normal cradle cap care is worth having checked.
Alopecia Areata
This autoimmune condition causes one or more round, smooth bald patches with no flaking, redness, or scaling on the skin underneath. It’s distinctly different from friction bald spots because the skin looks perfectly smooth and the patches tend to be very well-defined circles or ovals. Alopecia areata is rare in infants but can occur in young children. If you notice a completely smooth, coin-shaped bald patch that doesn’t match the typical back-of-head friction pattern, it’s a good reason to bring it up with your pediatrician.
What the Bald Spot Looks Like Matters
The appearance of the bald spot itself tells you a lot about what’s going on. Here’s a quick comparison:
- Back of the head, diffuse thinning: Almost certainly friction from sleeping. Resolves when baby sits up more.
- All-over thinning or shedding: Likely normal hormonal hair loss. Resolves by 6 to 12 months.
- Thick, crusty, or flaky patches with some thinning: Probably cradle cap. Responds to gentle washing and brushing.
- Red, scaly, or inflamed patches with broken hairs: Could be a fungal infection. Needs a pediatrician’s evaluation.
- Perfectly smooth, round patch with no skin changes: Possible alopecia areata. Worth a medical look.
Normal baby hair loss doesn’t come with redness, pus, swelling, or broken-off hair shafts. If the bald spot has any of those features, or if it’s spreading rather than staying the same size, that’s a sign something beyond normal shedding or friction is going on. Similarly, if your baby seems to be scratching or bothered by the area, the skin itself may need attention rather than just the hair.