Why Is My Baby Losing Hair? Understanding the Bald Patch on the Back of the Head

Every parent finds it eventually. A soft, thinning patch at the back of a small head, right where it rests all night. Here is what is actually going on, and what the research says about it.

It usually happens somewhere around the ten-week mark. You are changing a nappy, or lifting your baby out of the cot in that half-light before dawn, and your hand comes away with a few fine strands on it. Then you notice the patch. A smooth, pale stretch at the back of the head, exactly where they lie, and the obvious conclusion arrives immediately: something is rubbing it off.

It is the most natural conclusion in the world. It is also, according to the dermatology research, almost certainly wrong. And knowing why turns out to be far more reassuring than the usual advice.

In short

The bald patch at the back of your baby's head is a natural shed on a timetable set before birth, not something rubbed away by the cot. Baby hair follicles do not cycle at random the way an adult's do. They move in waves that run from the front of the head towards the back. The hair at the front is already shedding around the time of birth, and the hair at the back is the last wave to go, letting go together at roughly eight to twelve weeks. That timing is why the patch appears where it does. It regrows on its own, generally well inside the first year. When researchers went looking for the friction everyone blames, they did not find it.

What is actually happening up there

Hair grows in cycles. There is a growing phase, a brief transitional one, and a resting phase called telogen, at the end of which the hair releases and a new one pushes through behind it. In adults these cycles are staggered, which is why you shed somewhere between fifty and a hundred hairs a day and never notice a thing.

In a newborn they are not staggered. They run in waves across the scalp, and the wave at the back of the head is the last to arrive. Hair at the front and sides has often already begun its shed by the time your baby is born, and is quietly regrowing while you are still in those first blurred weeks. The hair at the crown and occiput is still in its growing phase at birth, holds on a little longer, and then releases all at once. What you are looking at, in other words, is not a patch that was worn away. It is a patch that was always going to go last.

The American Academy of Pediatrics puts it plainly: almost all babies will lose some, and possibly all, of their hair during the first few months, and some will lose more from the back of the head than elsewhere.

The interesting part is what researchers found when they went looking for the friction everyone assumes is responsible. In a 2005 study published in the European Journal of Pediatrics, Cutrone and Grimalt checked whether cases had risen since the Back to Sleep guidance moved a generation of babies onto their backs. Across 301 newborns, they had not. The authors concluded the loss is physiological, and that the pillow, so often blamed, only aids a shed that was already underway.

A 2011 study in Annals of Dermatology approached it from the other end. Kim and colleagues reviewed the records of 240 births and interviewed the parents of 193 infants, found the patch in around one in five, and reported no significant correlation with sleeping position at all. Their conclusion was that this is not an acquired condition but a physiological one, the result of a synchronised shed that begins before birth. The European Academy of Dermatology and Venereology uses the term transient neonatal hair loss in its own guidance for parents, for exactly this reason.

Which is a long way of saying: you did not cause it, and there is nothing to fix.

Week by week, roughly

Every baby runs to their own clock, and only the first of these windows is firmly pinned down in the literature. Treat it as a shape rather than a schedule.

Birth to about six weeks. Often nothing obvious. Some babies arrive with a full head of hair, some with almost none, and both are normal.

Around eight to twelve weeks. The shed becomes noticeable. Strands on the cot sheet, on your shoulder, in the bath water. The patch at the back appears or widens. This is the stage most parents start searching at two in the morning, and it is the one window the research is specific about.

Three to six months. The shed usually slows and regrowth begins, though new hair often comes through fine and pale and takes a while to read as hair at all. The patch can look unchanged for weeks while it is quietly filling in underneath.

Six to twelve months. Most babies show visible regrowth through this stretch. Once they are sitting, rolling and spending far less of the day flat on their backs, the back of the head catches up with the rest.

One thing that surprises almost everyone: the hair that grows back is often not the hair you started with. The American Academy of Pediatrics notes that most baby hair is replaced by mature hair in the first six months, and that its colour and texture may be quite different. Dark newborn hair growing back fair, or straight growing back with a kink in it, is ordinary.

When to mention it to someone

The normal newborn patch sits at the back of the head where it rests, blends gradually into the hair around it, and the skin underneath looks like ordinary skin. Have a chat with your Plunket nurse or GP if you notice any of the following.

Scaling, redness, broken skin or crusting on the scalp. Smooth, completely bare patches elsewhere on the head with sharp, well-defined edges. Hair loss that starts after six months rather than before. A patch that is still clearly bald at around twelve months. Hair that has been sparse or absent since birth and never really comes in, particularly alongside anything unusual about nails, teeth or sweating. Or simply anything else that seems off to you.

These are all uncommon, and they are also exactly the sort of thing a Well Child visit exists for. There is no need to wait for the next scheduled one if you are worried.

So does the cot sheet matter at all?

Not for the shed. That much the research settles.

What a sleep surface does touch is the hair that is already there, and the skin around it. A woven cotton sheet has texture, and a baby who turns their head from side to side for hours at a time will move fine hair across it a great many times. Anyone who has tried to comb out a matted patch behind a toddler's ear knows what mechanical friction does to hair over time. It works on skin too, which is why rubbed, reddened cheeks are such a familiar complaint in the early months.

Silk is a smoother surface than woven cotton. That is a property of the fibre and the weave rather than a promise about outcomes. Silk arrives as one long continuous filament, where cotton is spun from short staple fibres, so the finished cloth has far fewer protruding fibre ends for anything to catch on. It is the same reason silk feels the way it does against your own cheek.

What we will not tell you is that a silk sleep surface regrows hair, prevents the patch or shortens the shed. It does none of those things, and any brand that says otherwise is selling you something the evidence does not support. It is simply a gentler surface for the months while everything grows back.

A note on safe sleep, which matters more than any of this

Nothing in a cot should ever come before safe sleep. Follow the guidance from Whānau Āwhina Plunket and KidsHealth NZ: your baby sleeps on their back, on a firm flat mattress, in their own bed, with nothing loose near their face.

If you use any fitted layer over the mattress, including ours, it must be pulled taut with the fastening secured, and it should not be used at all if there is loose or rucked fabric anywhere. Place your baby with their feet at the bottom of the cot. Stop using a bassinet sleeve once your baby can roll or sit unaided. A cot sleeve is a bedding product. It is not a safety device, and it makes no claim to reduce the risk of SUDI.

Questions parents actually ask

Is a bald spot on the back of my baby's head normal?
Yes. In the one study that measured it, around one in five babies had it. It is a stage rather than a problem.

When does the baby bald spot go away?
Most babies show clear regrowth somewhere in the second half of the first year, once they are spending less time lying flat. Some fill in sooner.

Can I prevent a baby bald patch?
Not really, and this is the part most articles get wrong. The shed runs on a timetable set before birth. Supervised tummy time and alternating which way your baby's head faces are both worth doing, but their real benefit is for head shape, not hair.

Is my baby losing hair because of the cot sheet?
Not the shed itself. A rougher surface can work on the hair that is there, which is a different and much smaller effect.

My baby started losing hair at six months, not two. Is that different?
It can be, simply because it falls outside the usual window. Worth mentioning to your Plunket nurse or GP.

Does a bald patch mean my baby has a flat head?
They are not the same thing, though they can appear together. Flat head, or positional plagiocephaly, comes from sustained pressure on one part of a soft skull. The bald patch does not. If the shape of the head itself looks uneven, raise it early, since it responds best to early attention.

Will a hat or bonnet help?
Not with the shed. A soft silk bonnet can be useful for tangles in longer or curlier hair further down the track, but it is not a treatment for anything.

Does the new hair grow back the same?
Often not. Colour and texture frequently change between the hair a baby is born with and the hair that replaces it.

If you would like a gentler surface for the months of regrowth, our silk cot sleeves and cot sheets are 100% mulberry silk, made to slip snugly over the head end of a cot or bassinet mattress and to survive being washed as often as real life requires.

The patch will go. In a year you will be looking at photographs of it, trying to remember which side it was on, faintly embarrassed by how many nights you spent reading about it. That worry is not wasted, though. It is just what it looks like when someone is paying very close attention to a very small person.