The short answer
Yes for the first hours, no for almost everything after that. A hat belongs in the delivery room and outdoors in cold weather. It does not belong on a baby who is indoors, and it must never be left on a sleeping baby, because a covered head is one of the ways a baby overheats, and overheating is a modifiable risk factor in safe-sleep guidance.
| Situation | Hat? | Why |
|---|---|---|
| Delivery room, first hour or two | Usual practice, and harmless | Part of the standard warm-chain routine, though the evidence for the hat specifically is weaker than most people assume |
| Indoors, awake | No | A heated room plus a hat is how a newborn gets too warm without anyone noticing |
| Indoors, asleep | No, take it off | Explicit advice from safe-sleep bodies. A covered head cannot lose heat |
| Outdoors below about 15 °C | Yes | The head is a large share of a newborn’s surface area and it is the part you cannot layer |
| In a car seat, heated car | Take it off once the car is warm | Same overheating problem, and you cannot see a flushed baby facing backwards |
| Preterm or low birth weight | Follow your unit’s instructions | A genuinely different clinical situation, not covered by general advice |
The rule that gets people through it: a hat is outdoor clothing. It goes on with the coat and comes off with the coat.
The claim to retire first
You will read, constantly, that babies lose most of their body heat through their heads, often with a figure attached, sometimes as much as half. It is not true, and the number matters because it is the reason people leave hats on indoors.
What is true is narrower and still worth knowing. A newborn’s head is roughly 19 per cent of total body surface area, against about 7 to 9 per cent in an adult. Those proportions come from the Lund and Browder chart used in burns assessment, which exists precisely because adult proportions do not apply to infants. So the head is a disproportionately large radiator compared with an adult’s, and it is also the part of a baby you cannot easily add a layer to.
Nineteen per cent is not most. It is about a fifth, and it is the correct basis for the advice: cover the head outdoors in the cold, where a fifth of the surface area matters, and uncover it indoors, where the same fifth is how the baby sheds heat that a warm room and a sleeper are adding.
What the evidence says about hats at birth
The hat in the delivery room is part of a standard sequence: dry the baby immediately, put them skin to skin, cover both, keep the room warm. The World Health Organization’s thermal protection guidance builds that sequence around drying and skin-to-skin contact, which are the parts with the strongest evidence behind them.
The hat itself has a thinner evidence base than its ubiquity suggests. A 2023 study in the Journal of Perinatal & Neonatal Nursing looked at what happened when one hospital stopped putting hats on healthy full-term newborns at birth. Comparing 482 infants over 38 weeks’ gestation and over 2,500 g before and after the change, it found no statistically significant difference in the proportion who became hypothermic, with or without a hat.
That is one study at one institution, and it says nothing about preterm or small babies, who are a different clinical problem entirely. But it is a useful corrective to the idea that the hat is doing the work. For a healthy full-term newborn, the drying and the skin-to-skin contact are doing the work.
None of which is a reason to refuse a hat in a delivery room. It is a reason not to treat it as essential equipment for the following six weeks.
Why the hat comes off indoors
This is the part with clear, consistent guidance behind it from more than one national body, and it is the part most often got wrong.
Safe-sleep guidance advises removing hats and head coverings once a baby is indoors, and never leaving a hat on a sleeping baby. The Lullaby Trust puts it directly: take hats off indoors, because babies lose heat through their heads and a covered head can make a baby overheat. The American Academy of Pediatrics reached the same position in its safe-sleep guidance, recommending against hats indoors outside the first hours of life.
The mechanism is simple and slightly uncomfortable to think about. A newborn cannot remove a layer, cannot move away from a heat source, cannot shiver to warm up or say that they are too hot. The head is the one uncovered surface left doing the regulating. Cover it in a heated room and you have removed the only adjustment the baby had.
The check that works: feel the back of the neck or the chest, not the hands or feet. Newborn hands and feet run cool and mislead almost everyone. Warm and dry at the chest is right. Damp, sweaty or hot means a layer too many, and the hat is the first layer to remove.
Room temperature guidance differs slightly by country but sits in a narrow band, commonly cited as 16 to 20 °C for a baby’s room. Set the room, dress for the room, and skip the hat.
When a hat is genuinely the right call
Outdoors, in the cold, without much argument. The head is a fifth of the surface area and the one part a pramsuit does not cover.
| Outside temperature | Head | Note |
|---|---|---|
| Below 10 °C | A close-fitting hat that covers the ears | Ears are the part that actually hurts, and the part hats most often miss |
| 10 to 15 °C | A thin cotton or knit hat | Comes off as soon as you go inside or into a warm car |
| Above 15 °C | Usually nothing | Unless it is windy, which changes it more than the temperature does |
| Strong sun, any temperature | A wide-brimmed sun hat | A completely different garment doing a completely different job |
The wind point is worth its own line. A still 12 °C and a windy 12 °C are not the same for a baby in a pram at knee height, and the head and ears feel it first.
Preterm and small babies are a different case
Everything above is about healthy full-term newborns. Babies born early or small have a larger surface area relative to mass, less insulating fat, and less developed thermoregulation, and they are managed under clinical protocols rather than general advice.
If your baby was preterm, low birth weight, or spent time in a neonatal unit, the instructions from that unit override anything in this article. That is not a formality; the thresholds are genuinely different.
What makes a newborn hat worth keeping
Most newborn hats are gifts and most of them are wrong, in ways that are easy to see once named.
- It has to stay on. A hat that rides up over the eyes every two minutes is worse than no hat, and a newborn cannot push it back. Soft rib or a shaped crown stays put; a straight tube does not.
- No ties, no cords, no ribbon under the chin. Cords at the neck are a strangulation hazard and are restricted on children’s clothing in both the US and the EU for that reason.
- No pom-poms, bows or appliqués that can detach. Anything small enough to come off is small enough to be a choking hazard. Pull firmly on everything before first wear.
- Flat seams, ideally a rolled or bound edge. A ridged seam sits across the forehead of a baby who will be lying down for most of the day.
- The right size, which is smaller than you think. Newborn hats sized 0–3 months usually swamp a small newborn, and a hat that slides is a hat over the face.
- Breathable fabric. Cotton or a cotton knit for most weather; wool or a lined knit only for genuine cold, and only outdoors.
Two you can skip: the hospital-issue hat, which does its job for a day and is rarely a good fit afterwards, and anything decorative bought in more than one size. You need two, and they will be outgrown quickly.
The going-home outfit and the car seat
The first journey is where the hat question gets confused with the car seat question, and they have different answers.
A hat is fine in a car seat, because it sits outside the harness and does not affect how the straps fit. What is not fine is bulky clothing underneath the harness, which compresses in a crash and leaves slack in straps that felt tight. That is the rule that decides the whole outfit, and it is set out along with the fabric and construction choices in the coming home outfit.
What to watch instead is the temperature swing. A car goes from outside temperature to warm in ten minutes, and a rear-facing baby is the person in the car you can see least. Take the hat off once the heating is running, and check the chest rather than assuming.
Sun hats are a separate question
A sun hat is not a warm hat with a brim. It is a different garment solving a different problem, and the guidance runs the other way: for a baby under six months the priority is shade and covering rather than exposure, because infant skin is thinner and sunscreen use is restricted at that age.
What matters on a sun hat is brim width, back-of-neck coverage and a weave you cannot see light through. Fabric sun protection, including what a UPF rating actually means and where it is and is not tested, is covered in UPF 50 swimwear for kids.
What this guide does not claim
This is not medical advice and it is not safe-sleep advice. The sources below are the national bodies whose guidance we are describing, and their wording is what should be followed. Questions about your baby’s temperature, sleep environment or feeding belong with your midwife, health visitor or pediatrician.
The 2023 study cited is a single-institution before-and-after comparison in healthy full-term newborns. It is not a randomised trial, it does not apply to preterm or low birth weight babies, and it is quoted here to qualify a common assumption rather than to settle a clinical question.
Surface area proportions are from a clinical assessment chart and are approximations that shift with age. They are given to replace a wrong number with a roughly right one, not to support a calculation.
We sell baby clothing, including hats. The argument here is that you need fewer of them than you will be given, which is not a sales pitch, and the construction checklist is the part we would stand behind applied to anyone’s hats.
Frequently asked questions
Do newborns have to wear hats? Only in the delivery room and outdoors in cold weather. Indoors a hat should come off, and it should never be left on a sleeping baby.
Do babies lose most of their heat through their heads? No, that is a myth. A newborn’s head is roughly 19 per cent of body surface area against about 7 to 9 per cent in an adult, which is disproportionate but nowhere near most.
Why should a hat come off indoors? Because a covered head is how a newborn overheats in a warm room, and overheating is a modifiable risk factor in safe-sleep guidance.
Can my baby sleep in a hat? No. Safe-sleep guidance from both UK and US bodies advises against hats for sleep, indoors or in a pram once inside.
Does the hat at birth actually help? Less than most people assume for a healthy full-term baby. A 2023 study of 482 newborns found no significant difference in hypothermia with or without one; drying and skin-to-skin contact are what matter.
At what temperature does my baby need a hat outside? As a rough guide, below about 15 °C, and definitely below 10 °C with the ears covered. Wind matters more than the number suggests.
How do I tell if my baby is too warm? Feel the back of the neck or the chest, not the hands and feet, which run cool in newborns. Damp or hot means a layer too many, and the hat comes off first.
What room temperature should a baby sleep in? Guidance commonly cites 16 to 20 °C. Set the room first, then dress for it, rather than adding layers to a room that is too cold.
Can my baby wear a hat in the car seat? Yes, because it sits outside the harness. Take it off once the car has warmed up, since a rear-facing baby is the hardest person in the car to see.
What about preterm or small babies? Different rules. Follow the instructions from your neonatal unit, because thermoregulation thresholds for small or early babies are genuinely different.
How many newborn hats do I need? Two. They are outgrown quickly, they arrive as gifts, and a hospital-issue hat rarely fits well after the first day.
What should I avoid on a baby hat? Ties or cords at the chin, pom-poms and appliqués that can detach, ridged seams across the forehead, and anything that slides down over the eyes.
Is a sun hat the same thing? No, it is a different garment. Brim width, neck coverage and a tight weave matter there, and for a baby under six months shade matters more than any hat.
My baby’s hands are cold, does that mean they need a hat? Not on its own. Newborn hands and feet are normally cooler than the trunk, so check the chest before adding anything.
Do hats help babies sleep? No, and they add risk. What helps is the right room temperature and the right number of layers for it.
About this article
Written and fact-checked by the PatPat Editorial Team. How we research, source and review what we publish is set out on our editorial standards page.
Method. The safety guidance here is described from national safe-sleep bodies rather than summarised from parenting sites, and the evidence on hats at birth is cited with its limits stated. No clinical testing was done for this article.
Corrections. An earlier version of this article on our site repeated the claim that babies lose most of their body heat through their heads. That figure is not supported: a newborn’s head is roughly a fifth of body surface area. The advice that follows from the correct number is different in one important way, which is that a hat indoors is a risk rather than a precaution.
Sources. Removing hats indoors and dressing for sleep: The Lullaby Trust, how to dress your baby for sleep, with cold weather guidance at cold weather and temperature at room temperature. US safe-sleep guidance: NICHD Safe to Sleep and AAP, A Parent’s Guide to Safe Sleep. Thermal protection at birth: WHO, Thermal Protection of the Newborn. Evidence on hats at birth: Hats Off for Full-Term Healthy Newborns: No Benefits for Thermoregulation, Journal of Perinatal & Neonatal Nursing, 2023. Surface area proportions by age: the Lund and Browder chart.
Related. What to put a newborn in for the journey home is in the coming home outfit; which size to start in is in newborn or 0–3 months; and how the common sleepwear fabrics compare is in bamboo versus fleece.
Last updated 17 September 2026 · Next review September 2027
