Loose blankets are not safe in a crib before 12 months. Here is the age guidance, what to use for warmth instead, and how to tell whether your baby is warm enough.
The short answer: not until at least 12 months. Every major pediatric safe-sleep guideline, including the American Academy of Pediatrics recommendations, says the same thing about the first year. A baby's sleep space should hold the baby, a firm flat mattress and a tight fitted sheet. Nothing else. No loose blanket, no quilt, no pillow, no crib bumper, no stuffed animal.
That is a hard rule to sit with when the nursery is cold at 3am and every baby blanket you were gifted sits folded on a shelf. So here is the reasoning, the age guidance, what to use instead, and how to tell whether your baby is actually warm enough.
Two risks drive the guidance, and both come down to the fact that young babies cannot reliably move something off their own face.
Airway obstruction. A blanket that rides up, or that a baby wriggles under, can cover the nose and mouth. An older child pushes it away without waking. An infant under a year often cannot, particularly one who has not yet learned to roll confidently in both directions.
Overheating. Babies regulate temperature less efficiently than adults do, and overheating is an independent risk factor in safe-sleep research. A blanket plus a warm room plus heavy pajamas adds up faster than parents expect.
There is a third, more practical reason: a blanket in a crib is not a stable object. It bunches, it slides, it ends up in a corner or wrapped around a leg. You cannot supervise it while you are asleep in another room.
If you are unsure where your particular child sits on that scale, the developmental milestones matter more than the calendar. A 13-month-old who rolls, sits and stands is in a different situation from a 13-month-old who is not yet mobile. Ask your pediatrician about your child specifically.
This is the standard answer, and it is a good one. A sleep sack is a sleeveless bag the baby wears over pajamas. It cannot ride up over the face, it cannot be kicked off, and it goes into the crib as part of what the baby is wearing rather than as a loose item. Most are labeled with a TOG rating, which is simply a warmth number: lower TOG for warm rooms, higher for cold ones.
A snug swaddle helps many newborns settle. The critical part is stopping the moment your baby shows any sign of rolling, usually somewhere around two to four months. A swaddled baby who rolls onto their stomach cannot push themselves back. Most families transition from a swaddle straight into a sleep sack.
A useful rule of thumb: dress your baby in roughly one more layer than you would be comfortable in for the same room. A room in the high 60s to low 70s Fahrenheit suits most babies. In Los Angeles, the more common problem is a warm bedroom rather than a cold one, especially in an older building without central air. If the room is running hot, a lighter sleep sack and lighter pajamas beat cranking the fan straight at the crib.
Do not judge by hands and feet, which are often cool on a perfectly warm baby. Slip a finger against the back of the neck or the chest. If that skin is warm and dry, your baby is fine. Sweaty hair, a flushed face or damp skin at the neck means too warm, and too warm is the direction worth correcting quickly.
Removing the blanket is only half of a safe sleep setup. The other half is what the baby is lying on. A crib mattress should be firm enough that it does not indent under the baby's weight, flat, and sized so there is no gap larger than about two fingers between the mattress and the crib frame. The fitted sheet should be made for that exact mattress and pulled tight.
Firm feels wrong to adults, and that reaction is normal. Infant mattresses are deliberately much firmer than anything you would choose for yourself, because a surface that cradles is a surface that can obstruct. Our crib mattress buying guide covers firmness, sizing and what the various certifications actually mean.
Also skip the extras: crib bumpers, sleep positioners, wedges and pillows all fall under the same "nothing else in the crib" rule, whatever the packaging claims.
There is no rush. Many toddlers stay in a sleep sack well past their second birthday, and there is nothing wrong with that, especially while they are still in a crib. The natural moment to switch is usually the move to a toddler bed or a twin bed, when the child can get in and out on their own and pull up their own covers.
When you do make the change, start with a small, thin blanket rather than a full-size comforter, and keep pillows out until at least 18 months to two years. Our guides to the best toddler mattresses and to choosing a mattress for kids and teens walk through the next stage, including when a twin mattress starts to make more sense than a crib.
After 12 months at the earliest, and many pediatricians suggest waiting until closer to 18 months. Before the first birthday, the recommendation is a completely bare crib: firm mattress, tight fitted sheet, nothing loose. Use a wearable blanket or sleep sack for warmth instead.
Twelve months is the standard threshold, but the developmental picture matters more than the birthday. A baby who rolls easily in both directions, sits up unaided and can push an object off their face is in a much safer position than one who cannot yet do those things. Check with your pediatrician about your own child.
Muslin is breathable, which helps, but breathable is not the same as safe. A loose muslin blanket can still cover a face or bunch up, so the same under-12-months rule applies. Muslin blankets are excellent for supervised awake time, for tummy time and as a swaddle in the newborn weeks, just not as loose bedding overnight.
Supervised naps in the same room are a different situation from overnight sleep, and brief supervised use while you are awake and watching is not the concern the guidance addresses. The rule exists for unsupervised sleep. In practice, if you would not be watching continuously, treat it as unsupervised and leave the blanket out.
Most families make the switch somewhere between 18 months and three years, and very often it coincides with moving out of the crib into a toddler or twin bed. There is no benefit to hurrying it. If your toddler sleeps well in a sack, keeping it is a perfectly good choice.
A safe sleep setup is mostly about subtraction, taking things out of the crib rather than adding them. The one thing worth spending real attention on is the mattress underneath, because firmness and fit are the parts you cannot fix later with an accessory. If you are setting up a nursery or working out what comes after the crib, come talk to us at any of our five Los Angeles showrooms, or take our sleep quiz if the next bed in the house is yours. Same-day delivery is available across most of LA.
This article is general information, not medical advice. For guidance specific to your child, talk to your pediatrician.
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