There is no safe way to use a loose blanket in a crib for a baby under 12 months old. The American Academy of Pediatrics is clear on this: an infant’s sleep space should contain nothing but a firm mattress and a fitted sheet. Loose blankets are the most common cause of accidental infant suffocation during sleep. For babies under one year, wearable blankets (sleep sacks) are the recommended way to keep your child warm at night.
If your child is older than 12 months, the risks drop significantly, and a lightweight blanket can be introduced with some precautions. Here’s what you need to know at every stage.
Why Loose Blankets Are Dangerous for Infants
A baby who gets a blanket over their nose and mouth may not have the strength or coordination to push it away. Airway obstruction from soft objects or loose bedding is the single most common mechanism behind accidental infant suffocation. Blankets also create risks of entrapment (getting wedged between the blanket and crib slats) and strangulation.
The risk isn’t just theoretical. Soft bedding in a shared sleep surface increases the chance of death by two to five times compared to a bare surface. A large percentage of infants who die during sleep are found with bedding covering their face or head. Even a thin muslin blanket can conform to a baby’s face and block airflow.
What to Use Instead: Birth to 12 Months
Sleep sacks, also called wearable blankets, give your baby the warmth of a blanket without any suffocation risk. A 2019 analysis found that sleep sacks are “as safe, if not safer, than other bedding” for preventing SIDS. They work from the newborn stage through about age two.
When choosing a sleep sack, look for one that is sleeveless so your baby’s arms stay free. If your baby rolls onto their stomach, free arms allow them to push up and reposition. The sack should fit snugly around the chest and neck so it can’t ride up over the face, but be roomy enough around the hips and legs for kicking. Sizing matters: a sack that’s too large can bunch up near the face, creating the same hazard you’re trying to avoid.
For newborns who are still being swaddled, the transition to a sleep sack typically happens around two months or whenever your baby starts showing signs of rolling over. Once a baby can roll, swaddling becomes dangerous because they need their arms to reposition themselves. A sleeveless sleep sack is the natural next step.
Choosing the Right Warmth
Sleep sacks come in different thicknesses measured in TOG ratings. A lower TOG (around 0.5 to 1.0) works for warmer rooms, while a higher TOG (1.5 to 2.5) suits cooler environments. The recommended nursery temperature is 68 to 72°F (20 to 22°C). At that range, a medium-weight sleep sack over a cotton onesie is usually enough.
If your baby feels hot to the touch, looks flushed, has damp hair, or seems unusually fussy or sluggish, they may be overheating. Tiny red bumps in skin folds, around the neck, or on the bottom (heat rash) are another sign you’ve overdressed them. A normal baby temperature is around 97.5°F (36.4°C), and anything at or above 100.4°F (38°C) is a fever.
After 12 Months: Introducing a Blanket
Once your child passes their first birthday, the risk of SIDS drops sharply and most toddlers have the motor skills to move a blanket away from their face. This is when you can begin introducing a light blanket if you choose to. Many parents continue using sleep sacks well past this point, which is perfectly fine.
If you do introduce a blanket, keep it lightweight and small. A thin, breathable blanket, no larger than a standard receiving blanket, is ideal. Heavy quilts, comforters, and adult-sized blankets don’t belong in a crib or toddler bed. The blanket should be small enough that it can’t get wrapped around your child’s neck or tangled around the crib hardware.
Some safety guidelines outside the U.S., particularly from the UK’s Lullaby Trust, describe a “feet to foot” method: place your baby with their feet touching the bottom end of the crib, then tuck a thin blanket firmly under the mattress at the sides and foot, no higher than chest level. This reduces the chance of the blanket sliding up over the face. While this approach is used in some countries for older babies, the AAP does not endorse it for infants under 12 months and still recommends a bare crib with a wearable blanket instead.
Weighted Blankets Are a Separate Risk
Weighted blankets should never be used for children under two years old. Even for older toddlers, a weighted blanket should not be used overnight. The blanket should be removed once the child falls asleep. The general rule is that a weighted blanket should weigh no more than 10% of the child’s body weight, and the child should be able to push it off independently. It should never cover the head or neck, and it shouldn’t hang over the sides of the bed where it could pull a child down or create entanglement.
Keeping the Crib Bare but Comfortable
Parents often worry their baby is cold at night, which is what drives the urge to add blankets in the first place. In practice, babies regulate temperature well when the room is in the 68 to 72°F range and they’re dressed in a sleep sack over a single layer of clothing. You can check by touching the back of your baby’s neck or their chest. Cool hands and feet are normal and don’t mean your baby is cold.
Beyond blankets, the same rules apply to every other soft item. Pillows, stuffed animals, bumper pads, and nonfitted sheets all increase risk and should stay out of the crib for the entire first year. The safest crib looks bare, and that’s exactly the point.