A newborn should sleep on their back, on a firm and flat surface, with nothing else in the bassinet. That single rule, consistently followed, is the most effective way to reduce the risk of sleep-related infant death. The details below cover exactly how to set up the bassinet, what to keep out of it, and what to do as your baby grows.
Always on Their Back
Every sleep, whether it’s nighttime or a five-minute nap, should start with your baby placed flat on their back. This position keeps the airway open and actually makes choking less likely, not more. When a baby lies on their back, the windpipe sits above the esophagus. If your baby spits up, gravity pulls the liquid away from the airway rather than toward it. Babies also have a built-in reflex to swallow or cough up fluid when they’re on their backs.
When a baby sleeps on their stomach, the anatomy works in reverse: spit-up pools right at the opening of the windpipe, making aspiration easier. The tissue that triggers the protective cough reflex is also positioned in a way that responds better when a baby is face-up. So if you’ve heard that back sleeping causes choking, the opposite is true.
What Belongs in the Bassinet
A fitted sheet and nothing else. The Consumer Product Safety Commission puts it simply: “Bare is best.” That means no pillows, no blankets, no stuffed animals, no bumpers, and no sleep positioners. Very young babies cannot lift their heads to pull away from a soft object pressed against their face, so anything loose in the sleep space is a suffocation risk.
A few items that might seem harmless but should stay out:
- Weighted blankets or weighted swaddles. These restrict a baby’s ability to move and breathe freely.
- Extra mattress pads or toppers. Use only the mattress that came with your bassinet. Aftermarket mattresses must now meet the same safety standards as the original, but adding padding on top of the existing mattress creates a gap or soft surface.
- Loveys and small plush toys. Even a small stuffed animal can shift against a newborn’s face during sleep.
The Right Mattress and Angle
The bassinet mattress needs to be firm and flat. Current safety standards require that the sleep surface not sink more than 1.5 inches under a baby’s weight. If you press your hand into the mattress and it holds a deep impression, it’s too soft.
The surface should also be close to level. Safety standards cap the head-to-toe angle at 10 degrees and the side-to-side angle at 7 degrees. Inclined sleepers, rockers, and swings that exceed these angles are not safe for sleep. Car seats and bouncy chairs fall into the same category: fine for their intended purpose, not for sleeping.
Where to Put the Bassinet
Keep the bassinet in your bedroom, right next to your bed, for at least the first six months. Room sharing (without bed sharing) can reduce the risk of sudden infant death by as much as 50%, according to the CDC. Having your baby within arm’s reach also makes nighttime feeding easier and lets you hear changes in breathing or movement without a monitor.
The key distinction is room sharing versus bed sharing. Sleeping on a couch or armchair with your baby, or pulling them into an adult bed, dramatically increases risk. The bassinet gives your baby their own firm, clear surface while keeping them close.
Temperature and Clothing
Aim for a room temperature between 68 and 78°F. A gentle fan on low helps keep air circulating and has been associated with lower risk. Dress your baby in one layer more than you’d wear comfortably in the same room. A onesie with a sleep sack is a common combination, though it varies by season.
Since blankets aren’t safe in the bassinet, a wearable sleep sack is the best way to keep your baby warm. These zip on and stay in place, covering the body without riding up over the face. Check the TOG rating (a measure of thermal resistance) to match the sack to your room temperature: lighter weights for warmer rooms, heavier for cooler ones.
Signs your baby is too warm include flushed or red skin, sweating or damp hair, fussiness, and feeling hot to the touch on the chest or back of the neck. Some overheated babies won’t sweat at all but will seem unusually sluggish or listless. If your baby feels hot, remove a layer and check again in a few minutes.
Swaddling Safely
Swaddling can help a newborn sleep more soundly by reducing the startle reflex, and it’s fine to use in a bassinet with one firm rule: stop as soon as your baby shows any sign of trying to roll over. Some babies start working on rolling as early as 2 months, though the timing varies widely. Once rolling begins, a swaddle restricts the arm movement your baby needs to push up and clear their face.
When you swaddle, keep it snug around the chest but loose at the hips. A too-tight wrap around the legs can affect hip development. The swaddle should not come loose during sleep, since a free piece of fabric becomes the same hazard as a blanket. If your baby consistently breaks out of a traditional swaddle, a zip-up swaddle with a fitted design is a safer alternative.
Once you retire the swaddle, switch to a sleep sack that leaves the arms completely free. The transition can be rough for a few nights, but most babies adjust within a week.
When to Move to a Crib
Bassinets are designed for the smallest babies, and most have weight limits around 15 to 20 pounds, though yours may be lower. Check the manual for your specific model. But weight isn’t the only factor. You should transition to a crib when your baby hits any of these milestones, even if they’re still well under the weight limit:
- Rolling over. A baby who can roll is mobile enough to shift into a dangerous position against the bassinet’s shallow sides or even tip over the edge.
- Pushing up on hands and knees. This means your baby is close to crawling and needs more space to move without hitting the sides.
- Showing signs of sitting up. Bassinet walls are low. Once your baby can lean forward and balance, even briefly, they can topple out.
For many babies, the first roll happens between 3 and 5 months. That’s often what triggers the switch, well before the weight limit becomes an issue. When you do move to a crib, the same rules apply: back sleeping, firm flat mattress, nothing in the sleep space.
Putting It All Together
The setup is straightforward once you know the rules. Place the bassinet beside your bed. Use only the mattress it came with, covered by a single fitted sheet. Lay your baby on their back, dressed in a sleep sack or a snug swaddle (if they’re not yet rolling). Keep the room comfortably cool with air moving. And resist the urge to add anything soft or cozy to the bassinet, no matter how bare it looks. For a newborn, bare is exactly right.