The safest way to lay your baby in a bassinet is on their back, on a firm and flat surface, with nothing else in the sleep space. That’s the short answer. But the physical act of getting a sleeping baby from your arms into the bassinet without waking them, keeping them comfortable, and making sure everything around them is safe involves more detail than most parents expect.
Always Place Your Baby on Their Back
Every time your baby sleeps, whether it’s nighttime or a nap, they should be placed flat on their back. This applies to every caregiver, every sleep, until your baby turns one. Side sleeping is not considered safe. The American Academy of Pediatrics links back sleeping with a significant reduction in sleep-related infant deaths, and room sharing (sleeping in the same room on a separate surface like a bassinet) can reduce the risk of SIDS by as much as 50%.
Some parents worry that a baby sleeping on their back might choke if they spit up. Healthy infants have reflexes that clear their airway automatically. Back sleeping remains the recommendation even for babies with reflux.
How to Lower Your Baby Without Waking Them
The biggest challenge most parents face isn’t the position itself. It’s the transfer. You’ve spent 20 minutes rocking your baby to sleep, and the moment you lean over the bassinet, their arms fly out and they’re wide awake. That sudden startle is the Moro reflex, an involuntary response triggered when your baby senses a falling sensation.
To minimize this, lower your baby horizontally rather than head-first or feet-first. Keep their body pressed against your chest as long as possible during the descent, so they continue to feel supported. When you reach the mattress, let their bottom and back make contact first, then slowly slide your hands out from underneath. Pause between each micro-movement. If you feel your baby tense, hold still for a few seconds before continuing.
Some parents find that placing one hand on their baby’s chest for 30 to 60 seconds after laying them down helps them settle. The gentle pressure mimics the feeling of being held and can prevent the startle reflex from firing during those first moments on the mattress. If your baby is swaddled, the transfer tends to be easier because their arms are contained and less likely to flail.
Swaddling Safely in a Bassinet
Swaddling can help newborns feel secure and sleep more soundly, but it needs to be done correctly to protect your baby’s hips. A safe swaddle keeps the legs in a natural “frog leg” position, with hips slightly bent and knees apart. The lower half of the swaddle should be loose enough that your baby can move their hips and knees freely. Wrapping the legs straight and tight can contribute to hip dysplasia, and improper swaddling is actually flagged by the AAP as a reason to screen a baby’s hips with ultrasound before 6 months.
Sleep sack swaddles with Velcro wraps around the chest and a roomy pouch at the bottom are designed with this in mind. They keep the arms snug while leaving plenty of space for the legs.
The important cutoff: once your baby shows any signs of rolling over, stop swaddling immediately. A swaddled baby who rolls onto their stomach cannot push themselves back over. This milestone and the transition out of the swaddle often happen around the same time your baby is ready to move from a bassinet to a crib.
What Should (and Shouldn’t) Be in the Bassinet
The bassinet should contain a firm, flat mattress with a fitted sheet and nothing else. No pillows, no blankets, no stuffed animals, no bumpers, no sleep positioners. The U.S. Consumer Product Safety Commission specifically warns against weighted blankets and weighted swaddles as well. Many young babies cannot lift their heads to pull away from soft objects near their face, so even items that seem harmless can become suffocation hazards.
Use only the mattress that came with your bassinet. Aftermarket mattresses must be at least the same size as the original and must lay flat against the floor of the product with no gaps. A mattress that’s too small, too soft, or doesn’t fit snugly creates pockets where a baby’s face can become trapped. If you’re unsure whether a replacement mattress is compatible, stick with the manufacturer’s original.
Keep the Surface Flat, Even for Reflux
Parents of babies with reflux are sometimes tempted to prop up one end of the bassinet or use a wedge to keep their baby at an incline. The AAP specifically recommends against this. The sleep surface should be firm and noninclined. Inclined surfaces can cause a baby to slide into a position that compresses their airway. If your baby has significant reflux, talk to your pediatrician about management strategies, but elevating the bassinet is not one of them.
Preventing a Flat Spot on Your Baby’s Head
Because your baby spends so much time on their back, one side of their head can start to flatten. You can reduce this risk by alternating which direction your baby faces each time you lay them down. One night, place them with their head at the top of the bassinet. The next night, orient them so their head is at the opposite end. Babies naturally turn to look toward the room or toward you, so switching their orientation changes which side of the head bears the pressure.
Supervised tummy time while your baby is awake also helps by taking pressure off the back of the skull and building the neck and shoulder strength your baby will need for rolling and sitting.
Room Temperature and Clothing
Overheating is a risk factor for sleep-related infant deaths. Dress your baby lightly for sleep and keep the room at a temperature that feels comfortable for you. A good rule of thumb: if you’d be comfortable in a single layer, your baby needs one layer more than that. Signs your baby may be too warm include sweating, flushed cheeks, damp hair, or a chest that feels hot to the touch. Since blankets don’t belong in the bassinet, a sleep sack is the safest way to add warmth without loose fabric.
When to Transition Out of the Bassinet
Most babies use a bassinet from birth until around 4 to 6 months. The exact timing depends on your baby’s development and the specific product’s limits. You should move your baby to a full-size crib if any of the following happen first: your baby can roll over, push up on their hands and knees, sit independently, or reach the height or weight maximum listed by the bassinet manufacturer.
Rolling is the most urgent trigger. Once your baby shows signs of rolling, they need the larger, deeper sleep space of a crib or portable crib. A bassinet’s shallow sides are not designed to safely contain a mobile baby. Check your bassinet’s manual for the specific weight limit, as these vary by brand and typically range from 15 to 20 pounds.
The CDC recommends keeping your baby’s sleep area in your room for at least the first 6 months. If your baby outgrows the bassinet before then, a crib or portable crib in your bedroom serves the same purpose.