Safe Sleep for Newborns: The ABCs, What Belongs in the Crib, and What Doesn't

The instinct is to want more in the crib, not less. A soft blanket for the cold nights. A little stuffed animal. A wedge to keep the baby from rolling. It feels like care.

The safest crib is the emptiest one — and that is the hardest thing about safe sleep. Almost every recommendation on this page is a small, boring, counter-intuitive habit that will not feel like it is doing much. But taken together, those habits are the reason U.S. infant sleep-death rates fell sharply after the Back to Sleep campaign started in 1994, and they are what the American Academy of Pediatrics, the NIH's Safe to Sleep campaign, and every major pediatric group now recommend in almost identical words. This page walks through what those habits actually are, sourced back to those groups, so you can set the crib up once and stop second-guessing yourself at 3 a.m.

01The ABCs of safe sleep

You will hear pediatricians shorthand it as the ABCs: Alone, on the Back, in a Crib. That is the whole method in five words. Everything else on this page is what those five words actually mean when you are standing over the bassinet at midnight.

The recommendations below all come from the AAP's 2022 sleep-related infant death guidance, which is what the NIH's Safe to Sleep campaign and the CDC also follow. When those three agree — and on safe sleep they do — that is as close to settled as pediatric guidance gets.

02On the back — every nap, every time

For every sleep, day or night, put your baby down on their back. The AAP is direct: "Babies who sleep on their backs are much less likely to die suddenly" than babies on their stomachs or sides. NIH's Safe to Sleep says the same thing more plainly: "Research shows that the back sleep position carries the lowest risk of SIDS."

The most common worry is choking — that a baby on their back will spit up and inhale it. It is the wrong worry. As the AAP puts it, "The gag reflex prevents choking, even for babies with reflux." A baby lying flat on their back and turning their head to spit up is doing exactly what their body is built to do.

Side sleeping does not count as an alternative — a baby propped on their side can easily roll onto their tummy. Back means back. And it means for every nap, not just overnight. Most sleep-related infant deaths that happen in daytime naps happen precisely because a caregiver made an exception for a "quick" sleep.

03On a firm, flat surface — and what "firm" actually means

The sleep surface should be firm, flat, and level. Safe to Sleep spells out what those words mean: "firm" (springs back when pressed), "flat" (like a table, not a hammock), "level" (not angled), and "covered with only a fitted sheet."

The AAP's test for firm is the one to remember: "A firm surface means that it shouldn't indent when your baby is lying on it." A mattress that dips under the baby's face is a suffocation risk, even if it feels cozy to you. If you press it and your hand leaves an impression, it is too soft.

Any surface tilted more than about 10 degrees is unsafe for sleep, which is why the AAP is blunt: "Inclined surfaces exceeding 10 degrees are unsafe." That rules out the inclined "sleepers" that were recalled a few years ago, and it rules out propping the head of the mattress up on books to "help with reflux." Do not do it.

The mattress itself should be the one that came with the crib or bassinet, meeting the CPSC (federal safety) standards. Cover it with a tight fitted sheet — no extra pad, quilted topper, sheepskin, or lambskin between the sheet and the mattress.

04In their own space, in your room

Room-share, but do not bed-share. The AAP recommends keeping your baby's sleep area — a crib, bassinet, or portable play yard — in the room where you sleep for at least the first six months. The reason: "The AAP recommends room sharing because it can decrease the risk of SIDS by as much as 50%." Cleveland Clinic cites the same 50% figure and the same six-month floor.

Room-sharing is not the same as bed-sharing. Safe to Sleep draws the line clearly: "Room sharing means baby has their own sleep space (crib, bassinet, or portable play yard) in your room, separate from your bed." The AAP is more direct about the other option: "Never sleep with your baby under any circumstances." That includes sofas, recliners, and armchairs — which are actually more dangerous than beds, because a baby can get wedged between a cushion and the frame.

The safest setup is boring: your bed against one wall, the bassinet or crib next to your side of it, close enough that you can reach over and put a hand on the baby without getting up. Same room, different surfaces.

05What comes out of the crib

Everything that is not the baby or the fitted sheet comes out. Safe to Sleep puts it as one line: place the baby "in a separate sleep area designed for a baby that is firm, flat, and level, with no toys, soft objects, comforters, quilts, pillows, or blankets." That includes the little stuffed animal from the shower, the swaddle blanket you're not actively using, and the tiny pillow that came in the bassinet.

The reason to be strict about this is not fussiness. It is that a newborn cannot reliably move something soft off their face. What looks like a cozy corner to us is, to a five-week-old, an object they cannot move.

06The other things that quietly help

Four small habits show up in every major safe-sleep recommendation because the evidence is consistent. None of them replace the ABCs, but they add up.

• Breastfeed if you can. The AAP notes that "evidence shows human milk reduces SIDS risk," and MedlinePlus lists breastfeeding as a specific SIDS risk-reduction step. Any breastmilk helps; you do not have to be exclusive.
• Offer a pacifier at nap and bedtime. The AAP recommends offering pacifiers at nap and bedtime to reduce SIDS risk. If your baby is nursing, wait until breastfeeding is well established — around 3 to 4 weeks — before introducing one, and do not attach the pacifier to a clip, cord, or clothing during sleep. If it falls out mid-sleep, you do not need to put it back.
• Keep the room cool. Overheating is a known risk factor. MedlinePlus recommends keeping "the room at a comfortable temperature for an adult" — usually somewhere around 68-72°F. If you would sleep comfortably in what the baby is wearing, they are probably fine.
• No smoke or vape near the baby, ever. MedlinePlus and Cleveland Clinic both flag smoking during pregnancy and secondhand smoke around the baby as significant SIDS risk factors. That includes vaping and e-cigarettes.

One more thing that is not about the crib but is part of the AAP's guidance: supervised awake tummy time, every day. The AAP recommends gradually building up to "15-30 minutes daily by seven weeks old." It helps neck and shoulder strength, which is what eventually lets your baby roll safely — and it counteracts the flat spot that back-sleeping can cause on the head. Our guide to tummy time for newborns walks through how to start.

07Swaddling — how to do it safely, and when to stop

Swaddling is allowed, but the AAP is careful to note that "swaddling is permissible but doesn't reduce SIDS risk." It can help with the newborn startle reflex; that is a soothing benefit, not a safety benefit.

Three rules make it safe:

• Always on the back. A swaddled baby who rolls onto their stomach cannot lift their head or push up with their arms. That is the risk you are avoiding.
• Stop as soon as your baby shows any sign of trying to roll. The AAP puts it plainly: "Stop swaddling as soon as your baby shows any signs of trying to roll over." That is usually around 2 to 4 months, sometimes earlier. When in doubt, move to a wearable sleep sack.
• Room to breathe, and room for the hips. The AAP says you should be able to fit "two or three fingers between the baby's chest and the swaddle," and the hips should be able to bend up and out. Nothing weighted, ever.

For the actual technique, our step-by-step swaddling guide walks through the fold. And on whether the arms go in or out, the AAP says the honest answer: "There is no evidence with regard to SIDS risk related to the arms swaddled in or out." Do what settles your baby.

08Car seats, swings, and "just for a minute"

A car seat is a car seat. A swing is a swing. Neither is a sleep surface. If your baby falls asleep in one on the way home from an errand, move them to the crib or bassinet as soon as you can safely do it — do not leave them buckled in an inclined seat for a two-hour nap on the living-room floor.

The same goes for baby loungers and "nap nests" with names that sound like sleep products. If it's soft, if it's angled, or if it's not a CPSC-compliant crib, bassinet, or play yard, it is not for sleep. This is one of the places where the marketing and the medicine disagree — and the medicine is right.

09The point of all this

Safe sleep is genuinely boring. There is no clever product to buy, no trick to learn, no premium bassinet that unlocks a safer night. There is a fitted sheet, a firm flat surface, a baby on their back in your room, and nothing else in the crib. That is it. And it is the single most protective set of habits you can put in place for a newborn.

The rest of the newborn learning curve — feeding, burping, when to call the pediatrician, and how the first few weeks actually feel — is on our newborn basics guide, each piece sourced the same way this one is. If you are still pregnant, our week-by-week planner puts the crib setup on the right week so it is done before you're the one running on two hours of sleep.

Questions parents actually ask

Newborn Weeks is planning help, not medical advice — always follow your own doctor, midwife, or pediatrician.