This is the one topic on this site where we would rather over-state the caution than under-state it.
The guidance is unambiguous: place your baby on their back for every sleep, day and night, until their first birthday. Public health campaigns promoting back sleeping are associated with substantial reductions in sudden infant death across many countries. It is the most effective single action available to parents.
Side sleeping is not a safe alternative. A baby placed on their side can roll onto their front. If someone advises side positioning for reflux or any other reason, ask your pediatrician directly before changing anything.
The rest of the safe sleep picture:
- Firm, flat surface. A cot, crib or moses basket mattress. Not a sofa, armchair, car seat, bouncer or pillow. Sleeping on a sofa with a baby carries particularly high risk.
- Clear space. No pillows, loose blankets, cot bumpers, positioners, wedges or soft toys. A sleep sack replaces blankets because it cannot ride up over the face.
- Room sharing, not bed sharing. Sleeping in the same room as your baby, on a separate surface, for at least the first six months is protective.
- Avoid overheating. Room around 16 to 20°C, no hats indoors, and check the back of the neck rather than hands or feet.
- Smoke-free environment, both during pregnancy and after.
- Breastfeeding and offering a dummy at sleep time are both associated with reduced risk.
Common questions:
"My baby sleeps better on their front." Many do — and that is precisely why the risk exists, because deeper sleep on the front is associated with reduced arousal. Sleeping more soundly is not the same as sleeping more safely. Back is still the answer.
"What if they roll over on their own?" Once a baby can roll both ways independently, usually somewhere around four to six months, you do not need to keep returning them to their back all night. Still always *place* them on their back to start. Stop swaddling at the very first sign of rolling.
"What about flat head?" Positional flattening is a real but largely cosmetic and manageable issue, and it is not a reason to front-sleep. Counter it with plenty of supervised awake tummy time, alternating which end of the cot you lay them down at, and limiting time in car seats and bouncers. Raise persistent flattening with your pediatrician.
"They have reflux." Back sleeping remains recommended for almost all babies with reflux. Do not tilt the mattress or use a positioner without explicit medical direction.
This article is general information, not medical advice. Safe sleep guidance is updated periodically and can vary by country. Follow the advice of your own pediatrician or health service, and ask them about anything specific to your baby — particularly if your baby was premature, has low birth weight, or has any medical condition affecting breathing or feeding.