The NHS recommends against bed-sharing — and that guidance exists for good reason. But around 65–75% of UK parents co-sleep at some point. This guide is for them: five evidence-based steps to reduce risk as much as possible.
The NHS, NICE, and the Lullaby Trust all recommend that babies sleep in their own clear, flat sleep space — a cot or Moses basket — in the same room as you for at least the first six months. This is the guidance with the strongest evidence base and the lowest risk. This guide is not an alternative to that recommendation. It exists because the majority of parents will co-sleep at some point — often accidentally, often at 3am when the baby will not settle any other way — and having accurate risk-reduction information in those moments is safer than having none.
Research consistently shows that around 65–75% of UK parents share a sleep surface with their baby at some point in the first year. The gap between official guidance and actual parental behaviour is one of the most significant in infant health — and pretending it doesn't exist doesn't close it. This guide covers what the research says about risk reduction for parents who are co-sleeping, so they can do it as safely as possible.
If any of the following apply, bed-sharing is not safe and this guide cannot reduce that risk: either parent smokes (including smoking during pregnancy), either parent has consumed any alcohol, either parent has taken medication that causes drowsiness, the baby was premature (before 37 weeks), or the baby was low birth weight (under 2.5kg / 5.5lbs). In these circumstances the safest option is a bedside crib or co-sleeper cot.
The single most important step when co-sleeping: your duvet, pillows, and soft bedding must not be near the baby. Babies can become trapped against soft surfaces or have their face covered without being able to move away — this is the most common mechanism of harm in bed-sharing deaths.
In practice: push your pillow to the far edge of your side of the bed. Fold the duvet down below the baby's feet level. The baby should be on a firm part of the mattress, not on a pillow or soft topper. A cellular blanket for the baby separately — tucked in, not loose — is preferable to sharing the main bedding.
Babies who can roll (from around 4 months) can roll off a bed. Even before that, a gap between the mattress and the headboard, wall, or bed frame can trap a small baby in a position they can't get out of.
Check: is there a gap between the mattress and the headboard? Push the mattress right up against it or use a bed rail. Is the baby on the side closest to a wall or bed rail? If so, ensure the gap between the mattress and wall is not large enough to trap them. A parent should be between the baby and the edge of the bed — the baby should be on the inside.
Never place the baby between two adults — the risk of either adult rolling onto the baby is significantly higher in this position.
Even in a shared sleep surface, the basics of safe sleep still apply: baby on their back, face uncovered, not too hot.
The recommended position for a breastfeeding mother who co-sleeps is known as the cuddle curl: lying on your side facing the baby, your lower arm extended above the baby's head (preventing you from rolling forward), your knees drawn up slightly below the baby's feet (preventing you from sliding down towards them). This position creates a natural protected space and is associated with lower risk than other co-sleeping positions.
Check the baby's temperature periodically — shared body heat means they can overheat more easily than in a cot. Feel the back of the neck: warm but not sweaty is right.
The most important thing in this guide: if you are at risk of falling asleep while feeding, move to the bed rather than the sofa.
The research on this is unambiguous. Sleeping with a baby on a sofa or armchair is 50–67 times more dangerous than bed-sharing. The risk of a baby becoming trapped in the gap between the parent and the furniture, or having their face pressed against a soft cushion, is dramatically higher. There is no safe way to co-sleep on a sofa.
Many parents who end up on the sofa do so because they felt falling asleep there was less risky than 'deliberately' bed-sharing. It is the opposite. If you're going to fall asleep with your baby, do it in a bed where you can implement the risk-reduction steps above. Have the bed prepared in advance — pillow pushed away, duvet folded down — so that you can move there quickly at 3am rather than making decisions when exhausted.
The evidence is consistent on which factors most significantly increase risk during bed-sharing:
Smoking is the highest individual risk factor — including smoking outside the home, or smoking during pregnancy even if you've stopped now. The biological mechanism is not fully understood, but the epidemiological evidence is very strong.
Alcohol: even a small amount reduces your arousal response during sleep. The threshold is lower than most people assume. If you've had anything to drink, bedside cot only.
Extreme fatigue: normal new-parent sleep deprivation is one thing; if you are beyond normally tired — after a particularly difficult stretch, or if you have a condition affecting sleep — your arousal response during sleep is reduced.
Medication: antihistamines, cold and flu remedies, some antidepressants and many other medications affect sleep depth. Check the label; if it causes drowsiness, treat it like alcohol.
None of these factors are moral judgements. They are physiological mechanisms. Knowing them clearly allows you to make an honest assessment of your situation on any given night.