Incubators and Keeping a Preterm Baby Warm

What an incubator is for

Bliss describes incubators as clear boxes that help keep a baby warm, because premature or sick babies struggle to stay warm on their own. That single sentence covers most of it, but the reason it matters is worth spelling out. A baby who is losing heat burns calories to make more, and calories spent on warmth are calories not spent on growing. Warmth is therefore a feeding intervention as much as a comfort one.

There is a second job, less obvious. Bliss explains that closed incubators hold heat and humidity in, which stops too much moisture evaporating from a baby's fine skin. Very preterm skin is not yet a waterproof barrier. Humidity in the first days protects fluid balance and the skin itself, and it is dialled down over the following weeks as the skin matures.

The two kinds you will see

Bliss describes closed boxes with hand holes in the sides, and open-topped versions with an overhead heater or a heated mattress. Which one your baby is in is about how much support they need, not how ill they are in some absolute sense — an open-topped heated cot makes handling easier and is often a step towards an open cot.

The probe, and why the alarm goes off

Bliss explains that incubator temperature is controlled in two ways: with manual controls, or automatically using a sensor taped to the baby's skin. If the sensor falls off or misreads, an alarm sounds and a nurse checks. This is one of the commonest false alarms on a unit, and knowing that removes a great deal of unnecessary fear at the cot side.

Why there is a cover over the top

Many units drape a quilted cover over the incubator. Bliss lists reducing light and noise as part of developmental care, alongside making a nest to help a baby feel secure and changing how a baby is disturbed. The cover is not hiding anything from you. Lift the corner, or ask for it to be lifted, whenever you want to look at your baby.

When the door opens

The hand holes are for you as much as for staff. Comfort holding — one still, cupped hand over your baby's head and another over their feet, rather than stroking — is what most units teach first, because random touch can be overstimulating for a very preterm baby while steady containment is calming.

Kangaroo care usually starts earlier than parents expect. Ventilated babies are routinely moved for skin-to-skin with two staff present. NICE guideline NG124 tells teams to tell parents about the benefits of touch, including skin-to-skin, and to recognise parents as partners in their baby's care. Long cuddles are better than frequent short ones, because the moves in and out cost your baby energy.

The move to an open cot

This is one of the clearest signposts on the whole admission and there is no fixed weight for it. It happens when your baby can hold a normal temperature dressed and wrapped in an open cot, which usually arrives alongside steady weight gain and often somewhere in the mid-30s of postmenstrual weeks. Units generally do a trial: out of the incubator, temperature checked frequently, and back in if it drops. A failed first attempt is genuinely routine.

It is worth asking, at ward rounds, what your baby's current incubator temperature setting is doing. A setting that has been coming down for a week is the move approaching.

Home is deliberately cooler

Parents leave a warm unit and assume the house should match it. It should not. The Lullaby Trust advises keeping every room where a baby sleeps between 16 and 20°C, and notes explicitly that this will be cooler than the neonatal unit, because babies on a unit often find it harder to keep warm — and that a baby is kept in hospital until they can maintain their own temperature.

The Lullaby Trust also says to check a baby's temperature by feeling the back of the neck or chest rather than hands or feet, which usually feel colder than the rest of the body.

Hats come off at home

This surprises almost every neonatal parent. The Lullaby Trust states that premature babies often wear hats on the unit, but that once home you should stop using hats indoors, because babies lose heat through their heads and a hat indoors can make them too hot — and overheating raises the risk of sudden infant death. The same applies to the rolled-up towels and nests used in an incubator: they belong to a monitored environment, not a cot at home.

What to ask

Ask whether your baby is in humidity and when it is due to come down. Ask what the incubator is set to and whether that setting is falling. And ask when a trial in an open cot is planned. Those three answers together tell you more about where you are in the admission than the weight does.

Clothes, and when your baby can wear them

Very preterm babies are nursed naked in humidity so that skin, lines and colour can be seen, which is one of the harder things to look at early on. As humidity comes down and temperature control improves, a vest and a hat arrive, then a full outfit. Parents often mark that day as the moment their baby stopped looking like a patient. Tiny clothes designed to open flat or fasten at the shoulders are easier around lines, and units will tell you what fits around the equipment your baby has.

Twins and multiples

Twins are frequently nursed side by side or in the same incubator on a neonatal unit. The Lullaby Trust notes that premature or low birth weight multiples are often slept close together on the unit, to mimic the womb and to support heart rate and breathing, and that co-bedding in one cot can be continued at home following safer sleep advice. Ask your unit what they do and why, because practice varies.