Why Does My Baby Need To Be In An Isolette and When Can They Come Out?

A preterm baby is placed in an isolette because their body isn’t quite ready to keep itself warm on its own yet. The isolette acts like a little, carefully controlled environment—almost like a substitute for the warmth they would still be getting inside the womb.

Why preterm babies struggle to stay warm:

1. They lose heat very easily

• Preterm babies are very small with a large surface area compared to their body weight, so heat escapes quickly

• Their skin is thin and not fully developed, so it doesn’t hold heat well

• They have very little fat (especially brown fat, which helps generate heat)

2. They can’t make enough heat yet

• Full-term babies use brown fat to create heat without shivering

• Preterm babies have less of this fat and their systems aren’t fully mature, so they can’t generate enough heat to keep up with what they lose

3. Their brain’s “thermostat” is immature

• The part of the brain that regulates temperature (the hypothalamus) is still developing

• That means they don’t automatically adjust as well to being too cold or too warm

4. Staying warm takes a lot of energy

• If a baby has to work hard to stay warm, they burn calories and oxygen

• Those are the same resources they need for:

  • Growth

  • Breathing

  • Brain development

So keeping them warm isn’t just about comfort—it’s about saving their energy for growing and healing rather than staying warm.

What the isolette does

The isolette helps by doing the work your baby can’t do yet.

• Provides a warm, stable temperature

• Can control humidity, which helps prevent heat and fluid loss through the skin

• Protects from drafts and sudden temperature changes

• Allows us to adjust the environment very precisely based on your baby’s needs

How babies grow into regulating their own temperature

Babies slowly increase their ability to maintain their own body temperature because:

• They build up more body fat (including brown fat) - why optimizing their nutrition is so important.

• Their skin becomes thicker and better at holding in heat

• Their brain’s temperature control system matures

• They get bigger, so they lose heat less quickly

What the medical team is looking for before weaning the temperature of the isolette

Your baby is ready when they can:

• Maintain a normal body temperature in a slightly cooler environment- so the temperature of the isolette will be turned down a little bit and then your baby's temperature will be monitored to make sure that their temperature stays the same.

• Gain weight consistently. Sometimes when the isolette temperature is turned down, your baby then uses all their energy to stay warm and then they don't have any energy left to eat.

• Continue to maintain their normal breathing patterns. When babies have less energy, because they are using it to stay warm, they have less energy to breathe and so sometimes they need to go back on breathing support or they have more pauses in their breathing, also called apneas.