Environmental humidity for premature neonates

  • Introduction

    Infants born at <30 weeks gestation have an immature epidermis and stratum corneum and are at an increased risk of transepidermal water loss (TEWL).  The use of environmental humidity assists to reduce TEWL and in turn supports temperature regulation, fluid and electrolyte management and skin integrity. Prolonged use of high humidity has been shown to delay maturation of the stratum corneum and increase the incidence of TEWL. Therefore, use of environmental humidity outside these criteria should be discussed with the Consultant and/or specialties ie. Dermatology.


    The aim of this guideline is to provide all clinical staff with the criteria, settings and weaning regime required for the provision of environmental humidity for preterm infants.  

    Definition of terms

    • Environmental humidity: The concentration of water vapour in the air. 
    • Hybrid Cot: A hybrid cot operates as an incubator, with the ability to raise the hood and function as an open-system radiant warmer. This cot is beneficial for premature infants who are best suited to being nursed in an incubator, where there is indication for frequent access or surgery that necessitates an ability to provide open-system care.
    • Incubator: Incubators are utilised to provide a controlled, enclosed heated environment to ensure neutral thermoregulation is provided, enabling the infant to be nursed unwrapped. 
    • Servo Control: Heat output is automatically and constantly adjusted according to the programmed set skin temperature, which is continuously measured from the skin temperature probe. This is the preferred mode of applying thermoregulatory assistance to most neonates, but requires close monitoring and assessment of probe site.
    • Transepidermal water loss (TEWL): The evaporative loss of water from the immature epidermal layer of the premature infant’s skin. 


    All neonates <30 weeks gestation AND <2 weeks of age should be nursed in an incubator with environmental humidity and servo control thermoregulation functions.    

    • Four hourly axillary temperatures 
    • On commencing environmental humidity, perform hourly until stable
    • Increase frequency if outside of normothermia
    • An accurate fluid balance should be monitored and recorded.
    • Regular assessment of electrolyte imbalance including serum sodium levels
    • Regular inspection of skin with specific focus on areas of moisture ie behind ears 



    Hybrid Incubator (Baby Leo®)

    A water bag needs to be attached to the humidification system with the connection kit via the leur lock on the rear sensor wall.  On the BabyLeo®, humidity therapy control should be set manually in the therapy bar (see table below).

    How to set up humidity


    There is no evidence to support humidity higher than 80% or the continuation of humidity past day 14 of life. Practice outside these parameters should be discussed with the consultant.

    After successful staged reductions, environmental humidity can then be ceased after 2 weeks of life, as the epidermis will then have matured to act as an effective barrier.  The table below demonstrates the commencing and weaning process for humidification.  

    Day of Life Environmental Humidity (%)
    1-7 80%
    8 75%
    9 70%
    10 65%
    11 60%
    12 55%
    13 50%
    14 45%
    15 CEASE


    Environmental humidity is an order, and observations are documented in flowsheets.

    • Hourly set and actual environmental humidity levels (%)
    • Hourly set and actual servo control temperature as well as documentation about location of servo probe
    • Four hourly axillary temperatures  

    Nursing Care 

    • Nursing staff should take care to check the position of the probe site at the start of the shift, change the position with cares to check for pressure areas. This will ensure that servo control runs without causing problems with temperature instability due to incorrect or invalid temperatures being monitored.
    • Take care to circumvent excess rain-out by wiping the inside of the incubator with a dry cloth.
    • On the hybrid cots there is a clear view button which can be utilised to reduce condensation on the inside of the hood.
    • All hybrid cots providing humidity should be changed every 7 daysas humidification significantly increases microbial growth
    • Change linen every 24-48hrs 
    • Once humidification has been ceased, change hybrid cot, to prevent microbial build up.
    • Cleaning staff need to know whether humidification has been run when using the hybrid cot. Nursing staff should put a sign on the incubator when moving to the cleaning room so that additional cleaning can be undertaken appropriately

    Special Considerations

    • Minimise the opening of doors so that humidity inside incubator remains constant.
    • The hybrid cots have an “air curtain” which can be enhanced using the ‘touch time’ setting to minimise heat lost while portholes open.
    • It is still important to consider clustering cares and minimal handling for all preterm infants.

    Family Care

    • The requirement of environmental humidity in care of a neonate who is haemodynamically stable does not exclude them from participating in skin-to-skin care (SSC). The potential increase in TEWL during SSC is minimal and transpires to negligible clinical importance. Ensure families understand the rationale for environmental humidity and facilitate and encourage interaction with their newborn where able. 
    • Families should be encouraged to participate in performing cares and positive neurodevelopmental interactions such as hand hugs, reading and singing regardless of humidification.


    Skin-to-Skin Care for the Newborn

    Evidence table

    View the Environmental humidity for premature neonates evidence table

    Please remember to read the disclaimer

    The development of this nursing guideline was coordinated by Julia McKeown, RN/RM, Butterfly Ward, and approved by the Nursing Clinical Effectiveness Committee. Updated August 2023.