Reviewed April 2014, next review April 2017

Explaining premature birth - risks and causes

Gestational age and medical needs

As soon as your baby is born, the healthcare team will decide what level of care he needs. His health will often depend on how prematurely he was born. The chart below gives a very rough guide to how different ages of gestation could affect your baby.

When you see your premature baby for the first time, it's only natural to feel daunted. He's smaller, frailer and far more vulnerable than you were expecting and will need special care to help him overcome his early start in life.

You may also be feeling exhausted, shocked and scared about what the future may hold, so try to stay calm and have faith in the healthcare team.

Your baby's health, and the treatment he needs, will depend on many factors, including his condition immediately after birth.

What kind of care will my baby need?

Your baby's care will depend on how many weeks old he is at the time of delivery.


Near-term (34-36 weeks)

At this stage your baby is less likely to have severe breathing problems, but is still at risk of problems with blood sugar levels, blood pressure and infection, and may not be able to breast or bottle-feed.



Moderate (32-33 weeks)

At this stage your baby will still need specialised care, and may have low blood sugar and mild breathing problems, but his lungs will be much more mature. However, he will still be at risk of hypothermia, low blood pressure and infection.


Very preterm (28-32 weeks)

At this age, your baby will be susceptible to the same conditions as younger babies - but because he is more developed, the risk is lower.

He is still likely to need support with breathing, and is at risk of hypothermia, low blood sugar and infection, but he is less likely to become severely ill.


Extreme (less than 28 weeks)

At this age, your baby will be transferred to the neonatal intensive care unit after delivery if there isn't one in your hospital.

He will be at high risk of having problems with breathing, as his lungs will not yet be mature enough to breathe independently. He will need to be kept very warm to avoid hypothermia, and will need to be given dextrose to prevent low blood sugar. He will be at high risk of low blood pressure and infection.

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Levels of care

Special care baby unit (SCBU) 

Also called the special care baby unit (SCBU, pronounced 'skaboo') or special care unit (SCU), these provide the most simple level of care for babies in their local area and stabilise a baby's condition before transferring him to another unit or provide emergency care if necessary. They may also provide some high-dependency services. They receive babies from other units once they are well enough to be cared for there.

Local neonatal unit (LNU)

Local neonatal units (LNUs) provide special care for babies in their local area, except for those who are very unwell and need complex or longer-term intensive care. The majority of babies over 27 weeks of gestation will usually receive their full care, including short periods of intensive care, within their LNU.

Neonatal intensive care units (NICU)

These specialist units have the facilities to care for critically ill premature babies. Babies will be transferred here from around the country to access the specialised expertise that they offer. They provide the whole range of medical neonatal care for their local population, along with additional care for babies and their families referred from the neonatal network.

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How your premature baby could look

Premature newborn (24-28 weeks) Premature newborn (29-35 weeks) Premature newborn (35-37 weeks)
24-28 weeks

Weight: 1-3.5lb (450-1600g)

Length: 10-13in (25-33cm)

At this stage, your baby will be very thin, with fragile red skin covered with downy hair (lanugo). His head will look large, he will have soft skull bones, and a small face with a pointed chin and eyes fused shut.

29-34 weeks

Weight: 2-5.5lb (1-2.5kg)

Length: 12-14in (30-35cm)

Your baby will still be quite thin, and his skin will be slightly translucent and still covered in downy hair. In girls you may see tiny nipples. He may move quite vigorously and grasp your finger, and may be able to suck or lick, but he won't be ready to feed on his own.

35-37 weeks

Weight: 3.5-7lb (1.6-3.4kg)

Length: 15-18in (38-45cm)

By this stage, your baby will be much more robust and will look more like what you'd expect a term baby to look like. He may still be quite thin, with some hair, and he may still need extra help with feeding and breathing and staying warm.

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The causes and problems of premature birth

Your premature baby:

You can also read about


WHO (2012) Preterm birth, Fact sheet N 363, The World Health Organisation, November 2012

NHS and Department of Health (2009) Toolkit for high quality neonatal services

Henderson C, Macdonald S (2004) Mayes Midwifery, A textbook for midwives (13th edition), Balliere Tindall



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What kind of care will my baby need?

Levels of care

How your newborn premature baby could look

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Feedback on health information


'Our little girl was born at 23 weeks and five days. She was in a very sorry state. But the very bumpy ride that we had has been countered by the fact that she's perfect, and there isn't a problem - except she's not much good at maths! I know how lucky we are.'




In 1992 the UK changed the definition of preterm live birth (as opposed to miscarriage) from 28 weeks to 24 weeks. This reflects the improved survival rates of babies at 24-28 weeks. In some countries, it is as low as 20 weeks.