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Premature babies

Premature babies are born too early, before they have fully developed in the womb. They often need extra or intensive medical care and support while their organs continue to develop to a point where they can survive without specialist help. Most premature babies go on to have normal healthy lives, but they are at increased risk of medical and development problems than babies who were born at the right time.

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What is a premature baby?

A premature baby is one who is born earlier than expected. Babies are normally born at around 40 weeks of pregnancy. Babies born before 37 weeks are considered premature or preterm.

Babies born at less than 22 weeks of pregnancy (gestation) cannot survive. Those born at less than 28 completed weeks of pregnancy are considered extremely premature, and will be at most risk of complications and medical problems. Those born between 28 and 32 weeks of pregnancy are considered very premature. Babies born between 32 and 37 weeks are considered to be moderate to late premature.

Across the world, more than one in ten babies are born prematurely.

Why are babies born prematurely?

There are many reasons why babies may be born early or factors which may make this more likely. These include:

  • Having more than one baby at a time (multiple pregnancy) - ie twins, triplets, etc.

  • Pre-eclampsia - a condition where the mother has high blood pressure. This may cause early labour or it may be deemed medically safest to deliver the baby early to protect the baby or the mother from the effects of this condition.

  • Early separation of the placenta from the womb - placental abruption.

  • The placenta being situated too low - placenta praevia.

  • Your waters breaking early (preterm prelabour rupture of membranes).

  • A weak cervix which opens too early (cervical insufficiency).

  • Having diabetes or gestational diabetes.

  • A genetic abnormality of the baby.

  • Smoking in pregnancy.

  • Excess use of alcohol in pregnancy or having a baby with fetal alcohol syndrome.

  • Very severe stress.

  • Having an infection (such as a urine infection or a vaginal infection or being generally unwell).

In many cases it is not known why a baby was born early.

See also the separate leaflet called Premature Labour for more information.

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Will my premature baby survive?

Most babies born early in the UK survive and go on to be healthy in childhood. Sadly, some will not survive however, and babies born prematurely may be more likely to have problems with their growth and development. Broadly speaking, the less your baby weighs and the less time they have been in the womb, the lower the chance of survival and the higher the risk of complications.

Survival rates for premature babies vary enormously. It will depend on:

  • The reason for the premature birth.

  • The gestation at the time of birth, ie how premature your baby is.

  • The weight of your baby at birth. Your baby is considered to have:

    • A low birth weight if they weigh less than 2500 g (5 lb)

    • A very low birth weight if they weigh less than 1500 g (3 lb)

    • An extremely low birth weight if they weigh less than 1000 g (2 lb)

Recent research by the pregnancy charity Tommy's found that in the UK:

  • About 8% of births in the UK are preterm. That is around 60,000 babies each year. Of the births that were preterm in the UK:

    • 5% were extremely preterm (before 28 weeks).

    • 11% were very preterm (between 28 and 32 weeks).

    • 85% were moderately preterm (between 32 and 37 weeks).

  • Medical advances mean that we are getting better at treating preterm babies but the chances of survival still depend on the gestational age (week of pregnancy) at the time of birth:

    • Less than 22 weeks is close to zero chance of survival.

    • 22 weeks is around 10%.

    • 24 weeks is around 60%.

    • 27 weeks is around 89%.

    • 31 weeks is around 95%.

    • 34 weeks is equivalent to a baby born at full term.

Also, the earlier the baby is born, the more the chance of complications leading to disability which may be life long. For babies who survive being born extremely early, between 23 and 25 weeks, many will live with moderate or severe disabilities.

Although the earlier the birth, the higher the risk of problems, some extremely premature babies do very well and develop into healthy children. However about 1 in 10 of all premature babies will have a permanent disability such as lung disease, cerebral palsy, blindness or deafness.

One study of 241 children born before 26 weeks of gestation found:

  • 1 in 5 had severe disability (eg, cerebral palsy + not walking, low cognitive scores, blindness, profound deafness).

  • 1 in 4 had moderate disability (eg, cerebral palsy + walking, IQ/cognitive scores in the special needs range, lesser degree of visual or hearing impairment).

  • 1 in 3 had mild disability (defined as low IQ score, squint, or requiring glasses).

  • 1 in 5 had no problems.

Those with moderate disabilities may be delayed in their development and may need some level of support long term. Those with severe disabilities may be completely dependent on parents or carers for life, and may never reach some of the normal developmental milestones.

Care of a premature baby in hospital

The level of intensive care your baby will need depends on how premature they are and whether they have any complications from their early birth. Your baby may need admission to a:

  • Special Care Baby Unit (SCBU). In this type of unit, the baby can be monitored continuously to keep an eye on their breathing, heart rate, etc. They can receive oxygen if needed, or can have phototherapy for jaundice (see below). They may need to be fed from a tube.

  • Local Neonatal Unit (LNU). This can provide even more intensive care for short periods of time.

  • Neonatal Intensive Care Unit (NICU). If your baby is born before 28 weeks, or if they need help with breathing (ventilation) they would be admitted to a NICU. These are more specialist units for the smallest or the most unwell babies, and your baby may need to be transferred to another hospital which has such a unit.

In some neonatal units you can visit your baby at any time; others have more restricted visiting times. In some, there is a place for parents to stay so they can be near their baby. Specialist neonatal nurses and doctors will look after your baby with the help of other health professionals as needed. You will be encouraged to be involved in as much of your baby's care as possible. How much you can do as parents depends on how small and how ill your baby is. You are absolutely central to your baby's care, and the whole team is working towards a time when hopefully you will be looking after the baby without them.

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What are the complications of premature babies?

When babies are born early, their various systems may not yet be ready for life outside the womb. They often need supportive care as these systems develop. Premature babies are also more vulnerable to infections. The following are some of the conditions which are more common in premature babies and which may need treatment in the neonatal unit.

Breathing problems

Premature babies may need some help with breathing as their lungs develop. Your baby might need breathing support with one of the following:

  • Extra oxygen - via tubes placed into each of your baby's nostrils.

  • Continuous positive airway pressure (CPAP) - air and oxygen are passed through a mask or through tubes placed into your baby's nostrils.

  • Ventilation - air and oxygen are delivered directly into your baby's airway (trachea) through a tube.

Lung problems which are more common in premature babies include:

  • Respiratory distress syndrome (RDS). This is very common in extremely premature babies born before 28 weeks and fairly common in those born before 32 weeks. It is due to the lungs not being developed enough to be ready to breathe in air. This is partly due to lack of a substance called surfactant, produced by the lungs, which stops the air spaces from collapsing. An artificial surfactant product can be given to the baby's lungs to help them function better. In some cases this problem can be prevented by giving steroids to the mother before delivery to help the lungs develop more quickly.

  • Chest infections such as pneumonia. Premature babies are more vulnerable to infections. These are treated with antibiotics and help with breathing as above.

  • Apnoea. This means the baby stops breathing from time to time. Premature babies are monitored so that this can be managed if it happens.

  • Pneumothorax. This is a collapsed lung. Air gets into the space between the lung and the chest wall, squeezing the lung so it can't expand properly. It is treated by draining out the air with a needle or tube.

  • Bronchopulmonary dysplasia. This can be a complication of RDS. The lung is scarred or damaged, possibly from previous treatment. It causes longer-lasting breathing problems which may need longer-term treatment.

Heart problems

A condition called patent ductus arteriosus (PDA) is more common in premature babies. When your baby is in the womb, a tube (duct) connects the two blood vessels leaving the heart as the blood does not need to go through the lungs.

The mother's lungs are keeping the baby's blood supplied with oxygen. After birth, however, the blood must go through the lungs, so usually this duct closes soon after birth when it is no longer needed. If this tube does not close up, it can cause problems with the baby's lungs and heart. PDA can be treated with medicines or with an operation.


Jaundice is a yellowing of the skin and of the white part of the eyes. It can occur in any newborn baby (neonatal jaundice), but is more common in premature babies as the liver may be less well developed. The liver usually helps to clear the body of a substance called bilirubin which in higher levels turns the skin yellow and can cause problems. Babies with high levels of bilirubin are treated with phototherapy lamps. Sometimes they need exchange transfusions - replacing their blood with blood which does not have high bilirubin levels.

Brain problems

Bleeding into the brain can be a complication which is more common in very premature babies and those of extremely low birth weight.

Bleeding in the brain may result in an increased pressure from fluid in the brain, called hydrocephalus.

Eye problems

If a baby is born before the eyes have fully developed they may be at risk of sight impairment or loss of vision.

Gut problems

A condition called necrotising enterocolitis is more common in premature babies. A part of the gut (bowel) becomes inflamed and damaged, and the contents of the gut can leak out. This needs rapid treatment, and in some cases an operation.


The immune system of premature babies may not be as well developed, and they can be more vulnerable to infections. Visitors with coughs or colds will be advised to keep away from the neonatal unit, and you are likely to be asked to use a disinfectant gel on your hands when you come in. This is to try to protect these particularly tiny babies from germs.

Temperature control

Premature babies may not yet be able to maintain a normal body temperature. They may not have enough body fat to keep them warm. They may need to be in a special temperature-controlled cot (incubator).

Do premature babies have problems later in life?

Premature babies are more at risk of developmental problems and disorders as they grow up through childhood and beyond. Again, the earlier and the smaller they were born, the more the chance of ongoing health problems. So your baby/child will need regular review and assessment to check up on their development, so that help, treatment and support can be given where it is needed. To work out whether they are developing normally, your baby's developmental or corrected age will be used - ie the age they would have been if they had been born on their due date.

Premature babies are more at risk of the following health conditions:

  • Developmental delay - for example, they may be late to learn to sit, crawl, walk, talk, etc.

  • Cerebral palsy - brain damage causes problems with muscle functions.

  • Learning disability.

  • Speech and language difficulty.

  • Attention deficit hyperactivity disorder (ADHD) and other problems with concentration or hyperactivity.

  • Autism spectrum disorder.

  • Emotional problems.

  • Behavioural problems.

  • Sleep problems.

  • Feeding difficulties.

  • Eyesight problems.

  • Hearing problems.

Lots of premature babies obviously don't have any ongoing problems, particularly those babies who were only a little bit early and had no early medical complications. If your baby was born before 30 weeks of pregnancy then they will be closely monitored for these types of problems.

Also if they were born after 30 weeks of pregnancy but had an early brain problem, such as an infection of the brain or bleed into the brain, their development will be monitored. If any problems are identified, you may be offered further tests, help, support or treatment, depending on the situation.

Parents need support too

It can be very frightening when your baby is born early. Your baby can look so tiny and fragile, and instead of being at home with you they may be attached to tubes in the hospital.

There are lots of sources of support for parents in this new, bewildering and frightening situation. Most importantly, the team looking after your baby will explain to you exactly what is happening to your baby.

As much as possible they will show you how you can look after your baby and be part of the team. They will give you specific information about any conditions your baby may have or any treatment they are giving your baby. It helps to understand what is going on, so do ask them when you don't!

They will also direct you towards other sources of support and information, such as that on the website of charities such as Bliss or others local to your area or country. Make sure you as parents are getting enough sleep, and are eating regularly and are able to talk about your worries. Any brothers or sisters of the new baby will need support and comfort too.

Feeding a premature baby

This is covered in the separate leaflet called Feeding Premature Babies.

When are premature babies allowed to go home?

Your specialist team will be working towards the day you take your baby home. Often there will be a transition stage between being on a special neonatal unit and going home.

During this stage you will be the main carer for your baby, but in a hospital environment where there is support in case of any problems. This can help build up your confidence and skill in looking after your newborn baby.

Before you go home, your specialist team will make sure you know how to feed your baby, how to give any medicines or treatment still required, when you should ask for medical help and how to access it.

Further reading and references

Article history

The information on this page is written and peer reviewed by qualified clinicians.

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