What is premature or preterm birth?

Pregnancy lasts an average of 40 weeks (usually between 38 and 42 weeks). A premature or preterm birth is when a baby is born before 37 weeks. So a baby born at 36 weeks and 6 days is officially premature.

The degree of prematurity is often described by gestational age as:

• extremely premature – less than 28 weeks
• very premature – 28-32 weeks
• moderately premature – 32-34 weeks
• late preterm – 34-37 weeks.

Term babies are those born from 37 weeks.

Gestational age

Gestational age is the length of time your baby has been developing in your uterus. It’s calculated from the first day of your last period.

Exact gestational age is important because the more premature babies are, the less developed they are. And this means that they usually need more medical support for their lungs, hearts, tummy and bowels, temperature control and feeding.

For example, most babies who are born earlier than 32 weeks of pregnancy need help with breathing. They’re usually cared for in a neonatal intensive care unit (NICU). If they’re more developed, they might be cared for in a special care nursery.

Low birth weight

Babies can be both premature and have low birth weight.

Low birth weight is when a baby’s weight is much lower than what’s expected for their gestational age.

Low birth weight can happen because premature babies are born before they get the chance to put on weight in the last weeks or months of pregnancy. These babies have low birth weight, but their development is usually appropriate for their gestational age.

Premature birth risk factors

In about half of all premature births, it isn’t known why the premature birth happens.

The following factors increase the likelihood of a premature birth:

• a previous premature birth
• some conditions of the uterus or cervix, like fibroids or a weakened cervix
• a multiple pregnancy – twins or more
• a maternal condition that means the birth needs to be brought on quickly for the safety of mother and baby – for example, pre-eclampsia
• conditions like diabetes and high blood pressure
• other long-term health conditions.

There are also other factors that are associated with premature birth. These include:

• smoking, vaping or alcohol and other drug use
• not enough maternal nutrition
• too much physical activity
• too much stress
• anxiety or depression
• obesity, overweight or underweight
• lack of regular pregnancy care
• age – being under 17 years or over 35 years.

How to minimise the risk of premature birth

The best way to make sure your pregnancy goes well is to go to your regular antenatal appointments and follow your doctor’s or midwife’s advice about:

• not smoking or vaping, not drinking alcohol and not taking other drugs
• eating well and gaining the recommended weight
• doing the recommended amount of physical activity
• managing stress, depression and anxiety.

Even if you follow all the pregnancy advice, you might still have a premature birth. But if you look after yourself, you’ll have done the very best you can for your baby. If you think you might be at risk of premature birth, talk to your doctor or another health professional.

Women who smoke or vape during pregnancy have a higher risk of having a baby with low birth weight and of having a premature birth, miscarriage or stillbirth. Quitting, even just during pregnancy, will reduce the risk. If you need help to quit, talk to your midwife or doctor or call Quitline on 137 848.

Signs of premature labour or health problems

Contact your midwife, doctor or hospital straight away if you notice one or more labour signs.

Also call your midwife, doctor or hospital as soon as possible if you notice any serious pregnancy health problems. It might be that you feel that something ‘just isn’t right’ or you might feel very unwell, even though you don’t have any serious signs or symptoms. If this happens, it’s still important to get checked out, so that you can get treatment as soon as possible.

If you’re in premature labour, the sooner you see a midwife or doctor the better. Some premature labours can be stopped or delayed. If your baby is growing well and getting everything they need from your body, the longer your baby can stay in your womb, the better.

Sometimes you might know you’re going to have your baby early, so you can ask your health professionals about how to prepare for premature birth.

Where premature babies are born

You’ll most likely need to give birth in a standard birthing suite at a public hospital or private hospital, rather than at home or at a birth centre.

If your baby or babies will be born very early – 32 weeks or earlier – you’ll probably need to give birth in a public hospital with a NICU.

Hospitals with NICUs are usually in bigger cities. If you live in a regional, rural or remote area, you might have to go to a city hospital before the birth.

If your baby is born at a hospital without a NICU and needs to go to one, the hospital will use a specialised baby transport service to take your baby to a NICU. This might be by road or air, depending on where you are and how far you are from a NICU. This service is like a mobile NICU. It’s staffed with a nurse and doctor who specialise in caring for and transporting sick and premature babies.

You or your partner might be able to travel with your baby in the specialised baby transport service. If you aren’t well enough to travel with your baby, you might be able to transfer to the hospital’s maternity unit or accommodation after the birth. Most hospitals with NICUs have accommodation, but this is limited and usually available only for regional or remote parents while their baby is in the NICU.

How premature babies look

Your premature baby’s appearance depends quite a lot on how premature your baby is.

When a baby is born at 34-37 weeks of gestation (late preterm), they usually look like a small term baby.

As a baby’s gestational age at birth decreases, their weight and size generally decrease too.

Extremely premature babies – for example, those born at 24 weeks of gestation – are very small and fit snugly into an adult hand. Their skin might be fragile, shiny, translucent or even red. Their eyelids might be fused shut.

As these tiny babies grow, parents can watch the developmental changes in their baby’s appearance, movement and ability to interact with their world.

Premature baby survival and development

In Australia, most premature babies survive. And survival rates keep getting better as medical knowledge gets better.

Survival is affected by how premature a baby is. The more mature a baby is, the more likely they are to survive. Babies are also more likely to survive when they’re given the special care and equipment they need. For example, babies born after 23 weeks have a higher than 50% chance of survival if they’re born in a specialist maternity centre with a NICU.

Most premature babies go on to develop like babies born at term. The longer your baby’s gestation, the less likely it is that they’ll have health or developmental concerns:

• Late preterm babies have a very small chance of health or development concerns compared with term babies.
• Moderately or very premature babies have a higher chance of health or development concerns compared with late preterm babies.
• Extremely premature babies have the highest chance of health and developmental concerns. But even in extremely premature babies, severe health and developmental concerns are quite uncommon.

Premature babies and their parents might have an unexpected and sometimes stressful start to their life together. But with expert care, support and guidance, the early challenges can often be managed and most children develop well.