Premature Birth

Key Points:

1. Only 5% of babies are born on their due date; around 8% are born prematurely in Australia, mostly between 32-36 weeks.
2. Babies born before 37 weeks are considered premature; a full-term pregnancy is between 38-42 weeks.
3. Survival rates vary: about 2/3 born at 24 weeks admitted to NICU survive, while 98% born at 30 weeks gestation survive.
4. Prevention strategies involve discussing risks with maternity care providers, considering progesterone supplements, and cervical cerclage in certain cases.

What does it mean for me and my baby?

Most of us have heard of babies being born before they are due. But like many situations, until we’ve had personal experience we can’t fully appreciate its impact. Having a baby before their expected date can come as a real shock to parents who may have not even considered premature birth as a possibility. But we know that only around 5% of babies come on their due date and the remainder before or after they’re expected. 

Currently in Australia every year, around 8% of babies are born prematurely and of these, most are born somewhere between 32-36 weeks gestation.

What does Premature Mean?

The definition of prematurity varies according to the source. Generally babies are said to be premature if they are born before 37 weeks of gestation. A full term pregnancy lasts between 38-42 weeks.

Advances in our understanding and care of premature babies have significantly improved health outcomes for premature babies. But unfortunately, some babies are born far too early and are unable to survive.

Depending on the Length of Gestation

A baby may be:

• Late preterm – if they are born between 34 and 36 weeks.
• Moderately preterm – if they are born between 32 and 34 weeks.
• Very preterm – if they are born at less than 32 weeks.
• Extremely preterm – if they are born at or before 25 weeks.

Every Little Person is an Individual

Not all premature babies will be at the same stage of growth and development. Although babies may share the same gestational age, there are lots of other factors which determine their size and maturity.

A baby’s birth weight as well as their gestational age, makes a real difference in their chances of survival.

What are the Odds?

Statistically

• Around 2/3 of babies who are born at 24 weeks and who are admitted to a neonatal intensive care unit will survive and be discharged home.
• Around 98% of babies who are born at 30 weeks gestation will survive.

Some hospitals are better equipped than others to care for premature babies. Very premature or sick babies who are born in regional or smaller hospitals are often transferred to larger metropolitan hospitals with a Neonatal Intensive Care Unit (NICU). Once the baby is stable and gaining weight, they can be transferred back to the family’s closest hospital until they’re ready for discharge home.

What Causes Prematurity?

There are a range of possibilities but in many cases, there is no real cause. A mother may go into premature labour for no apparent reason.  It’s difficult to predict with certainty if a mother is going to have her baby before it is due.

However, there are a range of risk factors which increase the possibility of prematurity:

• Twins, triplets or other multiple births.
• High blood pressure e.g. pre eclampsia.
• Maternal infection or illness.
• Physical trauma.
• Previous history of premature birth.
• Multiple pregnancies or terminations of pregnancy.
• Smoking or using illicit drugs.
• Diabetes –Type 1 or 2 or gestational diabetes.
• Less than six months between pregnancies.
• Having conceived with fertility assistance e.g. IVF.
• Family stress or emotional trauma.
• Being underweight or having a low BMI before conceiving.
• Previous surgery or problems with the uterus, cervix or vagina.

Can Premature Labour be Stopped?

Sometimes treatment for stopping labour is tried, but this depends on a few factors. If a mother is in advanced and progressive labour then halting her labour can be very difficult.

The benefits and risks of continuing the pregnancy are weighed up carefully. As a rule, for every extra day a baby stays in the uterus it is better off. But if the baby is stressed, isn’t growing or the mother is at risk,  then labour may be a preferable option, even if it means the baby will be born early.

Nifedipine tablets may be given to a mother to help slow or stop her labour.   Nifedipine is a smooth muscle relaxant and helps to stop the uterus contracting.  

Another option for women at less than 30 weeks gestation is treatment with magnesium sulphate. This is an intravenous medication, given over 24 hours, which improves the chances of the baby surviving.

Steroid injections can be given to a mother to improve her baby’s lung maturity and boost its chances of survival. Every maternity hospital has its own protocol on steroid use, but as a rule, most mothers are given the option of having a course of steroid injections between 24-34 weeks if they are in labour. Two injections are given, 12 hours apart by injection into her leg or arm and they take around 24 hours to be effective.  

What can I expect if my Baby is Premature?

• If your baby is born before 36 weeks gestation, they are likely to be admitted to a neonatal unit.
• If they are born before 30 weeks gestation or they need help with their breathing, they are likely to be admitted to a Neonatal Intensive Care Unit (NICU).
• If your baby is larger and doesn’t have any problems with their breathing, they may be admitted to a special care unit.

Premature Babies look different to babies born at term  

They may:

• Be generally smaller but their head looks disproportionately large.
• Have finer facial features with less fat “filling out” their face.
• Have tiny hands, feet and limbs.
• Veins may be visible underneath their skin.
• Have a big belly.
• Be covered in fine hair – this is called lanugo.
• Be very sleepy and not cry much.
• They may not open their eyes.
• Not have the usual reflexes like sucking and swallowing.
• Have laboured or irregular breathing patterns.

Complications of Prematurity

Some babies defy all odds and progress very well although they were born early. And some struggle more than is fair.

• Lung disease. Some babies are born so early they can’t breathe on their own and need the help of a ventilator.
• Cardiac (heart) issues.
• Apnoea episodes. This is when the baby “forgets” to breathe for a short window of time. Apnoea is generally caused by brain immaturity.
• Bradycardic episodes. This is when the baby’s heart rate slows as a result of a drop in their oxygen from apnoea.
• Jaundice – this is when the baby’s skin becomes yellow. Jaundice is caused by liver immaturity and is a byproduct of red cell breakdown.
• Maintaining their temperature. This is why premature babies are often placed in an incubator which maintains an even temperature and air flow.
• Problems with feeding and sucking.
• Problems with maintaining an even blood sugar.

Long Term Problems Caused by Prematurity

Disabilities really depend on how premature the baby was, their birth weight and how they progressed in the early neonatal period. Complications after birth e.g. infection or surgery can significantly affect the baby’s prognosis.

Around 1/3 of babies born at 24 weeks gestation will develop a disability. This is commonly in the areas of their intellectual and physical growth. Eyesight, development, speech and language and gross motor skills are the more commonly affected areas. Sometimes more minor disabilities don’t become obvious until the child starts school and they are compared against other children of the same age and gender.

Early detection of problems is key to best outcomes.

While not all premature babies experience complications, being born too early can cause short-term and long-term health problems. Generally, the earlier a baby is born, the higher the risk of complications. Birth weight is important too as a heavier birth weight can provide extra protection.

What can I do to Prevent Premature Labour?

It can be very hard to predict or prevent premature labour. Some researchers believe the baby regulates the timing of their birth by secreting proteins which initiate the mother’s labour.

If you feel you are at increased risk of having your baby early, there are a few things you can try. Just remember, there are no guarantees, babies have a tendency to be born when they are ready.  The exact cause for the onset of labour isn’t clear.

• Speak with your maternity care provider about your individual risks.
• Progesterone supplements can reduce the risk of premature labour in some women.
• Cervical suture, also known as cervical cerclage is occasionally recommended. This is a surgical procedure and can be done from 14 weeks of pregnancy to strengthen a vulnerable cervix. Cervical cerclage is often done for women who know they have a short cervix, or a cervical weakness or who have experienced premature labour in the past.  

References

• Better Health: Premature Babies 
• Mayo Clinic: Premature Birth 
• Science Daily

This article was written for Nourish by Jane Barry, midwife and child health nurse.