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Steroid therapy for preterm birth

Key points about steroid therapy for preterm birth

If a baby is at risk of being born too early (before 35 weeks of pregnancy), giving the mother steroid therapy before the birth can help her unborn baby's lungs to develop more quickly.
This reduces the risk of serious complications or the newborn dying.
Steroid therapy is usually given as betamethasone injection (two doses, 24 hours apart).

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A short course of steroid injections may be offered to you to help your baby if there's a chance that you may give birth early (before 35 weeks of pregnancy). Steroids help develop your baby’s lungs. Read more about premature labour and birth.

Premature babies may have some health problems, which tend to be more serious the earlier they're born. Giving you steroid injections shortly before your baby is born reduces the risk of them having some serious complications including:

breathing problems
bleeding in their brain
inflammation of their bowel.

Steroid therapy is usually offered from 24 to 35 weeks of pregnancy. It's unlikely to be offered after 35 weeks as your baby’s lungs are likely to be ready for breathing on their own so it's not needed.

The steroid, betamethasone is given as an injection into a muscle, usually in your thigh or upper arm.

A course is 2 injections, given 24 hours apart.
Repeat doses may be given after 7 days from the first course of steroids if your baby is at risk of being born very early, depending on the gestation (weeks of pregnancy) and other factors.

Timing

Steroids are of most benefit if the last dose is given to you between 24 hours and 1 week before the birth of your baby.

There may still be some benefit even if your baby is born within 24 hours of the first dose.
Steroids are not as effective if your baby is born more than 7 days after the treatment.

Even if you're at risk of giving birth early, you won’t be given steroids unless you're likely to give birth in the next 7 days.

A course of steroids is safe for you and your baby. You may experience some minor side effects, eg, pain at the injection site. For most babies born at 23 to 35 weeks, the benefits of steroids are greater than the risks.

If you're given steroid injections, some babies may have:

a slightly lower birth weight than average
low blood glucose levels after birth that need extra monitoring and management.

Your healthcare team will talk to you about how the risks and benefits of steroids may affect you.

Premature labour

The following links have more information on steroid injections. Be aware that websites from other countries may have information that differs from New Zealand recommendations.

Steroids in pregnancy(external link) Queensland Health, Australia
Corticosteroids in pregnancy to reduce complications from being born prematurely(external link) Royal College of Obstetricians & Gynaecologists, UK
Pregnancy and birth: Before preterm birth – what do steroids do?(external link) National Library of Health, US