Preterm birth and antenatal corticosteroids – making an informed choice

Who is the leaflet for?

• Anyone between 24 and 34 weeks pregnant at higher chance of preterm birth, in preterm labour or waters have broken
• Consideration for below 24 weeks, only after senior counselling
• Anyone who requires early birth as they or their baby are at an increased risk of complications

What is preterm birth?

8 out of 100 (8%) babies in the UK are born less than 37 weeks of pregnancy. This is called preterm (or premature) birth. Late preterm birth is between 32 - 37 weeks, very preterm 28 - 32 weeks, extremely preterm is less than 28 weeks.

Risks of preterm birth

The earlier a baby is born, the higher their chance of health problems including difficulty breathing (respiratory distress syndrome or RDS), difficulty feeding, difficulty maintaining temperature, and neurological problems. There is a higher chance preterm babies will be admitted to the neonatal intensive care unit (NICU). Preterm babies may have long term health issues.

What are corticosteroids?

Corticosteroids are a man-made version of a chemical produced by the body. They are offered as an injection to anyone before 34 weeks that have been identified as having a higher chance of preterm birth within the next week, to reduce complications to the baby. There are some individual cases where steroids may be offered after 34 weeks. Commonly Betamethasone is the drug used, and is given as two injections 12 to 24 hours apart – this is known as a course of steroids.

Benefits of corticosteroids

Corticosteroids reduce your baby’s risk of respiratory distress syndrome, bleeding in the brain, serious infections, and bowel inflammation. Babies born extremely preterm benefit the most. A full course of the two corticosteroid injections will be most effective, however a single dose of steroids increases the chance of survival. Steroids are most effective if given between 24 hours and one week of birth, but there is still some benefit if birth occurs fewer than 24 hours after being given.

Risks of corticosteroids

Steroids are generally thought to be safe. There is no risk to the woman/pregnant person, or their immune system. Babies born after receiving steroids may have low blood sugars, if this happens they will receive care and treatment for this. Some new studies have shown an association between babies born at or after 37 weeks whose mother’s received steroids and an increased chance of special educational needs, lower academic ability and behavioural problems. More research is needed to confirm this.

If you have diabetes and are having antenatal corticosteroids you will require close monitoring of your blood sugar levels.

Speak to a doctor

You may wish to discuss your options about steroids with your obstetrician if you have been identified as having a higher chance of preterm birth before 37 weeks.

References / sources of evidence

Stock, S., Thomson, A. and Papworth, S. (2022). Antenatal corticosteroids to reduce neonatal morbidity and mortality. BJOG: An International Journal of Obstetrics & Gynaecology. doi:10.1111/1471-0528.17027.

Royal college of Obstetricians and Gynaecologists (RCOG) (2022) Corticosteroids in pregnancy to reduce complications from being born prematurely – patient information leaflet Corticosteroids in pregnancy to reduce complications from being born prematurely – patient information leaflet | RCOG (opens in a new tab)

Tommy’s (2021) Preparing your baby for a premature birth Preparing your baby for a premature birth | Tommy's (tommys.org) (opens in a new tab)