Antenatal Corticosteroids to Reduce Neonatal Morbidity and Mortality
Overview
A single course of maternal antenatal corticosteroids (ACS) before anticipated preterm birth is one of the most effective interventions in obstetrics for improving neonatal outcome. A course given within seven days prior to preterm birth reduces perinatal and neonatal death and respiratory distress syndrome (RDS) (Grade A). GTG 74 supersedes GTG 7 and supplements NICE NG25 (Preterm labour and birth).
Gestational Window and Indications
- Offer ACS between 24+0 and 34+6 weeks' gestation when imminent preterm birth is anticipated — established preterm labour, PPROM, or planned preterm birth (Grade A).
- Offer ACS to women with PPROM, who are at increased risk of preterm birth (Grade A).
- Twins and triplets: offer targeted ACS for anticipated early birth in line with singleton recommendations (Grade D).
- Birth should never be delayed to complete an ACS course if the indication for birth is itself threatening maternal or fetal health (Good Practice Point).
- Planned caesarean at 37+0–38+6 weeks: discuss risks/benefits with the woman rather than offering ACS routinely. ACS may cut neonatal unit admission for respiratory morbidity, but effect on RDS/transient tachypnoea is uncertain, and ACS carries risk of neonatal harm (hypoglycaemia, possible developmental delay) (Grade B).
Drug Regimen
- Betamethasone 12 mg intramuscularly, two doses 24 hours apart (total 24 mg) — first-line agent.
- Dexamethasone 6 mg intramuscularly, four doses 12 hours apart (total 24 mg) — alternative where betamethasone is unavailable.
Timing of Effect
- Maximal benefit (reduced perinatal/neonatal death and RDS) is seen when the full course is completed within 7 days before birth (Grade A).
- Reduction in neonatal death is still seen when the first dose is given within 48 hours before birth (Grade D).
- Benefit is also seen when the first dose is given within 24 hours of birth — ACS should still be administered even if birth is expected within this window, since even a partial/incomplete course confers benefit (Grade D).
Repeat and Rescue Courses
- Routine repeat courses are not recommended — a single course is standard practice.
- A single rescue course (repeating the same regimen) may be considered with caution only where the original course was given at less than 26+0 weeks' gestation and a new obstetric indication for imminent preterm birth has since arisen. Senior obstetric opinion should be sought; weigh the interval since the original course, the likelihood of birth within 48 hours, and the gestation at first course.
- Courses beyond a single rescue dose are associated with concerns about reduced birthweight and possible neurodevelopmental effects, and should be avoided outside this specific scenario.
High-Yield Exam Points
- Core gestational window for offering ACS: 24+0–34+6 weeks with anticipated imminent preterm birth (Grade A) — the single most testable fact from this guideline.
- Standard regimens: betamethasone 12 mg IM × 2 doses, 24h apart or dexamethasone 6 mg IM × 4 doses, 12h apart — both total 24 mg.
- Maximal benefit within 7 days of birth; still give if birth is expected within 24–48 hours — partial courses are not futile.
- 37+0–38+6 weeks elective caesarean: shared decision-making, not routine — uncertain RDS/TTN benefit, real risk of neonatal hypoglycaemia.
- A rescue course is only considered if the first course was <26+0 weeks and a new indication for imminent birth arises later — otherwise a single course is the rule.
- Never delay clinically indicated birth to "complete" a steroid course.
Source: RCOG Green-top Guideline No. 74 (Published February 2022 (replaces archived Green-top Guideline No. 7, Oct 2010); page last reviewed 5 June 2025)
Read the original on rcog.org.uk
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