Potent Systemic Corticosteroid Pregnancy: Used intentionally in pregnancy for fetal lung maturation (24–34+6 weeks) — this IS the primary indication. For maternal systemic indications, prednisolone is preferred as it is largely metabolised before reaching the fetus.

Betamethasone (Systemic)

Brand names: Betnesol (IV/IM), Celestone (IM depot)

Adult dose

Dose: Fetal lung maturation (antenatal): 12mg IM, repeat once after 24 hours (two doses total). Inflammatory / immunosuppressive conditions: 0.5–9mg daily oral (as betamethasone sodium phosphate) — doses equivalent to prednisolone × 6.7 (betamethasone 0.75mg ≡ prednisolone 5mg). Intralesional / intra-articular: 6mg/mL depot injection — 0.25–2mL per site.

Route: IM (antenatal/depot) / IV / Oral

Frequency: Two doses 24h apart (antenatal); once to twice daily (systemic)

Max: 24mg total (antenatal course — two 12mg IM doses); systemic dosing individualised

Betamethasone is the preferred corticosteroid for fetal lung maturation (with dexamethasone as alternative) — crosses the placenta without being inactivated (unlike prednisolone, which is 90% metabolised before reaching fetus). Betamethasone 0.75mg ≡ prednisolone 5mg ≡ dexamethasone 0.75mg in anti-inflammatory potency. No mineralocorticoid activity.

Paediatric dose

Dose: 0.075 mg/kg

Route: Oral / IV

Frequency: Once to twice daily

Max: Individualised

BNFc: Anti-inflammatory: 0.075–0.125mg/kg OD or BD (max dose equivalent to prednisolone dose). Seek specialist paediatric endocrinology opinion. Antenatal betamethasone benefits the fetus, not the child directly.

Dose adjustments

Renal

No specific dose adjustment — monitor fluid and electrolytes.

Hepatic

Use with caution in severe hepatic impairment — unlike prednisolone, betamethasone is not significantly inactivated by the placenta or liver first-pass in the same way.

Paediatric weight-based calculator

Patient weight (kg)

Clinical pearls

Antenatal corticosteroids: NICE NG25 recommends betamethasone 12mg IM × 2 doses, 24h apart, for women between 24+0 and 34+6 weeks at risk of preterm delivery — reduces RDS, IVH, and neonatal death
Single course only: repeat courses of antenatal betamethasone associated with reduced birthweight and head circumference — do not give multiple repeat courses routinely
Potency comparison: betamethasone and dexamethasone are equipotent and both cross the placenta — both used for fetal lung maturation; betamethasone 12mg preferred per most UK guidelines
Maternal glucose monitoring: betamethasone causes significant hyperglycaemia for 24–48h post-injection — diabetic mothers require increased insulin monitoring

Contraindications

Systemic infection without antimicrobial cover
Live vaccines
Hypersensitivity to betamethasone

Side effects

Hyperglycaemia
Fluid retention (less than prednisolone — no mineralocorticoid activity)
Adrenal suppression
Osteoporosis (long-term)
Cushing's syndrome features
Immunosuppression
Neonatal hypoglycaemia (if multiple antenatal courses)

Interactions

Rifampicin — CYP3A4 induction; reduces betamethasone efficacy significantly
Phenytoin, carbamazepine — reduce corticosteroid efficacy
Live vaccines — contraindicated at immunosuppressive doses

Monitoring

Blood glucose (24–48h post-injection in diabetic mothers)
Fetal heart rate monitoring after injection
Neonatal blood glucose (newborn of mothers who received antenatal betamethasone)

Reference: BNFc; BNF 90; NICE NG25 (Preterm Labour); Royal College of Obstetricians and Gynaecologists (RCOG) Antenatal Corticosteroids Guideline. Verify against your local formulary and the latest BNF before prescribing.

Curated clinical cross-links plus same-class fallbacks.

Calculators

Drugs

Dexamethasone · Potent Systemic Corticosteroid

Pathways