Antenatal Steroid Therapy

1. INTRODUCTION

• Definition: The administration of corticosteroids to pregnant women at risk of preterm delivery.
• Goal: To accelerate fetal organ maturation (specifically lungs), reduce neonatal morbidity/mortality, and improve survival.
• Status: Considered one of the most effective interventions in perinatal medicine.

2. MECHANISM OF ACTION

• Fetal Lung Maturation:
  • Stimulates Type II Pneumocytes to increase surfactant production.
  • Increases lung compliance and fluid clearance.
  • Significantly reduces the risk of Respiratory Distress Syndrome (RDS).
• Systemic Maturation:
  • Stabilizes germinal matrix vasculature (reduces Intraventricular Hemorrhage - IVH).
  • Accelerates gut maturation (reduces Necrotizing Enterocolitis - NEC).
  • Reduces risk of systemic infections in the neonate.

3. INDICATIONS

Antenatal steroids are indicated when there is a risk of preterm birth, generally between 24 and 34 weeks of gestation.

A. Specific Clinical Scenarios

1. Threatened Preterm Labor: Women presenting with regular contractions and cervical changes before 34 weeks.
2. Preterm Premature Rupture of Membranes (PPROM): To induce maturation before inevitable delivery.
3. Elective Early Delivery: When early delivery is required for maternal/fetal indications (e.g., Severe Preeclampsia, severe IUGR).
4. Multiple Gestations: Twins/Triplets at risk of early birth.
5. Extended Window:
   • Periviable: Can be considered as early as 23 weeks.
   • Late Preterm: Can be considered up to 36+6 weeks in selected cases (ALPS trial era).

4. REGIMENS

The preferred corticosteroids are those that cross the placenta in active form (lack of placental metabolism). Both are equally effective.

Drug	Dose	Frequency	Total Duration	Route
Betamethasone	12 mg	Every 24 hours	2 Doses	IM
Dexamethasone	6 mg	Every 12 hours	4 Doses	IM

• Choice: Depends on availability and local guidelines.

5. REPEAT COURSES (Rescue Therapy)

Routine multiple courses are not recommended due to concerns about fetal growth (brain/somatic).

• Single Rescue Course: May be considered if:
  1. The patient remains at risk of preterm birth.
  2. It has been >14 days (2 weeks) since the initial course.
  3. Gestational age is <34 weeks.
• Timing: Can be given as early as 7 days after the prior dose if clinically indicated.

6. BENEFITS (Evidence Base)

Administration of a complete course is associated with significant reductions in:

1. Neonatal Mortality (Death).
2. Respiratory Distress Syndrome (RDS).
3. Intraventricular Hemorrhage (IVH).
4. Necrotizing Enterocolitis (NEC).
5. Systemic Infections.
6. Neurodevelopment: Associated with improved long-term neurological outcomes.

7. LIMITATIONS & CONTRAINDICATIONS

• Gestational Age limit: Not routinely recommended after 37 weeks.
• Maternal Infection: Use with caution in active maternal infection (e.g., chorioamnionitis, tuberculosis) as it may mask signs of sepsis.
• Long-term Safety: Generally safe, but ongoing surveillance of neurodevelopmental outcomes is advised.