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.

• 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.