What is the recommended dose of Betamethasone (Betamethasone) or Dexamethasone (Dexamethasone) for preventing Respiratory Distress Syndrome (RDS) in preterm infants 48 hours before delivery at 24-34 weeks of gestational age (AOG - Age Of Gestation)?

Recommended Dosing for Prevention of RDS

For pregnancies at 24-34 weeks gestation at risk of preterm delivery, administer betamethasone 12 mg intramuscularly as two doses given 24 hours apart. 1

Standard Dosing Protocol

Betamethasone (Preferred Agent)

• Dose: 12 mg intramuscularly
• Frequency: Two doses, 24 hours apart
• Timing: Administer when delivery is anticipated within 7 days
• Gestational age range: 24 0/7 to 34 6/7 weeks 1

This regimen is the evidence-based standard endorsed by the Society for Maternal-Fetal Medicine (SMFM) with GRADE 1A recommendation strength. 1

Dexamethasone (Alternative)

While the guidelines primarily recommend betamethasone, dexamethasone can be used as an alternative agent. However, intramuscular administration is essential - oral dexamethasone should be avoided due to significantly increased neonatal morbidity. 2

• If using dexamethasone: 6 mg intramuscularly every 12 hours for 4 doses 3, 2
• Critical caveat: Oral dexamethasone is associated with significantly higher rates of neonatal sepsis (15.9% vs 1.6%, P=0.009) and intraventricular hemorrhage (15.9% vs 3.3%, P=0.03) compared to intramuscular administration and should NOT be used clinically. 2

Clinical Benefits

Betamethasone administration substantially reduces:

• Need for respiratory support (11.6% vs 14.4%; RR 0.80) 1
• Severe respiratory morbidity (8.1% vs 12.1%; RR 0.67) 1
• Death, respiratory distress syndrome, intraventricular hemorrhage, and sepsis 1

The benefits are most pronounced in infants delivered between 28-32 weeks gestation, though effectiveness extends through 34 weeks. 4

Extended Gestational Age Considerations (34-36 6/7 Weeks)

For late preterm deliveries (34 0/7 to 36 6/7 weeks):

• Same dosing regimen: betamethasone 12 mg intramuscularly, two doses 24 hours apart 1
• Only administer if: High risk of delivery within next 7 days AND before 37 weeks 1
• This reduces respiratory morbidities and NICU admissions in late preterm neonates 5

Important Contraindications and Cautions

Do NOT administer antenatal corticosteroids in:

• Pregnant patients with pregestational diabetes mellitus - significantly increases risk of neonatal hypoglycemia 1
• Patients with low likelihood of delivery before 37 weeks 1

Common Pitfalls to Avoid

1. Avoid oral dexamethasone: Despite convenience, it increases neonatal sepsis and intraventricular hemorrhage without demonstrable benefit over intramuscular administration 2

2. Timing matters: Maximum benefit occurs when delivery happens 24 hours to 7 days after administration 1

3. Single course only: Administer one complete course; routine repeat or "rescue" courses are not recommended in this gestational age range 1

4. Neonatal hypoglycemia monitoring: While more common with betamethasone (compared to placebo), 93% of cases resolve within 24 hours and are mild and self-limited 1

Dosing Interval Considerations

Recent research suggests that a 12-hour interval between betamethasone doses may be considered as an alternative to the standard 24-hour interval, though the 24-hour interval remains the guideline-recommended standard. 6 The most critical factor is completing both doses rather than the specific interval between them. 6