Antenatal Corticosteroid Regimen for Preterm Delivery
The recommended regimen is betamethasone 12 mg intramuscularly as two doses given 24 hours apart for pregnant women at risk of preterm delivery. 1, 2
Standard Dosing Protocol
Betamethasone 12 mg IM × 2 doses, 24 hours apart is the evidence-based standard regimen endorsed by both the Society for Maternal-Fetal Medicine and the American College of Obstetricians and Gynecologists. 1, 2
Gestational Age-Specific Recommendations
For 24 0/7 to 34 6/7 weeks gestation:
- Administer betamethasone 12 mg IM × 2 doses, 24 hours apart, to all women at high risk of preterm delivery within 7 days 2, 3
- This represents a GRADE 1A recommendation with high-certainty evidence 1, 2
For 34 0/7 to 36 6/7 weeks gestation (late preterm):
- Offer betamethasone 12 mg IM × 2 doses, 24 hours apart, to women with singleton pregnancies at high risk of delivery within 7 days and before 37 weeks 1
- High-risk criteria include: preterm labor with cervical dilation ≥3 cm or ≥75% effacement, spontaneous rupture of membranes, or anticipated delivery for maternal/fetal indications (e.g., preeclampsia) 4
Clinical Benefits by Outcome
Respiratory outcomes:
- Reduces respiratory distress syndrome by 29% (RR 0.71) 3
- Decreases need for respiratory support by 20% (11.6% vs 14.4%; RR 0.80) 2, 4
- Reduces severe respiratory morbidity by 33% (8.1% vs 12.1%; RR 0.67) 2, 4
Mortality outcomes:
Neurologic outcomes:
- Probably reduces intraventricular hemorrhage by 42% (RR 0.58) 3
- Probably reduces developmental delay in childhood by 49% (RR 0.51) 3
Critical Contraindications
Absolute contraindication:
- Do NOT administer to pregnant patients with pregestational diabetes mellitus due to significantly increased risk of neonatal hypoglycemia 1, 4
Relative contraindication:
Timing Considerations
Optimal benefit window:
- Maximum benefit occurs when delivery happens 24 hours to 7 days after administration 2
- Benefits extend beyond 7 days but are reduced 5
Single course only:
- Administer only one course of antenatal corticosteroids 2, 6
- Routine repeat or "rescue" courses are not recommended for the standard gestational age range 2, 6
- Repeat courses may be considered in special circumstances for women who remain undelivered beyond 7 days and are at continued high risk, though evidence is limited 5
Special Populations
May consider administration in select cases (GRADE 2C):
- Multiple gestations reduced to singleton on or after 14 0/7 weeks 1, 4
- Fetal anomalies 1, 4
- Expected delivery in <12 hours 1, 4
Microcystic congenital pulmonary airway malformation with hydrops:
- Use betamethasone 12.5 mg IM every 24 hours for 2 doses 7
Maternal Safety Profile
Maternal outcomes show:
- Little to no difference in maternal death (RR 1.19) 3
- Little to no difference in chorioamnionitis (RR 0.86) 3
- Little to no difference in endometritis (RR 1.14) 3
- Little to no effect on cesarean birth rate (RR 1.03) 4
Neonatal Monitoring Requirements
Hypoglycemia surveillance:
- Neonatal hypoglycemia is more common with betamethasone but typically mild and self-limited 2, 7, 4
- 93% of hypoglycemia cases resolve within 24 hours 2, 7
- Monitor blood glucose in all exposed neonates 2, 7
Common Pitfalls to Avoid
Avoid administering when:
- Delivery is unlikely before 37 weeks (leads to unnecessary exposure) 1
- Patient has pregestational diabetes (increases neonatal hypoglycemia risk) 1
- Multiple courses are given routinely without specific indication 2, 6
Ensure proper timing:
- Administer when delivery is anticipated within 7 days for maximum benefit 1, 2
- Do not delay necessary delivery to complete the 24-hour dosing interval if maternal or fetal compromise exists 6
Patient Counseling
Patients must be counseled about: