Dexamethasone Dosing for Preterm Labor
Administer dexamethasone 12 mg intramuscularly every 24 hours for 2 doses (total of 24 mg over 48 hours) to pregnant women at risk of preterm delivery. 1
Standard Dosing Protocol
The recommended regimen is dexamethasone 12 mg intramuscularly, given as two separate doses 24 hours apart. 1 This is an acceptable alternative when betamethasone is unavailable, though betamethasone remains the preferred agent based on guideline recommendations. 1
- The intramuscular route is essential—oral dexamethasone should never be used, as it significantly increases neonatal sepsis (15.9% vs 1.6%) and intraventricular hemorrhage (15.9% vs 3.3%) without demonstrable benefit. 2
- Maximum benefit occurs when delivery happens 24 hours to 7 days after administration. 3
Gestational Age-Specific Recommendations
Early Preterm (24-34 weeks)
- Administer the standard 12 mg intramuscularly every 24 hours for 2 doses to all women at risk of preterm delivery in this gestational age range. 3
- This carries a GRADE 1A recommendation strength from the Society for Maternal-Fetal Medicine. 3
Late Preterm (34 0/7 to 36 6/7 weeks)
- Offer the same dosing regimen (12 mg intramuscularly every 24 hours for 2 doses) only to women meeting high-risk criteria: singleton pregnancy with high probability of delivery within 7 days and before 37 weeks. 4, 5
- High-risk criteria include preterm labor with cervical dilation ≥3 cm or ≥75% effacement, spontaneous rupture of membranes, or expected preterm delivery for medical indications like preeclampsia. 5, 1
Critical Contraindications
Do not administer dexamethasone to pregnant patients with pregestational diabetes mellitus—this significantly increases the risk of severe neonatal hypoglycemia. 4, 1, 3
- Avoid use in patients with low likelihood of delivery before 37 weeks, as this exposes infants to unnecessary risks without benefit. 4, 1
- Do not give repeat or "rescue" courses—a single course is recommended. 3
Special Populations
- Twin pregnancies <34 weeks: Administer the standard regimen. 1
- Twin pregnancies in late preterm period: Evidence is insufficient; consider on a case-by-case basis with shared decision-making. 5
- Multiple gestations reduced to singleton ≥14 weeks: Consider administration with shared decision-making. 4, 1
- Expected delivery in <12 hours: Still consider administration, as some benefit may occur. 4, 5
Important Clinical Considerations
- Do not delay medically indicated delivery to complete the steroid course in the late preterm period. 5, 1
- Neonatal hypoglycemia monitoring is necessary after administration, though 93% of cases are mild and resolve within 24 hours. 5, 3
- Thorough counseling is mandatory—patients must understand that long-term neurodevelopmental risks remain uncertain despite established short-term respiratory benefits. 4, 1
Common Pitfalls to Avoid
- Never use oral dexamethasone—the intramuscular route is non-negotiable due to significantly worse neonatal outcomes with oral administration. 2
- Avoid overuse in low-risk patients who are unlikely to deliver before 37 weeks. 1
- Do not use in diabetic patients due to contraindication related to severe neonatal hypoglycemia risk. 1, 3
- Avoid routine repeat courses, as evidence does not support this practice. 3
Evidence Note on Lower Doses
Recent research suggests that 5 mg dexamethasone may be noninferior to 6 mg for preventing respiratory distress syndrome in late preterm births (32-36 weeks), with respiratory distress syndrome rates of 2.2% vs 1.6% respectively. 6 However, current guidelines have not yet incorporated this lower dosing, and the standard 12 mg dose remains the recommended regimen based on decades of evidence and guideline consensus. 4, 5, 1, 3