What is the recommended dose of dexamethasone for premature labor?

Dexamethasone Dose for Premature Labor

For pregnancies at risk of preterm delivery between 24 0/7 and 34 6/7 weeks gestation, administer betamethasone 12 mg intramuscularly as two doses given 24 hours apart, NOT dexamethasone, as betamethasone is the preferred agent with the strongest evidence base. 1, 2

Standard Dosing Protocol for Antenatal Corticosteroids

Betamethasone is the preferred corticosteroid for fetal lung maturation in threatened preterm labor, with the following dosing regimen 1, 2:

• 12 mg intramuscularly every 24 hours for 2 doses (total 24 mg over 48 hours) 1, 2
• Indicated for gestational ages 24 0/7 to 34 6/7 weeks at risk of preterm delivery 2
• Maximum benefit occurs when delivery happens 24 hours to 7 days after administration 2

Alternative: Dexamethasone Dosing (If Betamethasone Unavailable)

If dexamethasone must be used instead of betamethasone 3, 4:

• 24 mg total dose administered as either:
  • 6 mg intramuscularly every 12 hours for 4 doses, OR
  • 12 mg intramuscularly every 24 hours for 2 doses 3, 4

Recent evidence suggests 5-6 mg dexamethasone every 12 hours for 4 doses may be noninferior to higher doses for late preterm births (32-36 weeks), though this requires further validation 5

Late Preterm Period (34 0/7 to 36 6/7 Weeks)

For singleton pregnancies at high risk of delivery within 7 days between 34 0/7 and 36 6/7 weeks, offer betamethasone 12 mg intramuscularly every 24 hours for 2 doses 6, 1, 2. This recommendation is based on the landmark ALPS trial and carries a GRADE 1A recommendation 6.

Clinical Benefits in Late Preterm Period

• Decreased need for respiratory support: 11.6% vs 14.4% (RR 0.80) 1, 2
• Decreased severe respiratory morbidity: 8.1% vs 12.1% (RR 0.67) 1, 2
• Reduced rates of death, respiratory distress syndrome, intraventricular hemorrhage, and sepsis 1, 2

Critical Contraindications

Do NOT administer antenatal corticosteroids in the following situations:

• Pregestational diabetes mellitus: Significantly increases risk of severe neonatal hypoglycemia 6, 1, 2
• Low likelihood of delivery before 37 weeks: Avoid unnecessary fetal exposure 6, 1, 2
• Prior course already administered in the late preterm period: Single course only 1

Special Populations Requiring Clinical Judgment

Consider betamethasone administration (with shared decision-making) for 6, 1:

• Multiple gestations reduced to singleton on or after 14 0/7 weeks gestation
• Fetal anomalies
• Expected delivery in <12 hours (though evidence is limited)

Common Pitfalls to Avoid

Timing Issues

• Do not delay medically indicated delivery to complete the steroid course in the late preterm period 1
• Optimal benefit requires delivery 24 hours to 7 days after administration 2
• If delivery anticipated in <12 hours, still consider administration despite limited evidence 1

Repeat Dosing Errors

• A single course is recommended; routine repeat or "rescue" courses are NOT advised for standard preterm labor 2, 7
• Repeat courses may increase risk of cerebral palsy (2.9% vs 0.5% with single course) and decrease fetal growth parameters 7

Monitoring Requirements

Neonatal hypoglycemia monitoring is essential 1, 2:

• More common with betamethasone administration
• Typically mild and self-limited (93% resolve within 24 hours) 1, 2
• Particularly important in diabetic mothers (though corticosteroids are contraindicated in pregestational diabetes) 6

Patient Counseling

Thoroughly counsel patients that long-term neurodevelopmental effects of antenatal corticosteroids remain uncertain, though current evidence shows substantial short-term benefits outweigh known risks 6, 1, 2.