What is the recommended regimen for administering dexamethasone (corticosteroid) to a pregnant woman at 35 weeks gestation?

Dexamethasone at 35 Weeks Gestation

Administer betamethasone 12 mg intramuscularly in two doses, 24 hours apart, to pregnant women at 35 weeks gestation who have a singleton pregnancy and are at high risk of delivery within the next 7 days and before 37 weeks. 1, 2

Recommended Dosing Regimen

• The preferred corticosteroid is betamethasone 12 mg intramuscularly, given as two doses separated by 24 hours. 1, 2, 3
• Dexamethasone 12 mg intramuscularly in two doses, 24 hours apart, is an acceptable alternative only if betamethasone is unavailable. 2
• This recommendation applies specifically to gestational ages between 34 0/7 and 36 6/7 weeks (the "late preterm" period). 1, 2

Who Qualifies for Treatment at 35 Weeks

You should offer corticosteroids to patients who meet all of the following criteria: 1

• Singleton pregnancy (including twin pregnancies reduced to singleton before 14 0/7 weeks)
• Gestational age between 34 0/7 and 36 6/7 weeks
• High probability of delivery within 7 days demonstrated by:
  • Preterm labor with cervical dilation ≥3 cm OR cervical effacement ≥75% 1, 2
  • Spontaneous rupture of membranes 1, 2
  • Expected preterm delivery for medical indications (preeclampsia, fetal growth restriction, oligohydramnios) with planned delivery between 24 hours and 7 days 1, 2

Clinical Benefits at 35 Weeks

• Reduces need for respiratory support by 20% (11.6% vs 14.4%; RR 0.80). 2, 3
• Reduces severe respiratory morbidity by 33% (8.1% vs 12.1%; RR 0.67). 2, 3
• These benefits are based on the landmark ALPS trial, which specifically studied this gestational age range. 1

Absolute Contraindications

Do not administer corticosteroids if: 1, 2, 3

• The patient has pregestational diabetes mellitus - this significantly increases the risk of severe neonatal hypoglycemia and is a firm contraindication. 1, 2, 3
• There is low likelihood of delivery before 37 weeks - corticosteroids should not be used for fetal lung maturity when delivery is unlikely. 1, 2

Critical Timing Considerations

• Maximum benefit occurs when delivery happens 24 hours to 7 days after administration. 3
• The corticosteroid course should be completed (both doses given) for optimal effect. 1
• Only give a single course - do not repeat or give "rescue" courses in the late preterm period. 3

Important Adverse Effects and Monitoring

• Neonatal hypoglycemia occurs more frequently with corticosteroid exposure, but 93% of cases resolve within 24 hours and are mild and self-limited. 1, 3, 4
• Neonates require blood glucose monitoring after birth, particularly in the first 24 hours. 1
• Long-term neurodevelopmental effects remain uncertain - patients must be counseled that while short-term respiratory benefits are established, long-term risks are not fully known. 1, 2

Special Populations to Consider

You may consider corticosteroid administration in select populations not included in the original ALPS trial, though evidence is weaker: 1, 2

• Multiple gestations reduced to singleton on or after 14 0/7 weeks
• Pregnancies with fetal anomalies
• Patients expected to deliver in <12 hours

Common Pitfalls to Avoid

• Do not withhold treatment based on gestational diabetes alone - only pregestational diabetes is a contraindication; gestational diabetes was included in the ALPS trial. 1
• Do not administer corticosteroids "just in case" - there must be genuine high risk of delivery within 7 days. 1
• Do not use dexamethasone as first-line - betamethasone is the preferred agent with the strongest evidence base. 1, 2, 3