What is the recommended antenatal corticosteroid regimen (dose, timing, repeat courses, and contraindications) for a pregnant woman at 24–34 weeks gestation who is at risk of delivery within seven days?

Antenatal Corticosteroid Regimen for Preterm Birth Risk

For pregnant women at 24–34 weeks gestation at risk of delivery within 7 days, administer betamethasone 12 mg intramuscularly in two doses, 24 hours apart, as a single course. 1, 2

Standard Dosing Regimen

• Betamethasone 12 mg IM × 2 doses, 24 hours apart is the preferred regimen for all women between 24 0/7 and 33 6/7 weeks of gestation who are at risk of preterm delivery within 7 days. 3, 4

• Dexamethasone 12 mg IM × 2 doses, 24 hours apart is an acceptable alternative if betamethasone is unavailable. 1

• The maximum benefit occurs when delivery happens 24 hours to 7 days after administration. 5

Timing and Gestational Age Windows

Standard Window (24–34 weeks)

• A single course is strongly recommended for all pregnant women between 24 0/7 and 33 6/7 weeks of gestation at risk of delivery within 7 days, including those with ruptured membranes and multiple gestations. 3, 4

• Administration may be considered starting at 23 0/7 weeks of gestation based on family decisions regarding resuscitation, irrespective of membrane rupture status and fetal number. 3, 4

Late Preterm Window (34–36 6/7 weeks)

• Betamethasone may be considered for singleton pregnancies between 34 0/7 and 36 6/7 weeks who meet high-risk criteria for delivery within 7 days and have not received a previous course. 1, 2, 3

• High-risk criteria include: preterm labor with intact membranes and cervical dilation ≥3 cm or ≥75% cervical effacement, spontaneous rupture of membranes, or anticipated preterm birth for obstetric indications (e.g., preeclampsia, fetal growth restriction). 1, 2

• Do not delay medically indicated delivery to complete the steroid course in the late preterm period. 1, 2

Repeat and Rescue Courses

Rescue Course (Before 34 weeks)

• A single repeat course should be considered for women less than 34 0/7 weeks of gestation who remain at risk of preterm delivery within 7 days and whose prior course was administered more than 14 days previously. 3, 4

• Rescue course corticosteroids could be provided as early as 7 days from the prior dose if indicated by the clinical scenario. 3, 4

• Important caveat: Repeated doses are recognized to reduce infant birthweight and head circumference. 6

Late Preterm Period (34–36 6/7 weeks)

• Do not administer routine repeat or rescue courses for late preterm gestations (34–36 weeks). 5

• Do not administer to patients who have already received a prior course in the late preterm period. 2

Absolute Contraindications

• Pregestational diabetes mellitus is an absolute contraindication due to markedly increased risk of severe neonatal hypoglycemia. 1, 2

• Low likelihood of delivery before 37 weeks—do not administer to women unlikely to deliver preterm, as potential harms outweigh benefits. 1, 2

Special Populations

Multiple Gestations

• Twin pregnancies less than 34 weeks: Administer the standard regimen. 2

• Twin pregnancies 34–36 6/7 weeks: Evidence is insufficient; use shared decision-making on a case-by-case basis. 1, 2

• Multiple gestations reduced to singleton ≥14 0/7 weeks: Consider administration with shared decision-making. 1, 2

Hypertensive Disorders

• Corticosteroids for fetal pulmonary maturity should be considered for all women presenting with pre-eclampsia at ≤34 weeks of gestation. 6

• For women with gestational hypertension presenting at ≤34 weeks, administer only if delivery is considered within the next 7 days. 6

• A rescue dose may be considered for women at ≤34 weeks remaining at high risk of preterm delivery 14 days or more after an initial course. 6

Elective Cesarean Section

• Antenatal corticosteroids may be considered for women delivering by elective cesarean section at ≤38 weeks' gestation to reduce respiratory morbidity. 6

Clinical Benefits

• Reduces respiratory distress syndrome by 29% (RR 0.71,95% CI 0.65-0.78) and decreases need for respiratory support by 20% (RR 0.80,95% CI 0.66-0.97). 1

• Reduces severe respiratory complications by 33% (RR 0.67,95% CI 0.53-0.84). 1

• Reduces risks of neonatal death, intraventricular hemorrhage, and sepsis. 2

Potential Risks and Counseling Requirements

• Neonatal hypoglycemia occurs more frequently after betamethasone exposure, but 93% of cases are mild, self-limited, and resolve within 24 hours. 1, 2

• Thorough counseling is mandatory regarding short-term neonatal benefits and uncertain long-term neurodevelopmental risks. 1, 2

• Long-term neurodevelopmental effects remain uncertain and require ongoing surveillance. 2, 3

Common Pitfalls to Avoid

• Do not overuse in low-risk patients—this exposes infants to unnecessary risks without benefit. 1

• Do not confuse rescue steroids with late preterm steroids—these are distinct clinical scenarios with different evidence bases. 5

• Do not administer to diabetic patients—the risk of severe neonatal hypoglycemia is unacceptable. 1, 2

• Do not routinely repeat courses beyond the evidence-based rescue scenario (before 34 weeks, ≥14 days after initial course). 7, 8