What steroid is used for preterm labor?

Betamethasone is the Recommended Steroid for Preterm Labor

Betamethasone is the recommended antenatal corticosteroid for preterm labor, administered as 2 doses of 12 mg intramuscular injections 24 hours apart to patients at high risk of preterm birth within 7 days. 1, 2

Indications for Betamethasone Administration

• Betamethasone is indicated for singleton pregnancies between 34 0/7 and 36 6/7 weeks of gestation who are at high risk of preterm birth within the next 7 days 1, 2
• Specific indications include:
  • Preterm labor with intact membranes and cervical dilation of 3 cm or 75% cervical effacement 1, 2
  • Spontaneous rupture of the membranes 1, 2
  • Expected preterm delivery for other indications such as gestational hypertension, preeclampsia, or fetal growth restriction 1, 2
• A single course of corticosteroids is also recommended for pregnant women between 24 0/7 weeks and 33 6/7 weeks of gestation who are at risk of preterm delivery within 7 days 3, 4

Benefits of Betamethasone Administration

• Antenatal betamethasone administration significantly decreases:
  • Need for respiratory support (11.6% vs 14.4%; relative risk 0.80) 1, 2
  • Severe respiratory morbidity (8.1% vs 12.1%; relative risk 0.67) 1, 2
  • Neonatal mortality (odds ratio 0.60) 5
  • Intraventricular hemorrhage 5
  • Patent ductus arteriosus and necrotizing enterocolitis 6
• These benefits extend across a broad range of gestational ages and are not limited by gender or race 5

Dosing Protocol

• The standard regimen is 2 doses of 12 mg intramuscular betamethasone administered 24 hours apart 1, 2
• Betamethasone is preferred over dexamethasone, although both are effective fluorinated steroids that cross the placenta 6
• Less potent corticosteroids such as cortisol, cortisone, and prednisone are not as effective for accelerating fetal lung maturation 6

Special Populations and Considerations

• Consider betamethasone for select populations not included in the original ALPS trial:
  • Patients with multiple gestations reduced to singleton gestation on/after 14 0/7 weeks 1, 2
  • Patients with fetal anomalies 1
  • Patients expected to deliver in <12 hours 1
• Do NOT administer betamethasone to:
  • Pregnant patients with a low likelihood of delivery before 37 weeks of gestation 1
  • Pregnant patients with pregestational diabetes mellitus due to risk of worsening neonatal hypoglycemia 1, 2

Potential Risks and Monitoring

• Neonatal hypoglycemia is more common with betamethasone administration but is typically mild and self-limited (93% resolve within 24 hours) 1, 2
• When administering betamethasone, solutions should be preservative-free when used in neonates, especially premature infants, as benzyl alcohol has been associated with a fatal "Gasping Syndrome" 7
• Long-term neurodevelopmental effects remain uncertain, requiring thorough patient counseling about potential risks and benefits 1, 2

Repeat Courses

• A single repeat course of antenatal corticosteroids should be considered in 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 clinically indicated 3, 4

Common Pitfalls to Avoid

• Administering betamethasone to patients with pregestational diabetes mellitus, which can worsen neonatal hypoglycemia 1
• Using betamethasone in patients with a low likelihood of delivery before 37 weeks, exposing the fetus to unnecessary medication 1
• Failing to recognize the optimal window for administration (within 7 days of anticipated delivery) 1
• Using less potent corticosteroids (cortisol, cortisone, prednisone) which are not as effective for lung maturation 6