Is dexamethasone (corticosteroid) safe to use during pregnancy?

Safety of Dexamethasone in Pregnancy

Dexamethasone use in pregnancy carries context-dependent risks and should generally be avoided for maternal indications, but is acceptable for specific fetal indications (lung maturation in preterm birth) or in very limited circumstances (fetal heart block), with the understanding that fluorinated corticosteroids like dexamethasone readily cross the placenta and pose risks of fetal harm that non-fluorinated alternatives do not. 1

Critical Distinction: Fluorinated vs. Non-Fluorinated Corticosteroids

The key safety consideration is that dexamethasone (a fluorinated corticosteroid) crosses the placenta extensively, while prednisone and prednisolone (non-fluorinated) are largely metabolized before reaching the fetus. 1

• When maternal treatment is the goal, non-fluorinated corticosteroids (prednisone, prednisolone) are strongly preferred over dexamethasone or betamethasone 1, 2
• Fluorinated corticosteroids should be reserved specifically for situations requiring direct fetal treatment 1

Approved Fetal Indications for Dexamethasone

1. Fetal Lung Maturation in Preterm Birth

• Dexamethasone is acceptable for inducing fetal lung maturity in the context of anticipated preterm birth 1
• Effective at reducing neonatal respiratory distress syndrome and mortality 3, 4
• Optimal gestational window: 31-34 weeks 4
• However, repeated doses should be avoided due to associations with neurocognitive and neurosensory disorders in offspring during childhood 1

2. Fetal First- or Second-Degree Heart Block

• In pregnant women with anti-Ro/SSA and/or anti-La/SSB antibodies and fetal first- or second-degree heart block, dexamethasone 4 mg daily orally is conditionally recommended 1
• Treatment should be limited to several weeks due to risk of irreversible fetal and maternal toxicity 1
• Dexamethasone is conditionally recommended AGAINST if complete (third-degree) heart block is present, as recent analyses do not support its use and efficacy is controversial 1

Maternal Safety Concerns

Documented Risks

• Risk of exposing both fetus and mother to long-term side effects when used for maternal indications 1
• Potential for irreversible fetal and maternal toxicity with prolonged use 1
• Adverse effects on fetal programming including risks of osteoarthritis, hypertension, fatty liver, glomerulosclerosis, depression, diabetes, and infertility in offspring 5
• Prolonged adrenal suppression in newborns 3
• Increased risks of neurodevelopmental and neuropsychological impairments 3
• Premature rupture of membranes and low birthweight babies may occur 2

FDA Labeling Warnings

• Adequate human reproduction studies have not been done with corticosteroids 6
• Use requires weighing anticipated benefits against possible hazards to mother and fetus 6
• Infants born to mothers receiving substantial doses should be carefully observed for signs of hypoadrenalism 6
• Corticosteroids appear in breast milk and could suppress growth or interfere with endogenous corticosteroid production 6
• Mothers taking pharmacologic doses should be advised not to nurse 6

Clinical Algorithm for Corticosteroid Selection in Pregnancy

For Maternal Disease Control

1. Use prednisone or prednisolone (non-fluorinated) as first-line 1, 2
2. Avoid dexamethasone and betamethasone for maternal indications 1
3. If anti-emetics with steroids are needed, use methylprednisolone or prednisolone, NOT dexamethasone or betamethasone 7

For Fetal Indications

1. Preterm birth (32-37 weeks): Dexamethasone acceptable for lung maturation, single course only 1, 3, 4
2. Fetal 1st/2nd degree heart block with anti-Ro/SSA or anti-La/SSB antibodies: Dexamethasone 4 mg daily, limited duration 1
3. Complete heart block: Do NOT use dexamethasone 1

Breastfeeding Considerations

• No specific data available on dexamethasone transfer into human milk 1
• Other corticosteroids have been used extensively during breastfeeding with no evidence of adverse effects 1
• However, FDA labeling advises against nursing when taking pharmacologic doses 6

Common Pitfalls to Avoid

• Do not use dexamethasone when prednisone/prednisolone would suffice for maternal treatment - the placental crossing difference is clinically significant 1
• Do not give repeated courses of dexamethasone for fetal lung maturation - single course only due to neurodevelopmental risks 1
• Do not continue dexamethasone beyond several weeks for fetal heart block - toxicity risks outweigh benefits 1
• Do not use dexamethasone for complete (third-degree) heart block - evidence does not support efficacy 1