Is dexamethasone (corticosteroid) safe to use during pregnancy?

Dexamethasone Safety in Pregnancy

Dexamethasone is acceptable for specific fetal indications (lung maturation before preterm delivery and fetal heart block), but should be avoided for maternal disease control due to extensive placental transfer and risk of fetal harm—use prednisone or prednisolone instead for maternal indications. 1

Critical Safety Distinction: Fluorinated vs. Non-Fluorinated Corticosteroids

The fundamental safety issue is placental transfer:

• Dexamethasone (fluorinated) crosses the placenta extensively, exposing the fetus to full maternal doses 1
• Prednisone and prednisolone (non-fluorinated) are largely metabolized by placental enzymes before reaching the fetus, making them substantially safer for maternal treatment 1
• This pharmacologic difference drives all clinical decision-making about corticosteroid selection in pregnancy 1

Approved Fetal Indications for Dexamethasone

Dexamethasone is appropriate when fetal exposure is the therapeutic goal:

Fetal Lung Maturation

• High-dose dexamethasone or betamethasone should be given per national guidance to improve fetal lung maturity if delivery is anticipated before 35 weeks' gestation 2
• Standard dosing: betamethasone 12 mg intramuscularly as two doses 24 hours apart for pregnancies at 24 0/7 to 34 6/7 weeks at risk of preterm delivery 3
• For late preterm (34 0/7 to 36 6/7 weeks): betamethasone 12 mg intramuscularly every 24 hours for 2 doses reduces respiratory support needs (RR 0.80) and severe respiratory morbidity (RR 0.67) 3
• Maximum benefit occurs when delivery happens 24 hours to 7 days after administration 3

Fetal Heart Block

• Dexamethasone 4 mg daily orally is conditionally recommended for pregnant women with anti-Ro/SSA and/or anti-La/SSB antibodies and fetal first- or second-degree heart block 1
• Do not use for complete (third-degree) heart block 1
• Do not continue beyond several weeks 1

Antiemetic Use

• Dexamethasone can be used as part of prechemotherapy antiemetic regimens during second and third trimesters 2

Maternal Indications: Avoid Dexamethasone

For maternal disease control, prednisone or prednisolone are first-line; avoid dexamethasone and betamethasone 1:

• 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
• Non-fluorinated corticosteroids are strongly preferred over dexamethasone or betamethasone for maternal treatment 1

Critical Contraindications

Do not administer antenatal corticosteroids in patients with pregestational diabetes mellitus, as it significantly increases the risk of severe neonatal hypoglycemia 3

FDA Labeling Warnings

The FDA label states that adequate human reproduction studies have not been done with corticosteroids, requiring that possible benefits be weighed against potential hazards to mother and fetus 4:

• Infants born of mothers who received substantial doses should be carefully observed for signs of hypoadrenalism 4
• Use in pregnancy requires careful risk-benefit assessment 4

Potential Long-Term Fetal Effects

Animal and preliminary human research suggests prenatal dexamethasone exposure may lead to adverse consequences through intrauterine programming 5:

• Potential sequelae include osteoarthritis, hypertension, fatty liver, glomerulosclerosis, depression, diabetes, and infertility 5
• Evidence in humans is preliminary and limited by small sample sizes 5
• These concerns reinforce the importance of restricting dexamethasone to appropriate fetal indications only 5

Common Pitfalls to Avoid

• Do not use dexamethasone when prednisone/prednisolone would suffice for maternal treatment 1
• Do not give repeated courses of dexamethasone for fetal lung maturation—single course only 1, 6
• Do not delay medically indicated delivery to complete the steroid course in the late preterm period 3
• Do not continue dexamethasone beyond several weeks for fetal heart block 1
• Do not administer after week 35 of pregnancy or within 3 weeks of planned delivery when used for chemotherapy antiemesis, to avoid hematologic complications 2

Neonatal Monitoring Requirements

• Neonatal hypoglycemia monitoring is essential, particularly in diabetic mothers (though corticosteroids are contraindicated in pregestational diabetes) 3
• Observe infants for signs of hypoadrenalism after maternal exposure to substantial corticosteroid doses 4

Breastfeeding

• 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
• Very little corticosteroid ingested by the mother enters breast milk 7