Corticosteroids During Pregnancy

Corticosteroids in pregnancy serve three purposes: foetal lung maturation before preterm birth, treatment of maternal disease (asthma, inflammatory bowel disease, lupus, adrenal insufficiency, immune thrombocytopenia, hyperemesis) and replacement therapy. Choice depends on whether the drug must cross the placenta.

Placental handling. The placenta inactivates about 90% of prednisolone and hydrocortisone, so foetal exposure is low: use these for maternal disease. Betamethasone and dexamethasone cross intact and act on the foetus: use these for lung maturation.

Maternal risks. Hyperglycaemia and gestational diabetes, hypertension, weight gain, infection, mood change, osteoporosis, premature rupture of membranes.

Foetal and neonatal risks. A small rise in oral clefts with first trimester exposure (about 1 to 2 extra in 1000), reduced birth weight with prolonged high doses, neonatal adrenal suppression (rare).

Foetal lung maturation (24 to 34 weeks and 6 days when birth is expected within 7 days).

• Betamethasone 12 mg IM, 2 doses 24 hours apart.
• Alternative: dexamethasone 6 mg IM every 12 hours for 4 doses.
• Consider from 22 weeks after senior discussion; consider at 34 to 36 weeks in selected cases except in pre-existing diabetes.
• One repeat course only if the first was over 7 to 14 days earlier, gestation is under 34 weeks and birth is again expected within 7 days.

Maternal disease. Prednisolone 5 to 60 mg orally daily depending on the disease (for example 40 to 60 mg daily for flares, tapering to the lowest dose that controls disease, ideally under 10 mg daily). Hydrocortisone 100 mg IV every 6 to 8 hours for severe flares.

Adrenal insufficiency replacement. Hydrocortisone 15 to 25 mg daily in 2 to 3 doses (for example 10 mg, 5 mg, 5 mg), with fludrocortisone 50 to 200 micrograms daily; raise hydrocortisone by 20 to 40% in the third trimester.

Intercurrent illness (stress dosing). Double or triple the oral dose for fever; hydrocortisone 100 mg IM or IV for vomiting, then 200 mg over 24 hours.

Labour and caesarean birth. For anyone on prednisolone 5 mg or more daily (or equivalent) for over 2 weeks in the last 3 months, give hydrocortisone 100 mg IV at labour onset or before caesarean section, then 50 mg IV every 6 hours (or 200 mg infusion over 24 hours) until oral intake is normal, then return to the maintenance dose.

Immune thrombocytopenia. Prednisolone 0.5 to 1 mg/kg orally daily (maximum 60 mg) for platelets under 30 x 10^9/L or bleeding; consider immunoglobulin 1 g/kg IV as an alternative.

Hyperemesis, refractory. Prednisolone 40 to 50 mg orally daily (or hydrocortisone 100 mg IV twice daily), tapered over 2 weeks to the lowest effective dose, started after 10 weeks.

Bone and glucose protection. Calcium 1 g daily and vitamin D 800 to 1000 units daily with long-term treatment. Screen for gestational diabetes at 24 to 28 weeks, and earlier (at booking and at 16 to 18 weeks) on prolonged courses.

Antenatal course adverse effects. Transient maternal hyperglycaemia for 3 to 5 days (insulin adjustment in diabetes), leucocytosis (do not mistake for infection), transient reduced foetal movements and heart rate variability for 2 to 3 days.

Infection. Chorioamnionitis, tuberculosis and fungal infection risk rises; screen for latent tuberculosis before prolonged high-dose use, and consider co-trimoxazole prophylaxis against pneumocystis pneumonia if prednisolone 20 mg or more daily is expected for over 4 weeks.

Interactions. Rifampicin, carbamazepine, phenytoin and phenobarbital halve corticosteroid levels. NSAIDs raise gastric bleeding risk. Diuretics and amphotericin add hypokalaemia. Live vaccines are contraindicated on high doses.

Special groups.

• Diabetes: raise insulin by 20 to 40% for 3 to 5 days after antenatal betamethasone, with capillary glucose 4 times daily.
• Kidney impairment: no adjustment; monitor fluid retention.
• Liver impairment: prefer prednisolone because it requires conversion; reduce dose.
• Breastfeeding: prednisolone and prednisone up to 40 mg daily are compatible; delay feeding for 4 hours after doses over 40 mg.
• Regional: HIV and tuberculosis are common; screen before prolonged courses.

Monitoring. Blood pressure, weight and glucose at each visit on prolonged therapy. Foetal growth scans every 4 weeks from 28 weeks for doses over 20 mg daily for over 4 weeks. Neonatal glucose and, after high dose prolonged exposure, adrenal function in the newborn.

Adjustment. Reduce prednisolone by 5 mg each 1 to 2 weeks to 20 mg, then by 2.5 mg each 2 weeks, to the lowest effective dose; never stop abruptly after more than 3 weeks.

Stopping rules. Do not stop replacement therapy in pregnancy. Do not repeat antenatal steroid courses beyond one rescue course.

Referral and escalation. Refer adrenal insufficiency, congenital adrenal hyperplasia (including any prenatal dexamethasone use, a specialist-only indication), prolonged high-dose therapy and steroid-induced diabetes to endocrinology and obstetric medicine.