ANTENATAL CORTICOSTEROIDS

SWARAJ HOSPITAL & RESEARCH INSTITUTE

BOLANGIR, ODISHA  •  OBSTETRICS & GYNAECOLOGY CLINICAL PATHWAY SERIES

Clinician Reference Infographic

Antenatal Corticosteroids (ACS) — A Practical Guide

Antenatal corticosteroids accelerate fetal lung maturation when given to a woman at risk of preterm birth, meaningfully reducing neonatal respiratory distress syndrome, intraventricular haemorrhage, and death. They are one of the highest-yield interventions in all of obstetrics — but the benefit depends heavily on giving the right drug, at the right time, in the right window before delivery.

🎯 AT A GLANCE — WHO SHOULD RECEIVE ACS

Any woman at risk of preterm birth within the next 7 days — from preterm labor, PPROM, or a planned preterm delivery for a maternal or fetal indication

GREEN — Term (≥37 weeks): not indicated

AMBER — Late preterm (34+0 to 36+6 weeks): consider if birth is likely within 7 days and no prior course has been given — benefit is real but more modest

RED — Early/moderate preterm (24+0 to 33+6 weeks): strongly indicated if birth is likely within 7 days — give promptly

💉 DRUGS & DOSING REGIMENS

Betamethasone: 12 mg IM, two doses, 24 hours apart

Dexamethasone: 6 mg IM, four doses, 12 hours apart

Either drug is acceptable — choice usually comes down to local availability and protocol, not a meaningful difference in benefit

A "complete course" means every scheduled dose has been given — but even a partial course has some benefit if delivery happens sooner than expected.

🔬 MECHANISM OF ACTION — HOW ACS WORKS

Betamethasone and dexamethasone cross the placenta and bind glucocorticoid receptors in fetal tissue, switching on genes that drive structural maturation

In the lungs: accelerates maturation of type II pneumocytes and boosts surfactant production — surfactant lowers surface tension in the air sacs, keeping them open after birth

Also thins the air–blood barrier and increases lung compliance, so the newborn lung is mechanically ready to breathe air effectively

Beyond the lungs: stabilizes fragile blood vessels in the brain's germinal matrix (lowering IVH risk) and matures the gut lining (lowering NEC risk)

Timeline of effect: measurable benefit starts around 18–24 hours after the first dose, peaks near 48 hours, and lasts about 7 days — this is exactly why the "24 hours to 7 days" window exists.

⏱️ THE OPTIMAL TIMING WINDOW

Best benefit: delivery occurring 24 hours to 7 days after completing the course

Delivered sooner: even a single dose shortly before birth offers some benefit — never withhold it because "there's no time to finish"

Delivered later: benefit fades beyond 7 days — a single rescue course may be considered if still preterm and now at renewed risk

🚨 NEVER DELAY DELIVERY FOR STEROIDS

Non-reassuring fetal status, severe pre-eclampsia with uncontrolled BP, or placental abruption all override waiting for a steroid course

Give the first dose if time genuinely allows — but the obstetric indication for urgent delivery always comes first

A partial or even a single dose is still worthwhile; an unsafe delay is not

🔁 REPEAT (RESCUE) COURSE

Consider one rescue course if the prior course was given more than 7–14 days ago (per local protocol), the pregnancy is still under 34 weeks, and preterm birth is now likely again within 7 days

Avoid multiple repeat courses — repeated exposure has been linked to lower birth weight and raises theoretical concerns about neurodevelopment

One rescue course is reasonable; routine repeated courses are not — individualize beyond a single rescue with senior input.

💧 SPECIAL SITUATION — PRETERM PRELABOUR RUPTURE OF MEMBRANES (PPROM)

PPROM is one of the most common reasons ACS is given — ruptured membranes themselves don't change the dose or drug choice

Give a course promptly on diagnosis if the pregnancy is under the usual gestational cut-off, since the time to delivery after PPROM is often unpredictable

ACS does not meaningfully increase maternal or neonatal infection rates in PPROM — this has been consistently shown across trials, and the lung benefit for the baby outweighs the theoretical infection concern

Best paired with latency antibiotics per local protocol — steroids and antibiotics are complementary decisions here, not competing ones

Watch for the interpretation trap: the transient leukocytosis steroids cause (see Side Effects) can muddy infection markers in a population already at higher infection risk. Lean on clinical signs — fever, uterine tenderness, fetal tachycardia, foul-smelling liquor — more than an isolated raised WBC in the days after dosing.

If the pregnancy continues well past the 7-day benefit window without delivery, and preterm birth risk re-emerges, a single rescue course can be considered — same criteria as above

👶 WHY WE GIVE IT — NEONATAL BENEFITS

Reduces respiratory distress syndrome (RDS) and the need for respiratory support

Reduces intraventricular haemorrhage (IVH), necrotizing enterocolitis (NEC), and neonatal death

Benefit is strongest from 24–34 weeks; in the late preterm window (34–36+6 weeks) the effect is more modest but still real — mainly less transient respiratory distress

⚠️ SIDE EFFECTS TO ANTICIPATE

Maternal

Transient hyperglycaemia — peaks 12–24 hours after a dose and can last several days; matters most in diabetic mothers

Transient leukocytosis (raised white cell count) — can mimic or mask signs of infection on blood tests

Mild, usually clinically insignificant rise in blood pressure

Rare — pulmonary oedema: risk rises when steroids are combined with tocolytics and generous IV fluids; watch fluid balance closely

Fetal / Neonatal

Transiently reduced fetal movements and heart rate variability for 48–96 hours — an expected response, not a sign of compromise

Neonatal hypoglycaemia — from rebound after the maternal glucose effect wears off

With repeated courses: lower birth weight, and theoretical neurodevelopmental concerns (see Repeat Course above)

Most of these effects are transient and expected — anticipating a temporary dip in fetal heart rate variability after dosing prevents unnecessary alarm or unnecessary intervention.

Diabetes (Pre-existing or Gestational)

Steroids transiently raise maternal blood glucose

Anticipate closer glucose monitoring, and possible insulin adjustment, for 3–5 days

Suspected Chorioamnionitis

Not an absolute contraindication

Weigh infection risk individually, with senior input

Multiple Pregnancy

Same maternal dose regardless of the number of fetuses

Indication and timing principles are unchanged

Late Preterm (34–36+6 wks)

Only if no prior course was given

Smaller absolute benefit — still worth giving if birth is likely within 7 days

Optimal Window

24 Hours to 7 Days

1hr–7d

FROM FIRST DOSE
TO BEST-TIMED DELIVERY

Maximum neonatal benefit occurs when delivery happens in this window after the course is completed — not so soon that the drug hasn't acted, and not so late that the effect has faded.

Even a single dose shortly before birth has some benefit — don't withhold it because delivery seems imminent

If delivery ends up more than 7 days away, reconsider a single rescue course closer to the time, if still preterm

Never delay a medically necessary urgent delivery solely to finish the steroid course

Document the timing of each dose clearly — it shapes what the neonatal team expects and plans for

Reminder: the goal is a baby delivered in the window of benefit, not a "completed course" for its own sake.

Swaraj Hospital & Research Institute · Department of Obstetrics & Gynaecology, Bolangir, Odisha

Clinician-facing summary for structured teaching and triage; exact gestational cut-offs, repeat-course intervals, and dosing regimens vary by guideline — follow local institutional protocol.