This article is for informational purposes only and does not constitute medical advice. Always consult your obstetrician or neonatologist for guidance specific to your situation.

By Dr. Uzma Jabeen | MBBS, FCPS Pediatric Medicine | Consultant Pediatrician Last Reviewed: May 2026 | Child Health Club

If your doctor has told you that your baby may arrive between 34 and 37 weeks — earlier than planned — you are probably flooded with questions. One of the most common things parents ask me is: “Will my baby be able to breathe on their own?”

It is a deeply natural fear. And it leads directly to one of the most important questions in modern neonatology: should mothers receive a steroid injection before a late preterm birth to help their baby’s lungs mature faster?

This article breaks down what the latest research says — in plain language — so you can have an informed conversation with your medical team.

What Is a Late Preterm Baby?

A baby born between 34 weeks and 0 days and 36 weeks and 6 days of pregnancy is called a late preterm infant. This is different from extremely premature babies born before 28 weeks — late preterm babies often look almost like full-term newborns and may even go home within days.

But looks can be deceiving.

Late preterm babies have structurally and functionally immature lungs. Their lungs have less surface area, reduced ability to absorb fluid at birth, and lower levels of surfactant — the substance that keeps the tiny air sacs open. This is why breathing difficulties are the most common complication in this group.

Late preterm births now account for three-quarters of all preterm deliveries worldwide, making this one of the most pressing issues in maternal and child health today.

What Are Antenatal Corticosteroids (ACS)?

Antenatal corticosteroids — most commonly betamethasone injections — are given to the mother before preterm delivery. They cross the placenta and stimulate the baby’s lungs to mature faster, boosting surfactant production and preparing the airways for breathing outside the womb.

For babies born before 34 weeks, ACS are a well-established, life-saving intervention. Decades of research show they dramatically reduce:

Respiratory distress syndrome (RDS)
Newborn deaths
Brain bleeds and other serious complications

But what about babies born after 34 weeks? This has been a much more contested question — until recently.

What Does the Latest Research Show?

A 2020 prospective study published in The Journal of Maternal-Fetal & Neonatal Medicine by Üstün and colleagues examined exactly this question in a real-world clinical setting.

About the Study

595 mothers at risk of delivering between 34 and 36+6 weeks were enrolled over 3 years at a tertiary hospital in Istanbul, Turkey
234 mothers received two doses of betamethasone (12 mg, 24 hours apart)
361 mothers did not receive steroids
Researchers tracked what happened to the babies in the first 72 hours of life and beyond

The Good News: Breathing Improved Significantly

After accounting for differences between the two groups, the steroid-treated babies showed meaningful improvements:

Overall need for breathing support in the first 72 hours was significantly reduced (adjusted odds ratio 0.63)
CPAP or high-flow nasal cannula use dropped significantly (aOR 0.57)
Transient tachypnea of the newborn (TTN) — a common “wet lung” condition in late preterm babies — was nearly halved (aOR 0.48)

In plain terms: babies whose mothers received steroids were considerably less likely to need a breathing machine or oxygen support in those critical first days of life.

The Important Warning: Blood Sugar Risk Rises

No medical treatment is without trade-offs. Babies in the steroid group had a significantly higher rate of low blood sugar (hypoglycemia) — 20.9% versus 13% in the control group (aOR 1.64).

Neonatal hypoglycemia is not trivial. Persistent low blood sugar in newborns has been linked to poorer neurological outcomes, and it requires close monitoring, early feeding, and sometimes glucose supplementation in the neonatal unit.

What Did Not Change?

Several outcomes showed no significant difference between the two groups:

Rates of respiratory distress syndrome (RDS)
Need for surfactant therapy
Need for resuscitation at birth
Jaundice requiring phototherapy
NICU admission rates
Length of hospital stay (around 6 days in both groups)

How Does This Fit With Other Research?

This study is consistent with the landmark ALPS trial (Gyamfi-Bannerman et al., 2016) — the largest study ever done on ACS in late preterm pregnancies, involving thousands of women. The ALPS trial found the same two things: reduced respiratory support needs, and increased hypoglycemia.

A subsequent meta-analysis of three major trials covering over 3,200 women confirmed these findings, showing lower rates of severe RDS and TTN with steroids, alongside higher hypoglycemia rates.

Based on this body of evidence, the Society of Maternal-Fetal Medicine (SMFM) recommends ACS for women at risk of late preterm delivery who have not previously received a course.

What Are the Risks of Antenatal Steroids?

While the respiratory benefits are real, parents and clinicians should be aware of the following concerns:

Neonatal hypoglycemia — the most consistently reported side effect, requiring neonatal blood sugar monitoring
Long-term effects — research is ongoing into whether ACS exposure in the late preterm period affects brain development, as this is an active phase of neurological growth
Incomplete dosing — in real clinical settings, many mothers deliver before the full two-dose course is complete, which may limit effectiveness

Should You Ask for Steroids Before Late Preterm Delivery?

This is a conversation to have with your obstetric team — not a decision to make alone. The right answer depends on:

Your exact gestational age at risk of delivery
The reason for early delivery (spontaneous labour, PPROM, pre-eclampsia, etc.)
Whether you have previously received a course of ACS
Your baby’s individual risk profile

What the evidence tells us is that for most women facing imminent late preterm delivery, the respiratory benefits of ACS outweigh the hypoglycemia risk — provided the baby is carefully monitored after birth.

Frequently Asked Questions

What weeks are considered “late preterm”?

Late preterm is defined as delivery between 34 weeks 0 days and 36 weeks 6 days of pregnancy.

How are antenatal steroids given?

The standard regimen is two injections of betamethasone (12 mg each), given into the muscle 24 hours apart, before delivery.

How quickly do steroids work for the baby’s lungs?

The maximum benefit is typically seen 24–48 hours after the first dose. Some benefit may still occur even if delivery happens before the second dose.

Can antenatal steroids cause harm to my baby?

The most well-documented risk is neonatal hypoglycemia (low blood sugar). Neonatal teams routinely monitor blood sugar after birth in steroid-exposed babies. Long-term effects on brain development are still being studied.

Will my baby definitely need NICU if born at 35 weeks?

Not necessarily. Many late preterm babies do well in a special care nursery or even with the mother, depending on their clinical condition. Steroid exposure before birth may reduce the likelihood of needing intensive respiratory support.

Does the research apply to all late preterm deliveries?

This study excluded mothers with diabetes, prior steroid exposure, major fetal anomalies, and chorioamnionitis. Always discuss your specific situation with your doctor.

The Bottom Line

Late preterm birth sits in a complicated middle ground — these babies are often underestimated in their vulnerability. The evidence now clearly shows that a short course of antenatal steroids before late preterm delivery can meaningfully reduce breathing difficulties in the first days of life.

But the blood sugar risk is real, and long-term neurodevelopmental questions remain open. The goal is not to fear this intervention — it is to use it wisely, with proper neonatal monitoring in place.

If you or someone you love is facing the possibility of a late preterm birth, speak openly with your medical team about whether ACS is right for your situation.

Reference

Üstün N, Hocaoğlu M, Turgut A, Arslanoğlu S, Ovalı F. Does antenatal corticosteroid therapy improve neonatal outcomes in late preterm birth? The Journal of Maternal-Fetal & Neonatal Medicine. Published online 28 August 2020. DOI: 10.1080/14767058.2020.1808614

About the Author

Dr. Uzma Jabeen is a Consultant Pediatrician with MBBS and FCPS in Pediatric Medicine. With extensive clinical experience in neonatal and child health, she founded Child Health Club to bridge the gap between complex medical research and everyday parenting. Her mission is simple: every child deserves care backed by evidence, and every parent deserves to understand it. She writes regularly on neonatal outcomes, childhood illness, and evidence-based parenting.

Steroid Injections Before Late Preterm Birth — Do They Really Help Your Baby Breathe?