A Steroid Shot Before Birth: Who It Really Helps When Babies Come a Few Weeks Early

What a 2025 study of 452 pregnancies tells families about steroids, cesarean birth, and breathing problems in "late preterm" babies

Babies born just a few weeks early — between 34 and 37 weeks of pregnancy, a group doctors call "late preterm" — usually look healthy and full-sized, but their lungs can still be immature enough to cause breathing trouble in the first hours of life. A 2025 study from a women's hospital in Ankara, Turkey, looked at 452 such pregnancies and asked a practical question: does a steroid injection given to the mother before birth actually protect these babies' lungs? The answer turned out to be yes — but mainly for the babies at highest risk, especially those delivered by cesarean section and those born at the earlier end of that window.

Why this question matters to families

When a baby arrives early, the most common early worry is breathing. A late preterm baby may breathe fast, grunt, or need extra oxygen or a machine called CPAP that gently pushes air into the lungs to keep them open. For most of these babies the problem is temporary, but it can mean a stay in the neonatal intensive care unit (NICU), separation from parents, and anxious days. The study by Kurt and colleagues [1] was designed to help doctors and parents understand when a simple, inexpensive treatment given before birth is genuinely worth it. Late preterm babies make up the large majority of all early births and are more fragile than their size suggests, with breathing trouble their most frequent reason for needing NICU care [2], so even a small improvement per baby adds up to a lot of families affected.

The problem families and doctors used to face

The idea of giving steroids before an early birth is not new. More than fifty years ago, two doctors named Liggins and Howie discovered that a steroid given to the mother could speed up the maturing of the baby's lungs and reduce breathing problems in premature infants [3]. For decades, though, this treatment was offered only to mothers likely to deliver quite early — before 34 weeks — because that is where the benefit was clearest. Babies born in the 34-to-37-week window were thought to be close enough to full term that steroids would not help much, so many did not receive them, and doctors simply watched and hoped when these babies had trouble breathing.

That thinking changed after a large study called the Antenatal Late Preterm Steroids (ALPS) trial [4], run across 17 university hospitals in the United States. It enrolled 2,831 pregnant women and found that a single steroid course did reduce serious breathing problems in late preterm babies — dropping the rate of severe complications from about 14 in 100 to about 12 in 100. On the strength of that study, major medical groups in the United States began recommending the steroid for at-risk pregnancies in this window [5]. But the story was not tidy: other carefully done studies, including one from Brazil [6] and a more recent one [7], found no clear benefit. Families and doctors were left with genuinely mixed evidence — which is exactly the confusion this new study set out to clear up.

What the researchers did

The team reviewed the records of 452 single-baby pregnancies delivered between 2014 and 2021, all in the 34-to-37-week window. In 197 of them the mother had received a full course of the steroid betamethasone (two injections given a day apart); in the other 255, she had not. The researchers then compared how often the babies had lung problems — defined as needing treatment for respiratory distress, needing CPAP for at least six hours, or needing a breathing machine for more than a day. Because this was a look back at existing records rather than a planned experiment, the researchers used statistical methods to fairly account for differences between the two groups of mothers.

That fairness step turned out to be the whole point. When they simply compared the two groups side by side, the steroid did not seem to make a clear difference: about 17 in 100 steroid-exposed babies had breathing problems versus 20 in 100 of the others — a gap small enough to be chance. But there was a catch hiding in the numbers. The mothers who got the steroid had, on average, delivered a little earlier and had more pregnancy complications — in other words, their babies were already at higher risk. That head start in risk made the steroid look weaker than it really was.

What they found once the numbers were fair

When the researchers adjusted for those differences, the steroid's protective effect appeared clearly: it lowered the odds of a serious breathing problem by about 42% [1]. Two other findings were just as important for families to understand. First, every extra week the baby stayed in the womb cut the risk of breathing trouble substantially — a powerful reminder that, when it is safe, a little more time inside helps a lot. Second, being born by cesarean section raised the odds of breathing problems almost fourfold compared with vaginal birth. Babies born vaginally often get a helpful "squeeze" through the birth canal that clears fluid from their lungs; babies born by cesarean miss that, which is part of why they more often struggle at first.

Putting these pieces together produced the study's most useful picture. The babies at highest risk were those delivered by cesarean at around 34 weeks without steroids — roughly 41 in 100 had a breathing problem. Giving those same babies steroids brought the risk down to about 29 in 100. At the other end, the safest situation was a vaginal birth at 36 weeks with steroids, where only about 2 in 100 babies had trouble. In short, the steroid helped most exactly where the danger was greatest, and mattered far less where the risk was already low. This fits with an analysis showing that the payoff from steroids depends heavily on a baby's gestational age and how they are born [8], and with a large review of earlier trials that also found a benefit near term [9].

What this means for you and your baby

If you are facing a possible late preterm birth, the practical takeaway is that this decision is not one-size-fits-all, and that is good news. For a mother heading toward an early cesarean, or a delivery closer to 34 weeks, a steroid course before birth offers a real, worthwhile reduction in the chance her baby will need breathing help — and it is reasonable to ask the care team about it. For a birth expected to happen vaginally and closer to 37 weeks, the baby's starting risk is already low, so the added benefit is small, and doctors may reasonably hold off. None of this is a decision to make alone; it is a conversation to have with your obstetric team using your own specific situation — how many weeks along you are and how you are likely to deliver.

It is also fair to know the other side. Steroids given this late in pregnancy can make a baby's blood sugar drop temporarily, so steroid-exposed babies are watched closely for low glucose; in this study, low blood sugar was equally common in both groups [1]. Doctors also continue to study whether late steroids have any longer-term effects as children grow [10], [11]. That is why medical groups recommend giving these steroids thoughtfully rather than to everyone. And there is an empowering flip side to the cesarean finding: because cesarean birth itself raises the risk of breathing problems, avoiding a cesarean that is not medically needed, and safely letting a pregnancy continue a bit longer, can protect a baby's lungs just as much as any medicine.

What researchers are working on next

This study looked back at records from a single hospital, which is a real limitation — it cannot prove cause and effect the way a planned experiment can, and its findings need confirmation elsewhere. Researchers now want to run larger studies across many hospitals, compare different steroid types and doses, and — most importantly — follow these children for years to make sure that easing early breathing problems does not carry any hidden long-term cost [11]. For now, the message families can take from this work is reassuring and clear: a well-timed steroid, given to the right pregnancies, is a small step that can spare a vulnerable newborn a hard first few days — and the "right pregnancies" are ones your care team can identify with you [12].

References

  1. Kurt A, Ulusoy CO, Sarikaya Kurt D, Özkan S, Dereli ML, Kından A, Yücel Çelik Ö, Uzlu SE, Çelen Ş. Impact of antenatal corticosteroid therapy on neonatal respiratory outcomes in late preterm births. BMC Pediatrics. 2025;25:595. doi:10.1186/s12887-025-05925-w ↩
  2. Raju TNK, Higgins RD, Stark AR, Leveno KJ. Optimizing care and outcome for late-preterm (near-term) infants: a summary of the workshop sponsored by the National Institute of Child Health and Human Development. Pediatrics. 2006;118(3):1207–1214. doi:10.1542/peds.2006-0018 ↩
  3. Liggins GC, Howie RN. A controlled trial of antepartum glucocorticoid treatment for prevention of the respiratory distress syndrome in premature infants. Pediatrics. 1972;50(4):515–525. PubMed 4561295 ↩
  4. Gyamfi-Bannerman C, Thom EA, Blackwell SC, Tita ATN, Reddy UM, Saade GR, et al. Antenatal betamethasone for women at risk for late preterm delivery. N Engl J Med. 2016;374(14):1311–1320. doi:10.1056/NEJMoa1516783 ↩
  5. Committee on Obstetric Practice. Committee Opinion 713: Antenatal corticosteroid therapy for fetal maturation. Obstet Gynecol. 2017;130(2):e102–e109. doi:10.1097/AOG.0000000000002237 ↩
  6. Porto AMF, Coutinho IC, Correia JB, Amorim MMR. Effectiveness of antenatal corticosteroids in reducing respiratory disorders in late preterm infants: randomised clinical trial. BMJ. 2011;342:d1696. doi:10.1136/bmj.d1696 ↩
  7. Yenuberi H, Ross B, Sasmita Tirkey R, Benjamin SJ, Rathore S, Karuppusami R, et al. Late-preterm antenatal steroids for reduction of neonatal respiratory complications: a randomized controlled trial. Obstet Gynecol. 2024;143(4):468–474. doi:10.1097/AOG.0000000000005520 ↩
  8. Clapp MA, Li S, Cohen JL, Gyamfi-Bannerman C, Knudsen AB, Lorch SA, et al. Betamethasone exposure and neonatal respiratory morbidity among late preterm births by planned mode of delivery and gestational age. Obstet Gynecol. 2024;144(6):747–754. doi:10.1097/AOG.0000000000005756 ↩
  9. Saccone G, Berghella V. Antenatal corticosteroids for maturity of term or near term fetuses: systematic review and meta-analysis of randomized controlled trials. BMJ. 2016;355:i5044. doi:10.1136/bmj.i5044 ↩
  10. Kamath-Rayne BD, Rozance PJ, Goldenberg RL, Jobe AH. Antenatal corticosteroids beyond 34 weeks gestation: what do we do now? Am J Obstet Gynecol. 2016;215(4):423–430. doi:10.1016/j.ajog.2016.06.023 ↩
  11. Jobe AH, Goldenberg RL. Antenatal corticosteroids: an assessment of anticipated benefits and potential risks. Am J Obstet Gynecol. 2018;219(1):62–74. doi:10.1016/j.ajog.2018.04.007 ↩
  12. Society for Maternal-Fetal Medicine (SMFM) Publications Committee. Implementation of the use of antenatal corticosteroids in the late preterm birth period in women at risk for preterm delivery. Am J Obstet Gynecol. 2016;215(2):B13–B15. doi:10.1016/j.ajog.2016.03.013 ↩