Preterm Birth Treatments Under Scrutiny: Rethinking Steroid Shots Between 30 and 34 Weeks

Table of Contents

• Key Points
• Why This Debate Matters
• The APOSTEL 8 Trial: What It Found
• What Are Antenatal Corticosteroids?
• The Evidence Gap After 30 Weeks
• Safety Concerns: What Do We Know So Far?
• Searching for Better Dosing Strategies
• Twin Pregnancies and Contraction-Stopping Drugs
• What the Experts Recommend
• Limitations to Keep in Mind
• What This Means for Patients
• Frequently Asked Questions
• Source Information

Key Points

• Atosiban delayed birth beyond 48 hours in 78% of women versus 69% with placebo, but newborn outcomes did not improve.
• Antenatal corticosteroids remain standard care for threatened preterm birth, but their benefit between 30 and 34 weeks is now questioned.
• Evidence cited includes observational studies of over 1.25 million children linking corticosteroids to higher rates of mental and behavioral disorders, though causation is not proven.
• Experts recommend re-evaluating corticosteroid dosing, possibly using reduced or gestational-age-tailored regimens instead of one uniform course.
• The planned 4-year follow-up of APOSTEL 8 and the ongoing SNACS trial aim to provide more answers on long-term outcomes and reduced dosing.

Why This Debate Matters

Preterm birth — birth before 37 weeks of pregnancy — is one of the biggest challenges in modern obstetrics. When a woman goes into labor early, doctors have two main tools. The first is a tocolytic drug such as atosiban, which temporarily stops or slows contractions to buy time. The second is an injection of antenatal corticosteroids (steroids given before birth), which speed up fetal lung development and reduce the risk of breathing problems after birth.

On September 27, 2025, The Lancet published a scholarly exchange about the APOSTEL 8 trial, which compared atosiban with placebo in 752 women with threatened preterm birth between 30+0 and 33+6 weeks of gestation (that is, from exactly 30 weeks through almost 34 weeks). Two groups of experts wrote letters criticizing how the results should be interpreted, and the trial authors, Larissa I van der Windt and Martijn A Oudijk of Amsterdam University Medical Center, replied. This is a conversation between specialists — not a new study — but it has direct relevance for anyone facing threatened preterm birth.

The APOSTEL 8 Trial: What It Found

The APOSTEL 8 trial randomly assigned 752 participants to receive either atosiban (a medication that blocks the hormone oxytocin and relaxes the uterus) or a placebo (an inactive saltwater infusion). The drug clearly worked at delaying birth.

• Pregnancy was prolonged beyond 48 hours in 78% of women who received atosiban, compared with 69% of women who received placebo.
• That translates to a relative risk (RR) of 1.13 (95% CI 1.03–1.23). In plain terms, women on atosiban were about 13% more likely to reach the 48-hour mark, and the confidence interval suggests the true benefit lies between a 3% and a 23% relative increase.
• More women in the atosiban group completed a full course of antenatal corticosteroids: 76% versus 68% (RR 1.11, 95% CI 1.02–1.22).

Despite this, atosiban did not improve neonatal (newborn) outcomes. The authors point out that nearly 98% of all participants received at least one dose of antenatal corticosteroids, which may explain why the extra delay made little difference to the babies. Put another way: if the steroid treatment itself is not providing much benefit at this stage of pregnancy, then winning more time to give it may not help.

What Are Antenatal Corticosteroids?

Antenatal corticosteroids are medications such as betamethasone or dexamethasone, given to a pregnant woman when preterm birth is threatened. They cross the placenta and accelerate maturation of the fetal lungs and other organs, reducing the risk of respiratory distress syndrome, bleeding in the brain, and death after early birth.

The standard regimen — which has been used for decades — consists of two doses given 24 hours apart, completed within 48 hours. The experts in this exchange note that this regimen is based on clinical trials conducted in the 1970s and 1980s. They question whether those old trials still apply to babies born between 30+0 and 33+6 weeks of gestation.

Why does that question matter? Preterm-related illness and death decline steeply between 28 weeks and 30 weeks of gestation. By 30 to 34 weeks, a baby's baseline risk of severe complications is much lower. Although antenatal corticosteroids probably contributed to the overall improvement in outcomes, the benefit–risk balance of this medication after 30 weeks is unclear.

The Evidence Gap After 30 Weeks

Robust data on whether corticosteroids work between 30+0 and 33+6 weeks remain sparse. The correspondents — Ruben Ramirez Zegarra, Beatrice Valentini, and Tullio Ghi — cite several lines of evidence suggesting that the benefit may be smaller than assumed.

• One observational study of more than 13,000 infants born between 23 and 32 weeks found no survival or respiratory benefit for infants born after 29 weeks.
• Subgroup analyses from randomized trials are inconsistent, with some showing benefits between 30 and 34 weeks and others showing no benefit.
• The APOSTEL 8 trial itself hinted that a partial course of corticosteroids could be safe after 30 weeks.

These findings raise a difficult question: is the standard full course of steroids still worth giving — and worth its potential risks — when a baby is expected to be born at 31, 32, or 33 weeks?

Safety Concerns: What Do We Know So Far?

Safety concerns about antenatal corticosteroids are not new. The correspondents emphasize that the risks appear to be dose-dependent, and repeated courses of corticosteroids have been linked to both short-term and long-term adverse outcomes.

• Animal studies have found delayed fetal brain growth and impaired development of the cerebral cortex (the brain's outer layer, responsible for higher functions).
• Human cohort studies have reported increased rates of mental and behavioral disorders in children who were born preterm and exposed to antenatal corticosteroids before birth.
• A recent meta-analysis of more than 1.25 million children found elevated risks of such disorders even in late-preterm and full-term infants who had been exposed to antenatal corticosteroids.

One meta-analysis of long-term outcomes associated with preterm exposure to corticosteroids (published in JAMA Pediatrics in 2022) and another large study in JAMA (2020) are specifically cited as evidence for these risks. The trial authors acknowledge these concerns, noting the potential for long-term adverse effects in children who are ultimately born at full term.

Searching for Better Dosing Strategies

Given the evidence gaps, the correspondents argue that modern obstetrics needs to move toward more personalized approaches. Instead of using one uniform corticosteroid regimen for every threatened preterm birth between 24+0 and 33+6 weeks, they propose reduced or gestational age-tailored dosing (doses adjusted to the exact week of pregnancy).

Some evidence supports this idea. A non-inferiority trial involving 3,244 participants tested a single 11.4 mg dose of betamethasone against the standard two-dose regimen. That trial failed to show non-inferiority, meaning the single reduced dose could not be proven to be as good as the standard course. The authors of that trial noted methodological limitations, especially in how outcomes were selected, but their results still emphasized the need for more research.

Fortunately, additional studies are underway. The ongoing SNACS trial (NCT05114096) is expected to provide new insights into whether reduced antenatal corticosteroid dosing is sufficient.

The trial authors add an important nuance: even when a full steroid course is completed, the timing may be wrong. The optimal interval between corticosteroid administration and birth remains uncertain and may extend up to 14 days. Atosiban prolonged pregnancy beyond 48 hours much more often than placebo — but that prolongation may be insufficient to achieve the full benefits of the corticosteroid course.

Twin Pregnancies and Contraction-Stopping Drugs

The exchange also addresses twin pregnancies. The APOSTEL 8 trial included both singleton (one baby) and twin pregnancies, and experts questioned whether the results apply to twins. Data on the use of tocolytic drugs in twin pregnancies are limited, and the correspondents correctly point this out.

However, the trial authors defend their decision to include twins. No differential outcomes between singletons and twins have been reported, and the APOSTEL 8 study was designed as a pragmatic trial — one that reflects routine clinical practice. For that reason, they intentionally included a broad population of real-world patients.

Still, a subgroup analysis did suggest a possible difference in treatment effect between singletons and twins. That difference was not statistically significant (meaning it could have occurred by chance), so the trial authors state that their primary conclusion applies to the overall study population, not to twins specifically.

What the Experts Recommend

Both the correspondents and the trial authors converge on one big idea: it is time to re-evaluate treatment protocols for threatened preterm birth.

1. Optimize corticosteroid dosing. This includes testing reduced doses, half courses, and gestational age-tailored regimens rather than assuming one size fits all.
2. Evaluate tocolytic agents more carefully. Atosiban and other tocolytics should be studied according to specific indications, such as ruptured versus intact membranes (waters broken vs. not broken) and singleton versus multiple pregnancies.
3. Consider gestational age. Treatment decisions should be based on the baby's exact stage of development, since risks and benefits change from week to week.
4. Improve risk assessment. The trial authors state plainly that current clinical practice results in overtreatment — meaning many women receive interventions they may not need.
5. Follow children long-term. The planned 4-year follow-up of the APOSTEL 8 trial aims to provide more insight into the long-term outcomes of children exposed to these treatments before birth.

The correspondents emphasize that infants born between 30+0 and 33+6 weeks have a lower baseline risk of severe complications. These infants might genuinely benefit from reduced or individualized corticosteroid doses — but only robust, well-designed trials can confirm whether that approach is safer and equally effective.

Limitations to Keep in Mind

This exchange has important limitations. First, it is a set of expert letters and replies, not a new clinical trial. No new patients were treated, and no new data were generated. The opinions expressed are interpretations of existing published research.

Second, the APOSTEL 8 trial itself was not designed to assess the effectiveness of corticosteroids. The finding that more atosiban-treated participants completed a full steroid course — yet still did not have better newborn outcomes — is an interesting observation, but it cannot prove that steroids do not work after 30 weeks.

Third, much of the evidence cited comes from observational studies, which can show associations but cannot prove cause and effect. For example, the finding that over 1.25 million children exposed to corticosteroids had higher rates of mental and behavioral disorders does not prove the steroids caused those disorders. Many factors distinguish women who receive these drugs from those who do not.

Finally, the corticosteroid single-dose trial that failed to show non-inferiority had acknowledged methodological limitations, particularly in outcome selection. The scientific community has not yet reached a definitive answer.

What This Means for Patients

If you or someone you love faces threatened preterm birth between 30 and 34 weeks, this debate may feel alarming. What should you take away from it?

• Steroids are still the standard of care. Antenatal corticosteroids are not being abandoned. This exchange is about refining who gets them and at what dose — not about removing them from practice.
• Ask about your individual situation. Your doctor should weigh your exact gestational age, whether you are carrying one baby or more, and whether your waters have broken. The experts explicitly call for decisions based on these specific factors.
• Understand the trade-off. The potential benefit of steroids is better lung function and survival if your baby is born early. The potential risk is that animals and some human studies suggest possible long-term neurodevelopmental effects. A 4-year follow-up of APOSTEL 8 is planned to shed more light on this for children born after these treatments.
• Know what atosiban does — and does not do. Atosiban delays birth beyond 48 hours in about 78 in 100 women (78%), compared with about 69 in 100 women (69%) who receive placebo. That delay is meant to create time for steroids to work. It is not a cure for preterm birth, and in the APOSTEL 8 trial it did not by itself improve newborn outcomes.
• Consider clinical trials. The SNACS trial (NCT05114096) and other research efforts are actively seeking better answers. Patients who are eligible may wish to ask their doctors whether participating in such research is an option.

The central message from this exchange is hopeful in one important way: experts agree that "one-size-fits-all" obstetrics is no longer good enough. More personalized, better-studied approaches are coming. For now, women should have open, honest conversations with their care teams about the benefits, risks, and uncertainties of every intervention offered for threatened preterm birth.

Frequently Asked Questions

Are corticosteroid shots still recommended if I am at risk of giving birth between 30 and 34 weeks?

Yes, experts regard antenatal corticosteroids as the standard of care for threatened preterm birth. This exchange questions whether the standard full dose is always needed or whether reduced, more individualized dosing could be safer and equally effective at 30 to 34 weeks. Doctors should still offer steroids, but they should weigh your exact gestational age and discuss current uncertainty.

Why are doctors questioning corticosteroid shots after 30 weeks of pregnancy?

Doctors question the shots because most evidence comes from old trials done in the 1970s and 1980s, when babies at 30 to 34 weeks had higher risks. Modern studies suggest the benefit after 30 weeks may be smaller than once thought, while safety concerns about long-term child development have been raised. Experts now call for more research and possibly adjusted dosing.

What did the APOSTEL 8 trial find about the drug atosiban?

In 752 women with threatened preterm birth from 30 to nearly 34 weeks, atosiban delayed birth beyond 48 hours in 78% of women versus 69% with placebo. More atosiban-treated women also completed steroid shots. However, atosiban did not improve newborn outcomes. The extra delay may not matter if steroids themselves provide little benefit at this stage.

What are the possible risks of antenatal corticosteroids for my baby?

The article notes that animal studies have linked corticosteroid exposure to delayed fetal brain growth and impaired brain cortex development. Large human studies have reported higher rates of mental and behavioral disorders in children exposed before birth, including late-preterm and full-term infants. Researchers stress these associations do not prove cause, and many other factors may play a role.

Does the APOSTEL 8 result mean atosiban does not work?

No. Atosiban clearly worked to delay birth past 48 hours more often than placebo. However, delaying birth alone did not lead to better newborn health in this trial. The delay is meant to create time for steroids to work, but if steroid benefit after 30 weeks is uncertain, then more time may not improve baby outcomes. Atosiban is not a cure.

If I am pregnant with twins, do these findings apply to me?

The APOSTEL 8 trial included both singleton and twin pregnancies, and the authors defend this as reflecting real-world practice. No significant difference in outcomes between singletons and twins was found, but the authors state their main conclusion applies to the whole group, not specifically to twins. Experts agree that tocolytic use in twins needs more careful study.

What should I ask my doctor about treatments for threatened preterm birth at 30 to 34 weeks?

Ask how your exact gestational age affects the benefit and risk of steroid shots, whether your waters have broken, and if carrying twins changes the recommendation. Ask which tocolytic drug is being used and why, and whether the plan allows completing the full steroid course. Also ask if a reduced dose or a clinical trial might be an option.

I'm 32 weeks pregnant with threatened preterm labor — should I get a second opinion on the recommended steroid shots and atosiban?

Experts are re-evaluating whether the standard full course of antenatal corticosteroids still provides meaningful benefit between 30 and 34 weeks, and some now propose reduced or gestational age-tailored dosing. Safety concerns are dose-dependent, and studies have raised possible long-term neurodevelopmental risks. Atosiban delays birth beyond 48 hours more often than placebo, but in the APOSTEL 8 trial it did not improve newborn outcomes. A second opinion could help you weigh your exact gestational age, whether you carry twins, and whether your waters have broken. Diagnostic Detectives Network provides independent expert second opinions.

Source Information

This patient-friendly article is based on peer-reviewed research published in the correspondence section of The Lancet, Vol 406, September 27, 2025, pages 1339–1340.

• Original exchange title (as provided): "Atosiban for threatened preterm birth — the APOSTEL 10" (content refers to the APOSTEL 8 trial).
• Letter authors: Ruben Ramirez Zegarra (University Hospital Basel, Switzerland), Beatrice Valentini and Tullio Ghi (Fondazione Policlinico Universitario A Gemelli IRCCS, Rome, Italy); Lola Loussert and colleagues.
• Trial authors' reply: Larissa I van der Windt and Martijn A Oudijk (Amsterdam University Medical Center and Amsterdam Reproduction and Development Research Institute, Netherlands).
• Original trial referenced: van der Windt LI, et al. "Atosiban versus placebo for threatened preterm birth (APOSTEL 8): a multicentre, randomised controlled trial." Lancet 2025; 405: 1004–13.
• Authors' reply published online: August 11, 2025.

Key studies cited in this exchange include: Schmitz T, et al. Lancet 2022; 400: 592–604 (half-dose vs. full-dose betamethasone); Wapner RJ, et al. N Engl J Med 2007; 357: 1190–98 (repeat corticosteroid doses); Räikkönen K, et al. JAMA 2020; 323: 1924–33 (corticosteroids and mental/behavioral disorders); Ninan K, et al. JAMA Pediatr 2022; 176: e220483 (long-term outcomes meta-analysis).

Note: This article explains the scientific debate for educational purposes. It is not medical advice. Always discuss treatment decisions for threatened preterm birth with your obstetrician or midwife.