A Common Heart Vessel in Premature Babies: Why Doctors Often Choose to Wait

What the Baby-OSCAR study and its two-year follow-up found about treating a large "ductus" with ibuprofen

A large UK study called Baby-OSCAR followed 653 very premature babies who had a common heart-related condition, and it found that giving the medicine ibuprofen early — to close an open blood vessel near the heart — did not help babies survive better, breathe better, or develop better than giving a harmless dummy treatment [1]. When researchers checked the same children again at two years of age, the answer was still the same: no meaningful difference [2]. The medicine did close the vessel more often, but closing it did not make the babies healthier. This is reassuring news for families, because it means that watching and waiting — rather than rushing to medicate — is a sound, evidence-based choice.

What is this heart vessel?

Before a baby is born, a small blood vessel called the ductus arteriosus lets blood bypass the lungs, which are not yet being used because the baby gets oxygen from the placenta. In babies born at the right time, this vessel normally seals itself shut within a few days of birth. In babies born very early, it often stays open — a condition doctors call a patent (meaning "open") ductus arteriosus, or PDA. When it stays open and is large, extra blood flows through the lungs, which can add strain on the baby's heart and lungs [3].

Doctors have worried about the PDA for a long time because babies who have a large one still open in the first days of life tend to have more health problems — studies have found that a large open vessel on the third day of life is linked to a higher chance of serious complications [4]. But "linked to" is not the same as "the cause of." A key question hung over neonatology for decades: if we close the vessel, do the babies actually do better? Or is the open vessel just a marker that a baby is very sick, rather than the thing making them sick?

How families and doctors used to face this

For years there was no agreed answer, and expert reviews openly admitted that no approach — treating every baby early, waiting until problems appeared, or simply watching — had been proven to give babies a better long-term future [5]. Different hospitals did different things, and parents could be told very different plans depending on where their baby was cared for.

Earlier attempts to settle the question came up short. A large study of a related medicine, indomethacin, given to prevent problems, did reduce the open vessel and some bleeding in the brain but did not improve the children's survival or development by 18 months of age [6]. A trial that used heart ultrasound to find and treat large vessels early was too small to give a clear answer [7]. Another study comparing early medicine with a careful wait-and-see approach found no clear advantage to treating early [8]. And a study from the Netherlands, Belgium, and Denmark even suggested that babies left to be managed expectantly had less lung disease than those given early ibuprofen — a hint that early treatment might occasionally do more harm than good [9]. What was missing was a really large, carefully designed study focused on the babies with a genuinely large open vessel, using ultrasound to pick them out, and comparing early ibuprofen fairly against a dummy treatment. That is exactly what Baby-OSCAR set out to do.

What the researchers did

Between 2015 and 2020, doctors at 32 UK neonatal intensive care units invited families of very premature babies — born between 23 and 28 weeks of pregnancy — whose heart ultrasound in the first three days showed a large open vessel [1]. With parents' permission, each baby was randomly assigned, like the flip of a coin, to receive either a short course of ibuprofen (given into a vein) or an identical-looking dummy solution of sterile salt water. Neither the families, nor the doctors, nor the people later checking on the children knew which one any baby had received. This careful "blinding" is what makes the results trustworthy, because it removes the chance that expectations could tilt the findings. The children's health was then measured at 36 weeks and again at two years of age [2].

What they found

The medicine did its immediate job: about 56 out of every 100 treated babies had a closed or much smaller vessel by three weeks, compared with about 37 out of 100 in the dummy group [1]. But when it came to what really matters, the two groups looked the same. The chance of dying or developing serious chronic lung disease was actually slightly higher in the ibuprofen group (about 69 out of 100) than in the dummy group (about 64 out of 100) — not lower, as hoped. At two years of age, the share of children who survived without moderate or severe developmental problems was almost identical: about 53 out of 100 with ibuprofen and 52 out of 100 with the dummy [2]. Breathing outcomes at two years were also the same. In plain terms, closing the vessel earlier did not give these children a healthier start.

It helps to understand what "chronic lung disease" means here. Doctors call it bronchopulmonary dysplasia, or BPD, and it describes lungs that are still fragile and need extra oxygen or breathing support around the time the baby would otherwise have been due to be born. BPD is one of the most important challenges for very premature babies, which is why researchers hoped that closing the open vessel early might protect the lungs. The disappointment of Baby-OSCAR is that it did not — the babies given ibuprofen were, if anything, slightly more likely to die or have BPD, not less. Because so many babies were included and followed so carefully, families and doctors can be confident this is a real finding and not a fluke.

Another reason the results are trustworthy is the sheer scale and care of the study. Enrolling 653 babies across 32 hospitals over five years is a major undertaking, and following those children all the way to two years of age — with more than eight in ten seen again — is unusual and valuable. Many earlier studies were smaller and could only measure whether the vessel closed, not whether the child was healthier years later. Baby-OSCAR is one of the first to report on long-term breathing health after this kind of treatment, and it found no advantage. That combination of size, rigour, and long follow-up is what gives families a dependable answer rather than a hopeful guess.

It is worth being clear about one thing this study does not say. It does not say the PDA never matters or that medicine is never useful. It looked specifically at treating a large vessel early, before the baby had symptoms. Doctors still make individual decisions for babies who later become genuinely unwell from an open vessel — that situation was not what this study tested.

What this means for your baby

If your premature baby is found to have a large open ductus, this research supports a calm, watchful approach rather than an urgent rush to medicate. Many of these vessels close on their own or settle without early medicine, and the strongest evidence we now have shows that early ibuprofen does not improve survival, breathing, or development [1],[2]. When a care team chooses to watch and wait, that is not "doing nothing" — it is an active, thoughtful decision grounded in exactly this kind of high-quality evidence, and it also avoids exposing a baby to a medicine that, in some studies, carried possible downsides [9]. Ibuprofen and its relatives can close the vessel, but closing the vessel has not been shown to be what these babies need [10]. It is always fair to ask your baby's team what they are watching for and what signs would change the plan.

What researchers are working on next

Scientists are not finished with this question. They want to know what is best for the smaller group of babies whose large vessel stays open and starts causing problems after the first week of life — a situation Baby-OSCAR did not study [11]. The Baby-OSCAR team also plans to check in on these children again when they are 8 to 10 years old, to make sure no differences appear later in childhood, and to combine their results with other trials for an even clearer picture [9]. For now, families can take comfort in knowing that one of the largest, most careful studies ever done on this condition points toward patience, close monitoring, and treatment reserved for when it is truly needed. If your baby has an open ductus, it is completely reasonable to ask the care team how they are keeping an eye on it, what changes they would watch for, and what the plan would be if your baby's breathing or feeding changed. Being an informed, involved parent is one of the most valuable things you can do, and good neonatal teams welcome those questions.

References

  1. Gupta S, Subhedar NV, Bell JL, Field D, Bowler U, Hutchison E, et al. Trial of Selective Early Treatment of Patent Ductus Arteriosus with Ibuprofen. N Engl J Med. 2024;390(4):314–325. doi:10.1056/NEJMoa2305582 ↩
  2. Gupta S, O'Connor H, Juszczak E, Subhedar NV, Bowler U, Clarke C, et al. Two-year outcomes after selective early treatment of patent ductus arteriosus with ibuprofen in preterm babies: follow-up of Baby-OSCAR — a randomised controlled trial. eClinicalMedicine. 2025;87:103424. doi:10.1016/j.eclinm.2025.103424 ↩
  3. Hamrick SEG, Sallmon H, Rose AT, et al. Patent Ductus Arteriosus of the Preterm Infant. Pediatrics. 2020;146(5):e20201209. doi:10.1542/peds.2020-1209 ↩
  4. Sellmer A, Bjerre JV, Schmidt MR, et al. Morbidity and mortality in preterm neonates with patent ductus arteriosus on day 3. Arch Dis Child Fetal Neonatal Ed. 2013;98(6):F505–F510. doi:10.1136/archdischild-2013-303816 ↩
  5. Benitz WE; Committee on Fetus and Newborn, American Academy of Pediatrics. Patent Ductus Arteriosus in Preterm Infants. Pediatrics. 2016;137(1):e20153730. doi:10.1542/peds.2015-3730 ↩
  6. Schmidt B, Davis P, Moddemann D, et al. Long-term effects of indomethacin prophylaxis in extremely-low-birth-weight infants. N Engl J Med. 2001;344(26):1966–1972. doi:10.1056/NEJM200106283442602 ↩
  7. Kluckow M, Jeffery M, Gill A, Evans N. A randomised placebo-controlled trial of early treatment of the patent ductus arteriosus. Arch Dis Child Fetal Neonatal Ed. 2014;99(2):F99–F104. doi:10.1136/archdischild-2013-304695 ↩
  8. Clyman RI, Liebowitz M, Kaempf J, et al. PDA-TOLERATE Trial: An Exploratory Randomized Controlled Trial of Treatment of Moderate-to-Large Patent Ductus Arteriosus at 1 Week of Age. J Pediatr. 2019;205:41–48.e6. doi:10.1016/j.jpeds.2018.09.012 ↩
  9. Hundscheid T, Onland W, Kooi EMW, et al. Expectant Management or Early Ibuprofen for Patent Ductus Arteriosus. N Engl J Med. 2023;388(11):980–990. doi:10.1056/NEJMoa2207418 ↩
  10. Ohlsson A, Walia R, Shah SS. Ibuprofen for the treatment of patent ductus arteriosus in preterm or low birth weight (or both) infants. Cochrane Database Syst Rev. 2020;(2):CD003481. doi:10.1002/14651858.CD003481.pub8 ↩
  11. Gupta S, Subhedar NV, Bell JL, Bowler U, Clarke C, Cole C, et al. Outcome after Selective early treatment for Closure of patent ductus ARteriosus in preterm babies (Baby-OSCAR trial). Health Technol Assess. 2026;30(11). doi:10.3310/GJSG2422 ↩