Could Gently Cooling a Premature Baby Help a Seriously Inflamed Bowel Heal?

A family-friendly look at a 2026 study from eight Brazilian hospitals by Gonçalves-Ferri and colleagues on mild cooling for babies with necrotising enterocolitis

Necrotising enterocolitis is a serious bowel illness that can affect very premature babies. A study from eight hospitals in Brazil found that babies with a moderate form of the illness who were gently cooled for two days at one hospital needed an operation less often, and died less often, than similar babies at seven other hospitals. Because the babies were not assigned to cooling by chance, the results are encouraging but are not yet proof.

If your baby was born very early, you may have heard staff mention "NEC" and watched them check your baby's tummy with extra care. This article explains what NEC is, why doctors have long wished for a better treatment, and what a new study of a simple idea, cooling the baby's body by about one and a half degrees, can and cannot tell us [1].

Why this bowel illness matters so much to premature babies

Necrotising enterocolitis, usually shortened to NEC, is an inflammation of the bowel in which parts of the intestine can become damaged and, in the worst cases, develop a hole. It mostly affects babies born very small, especially those weighing less than 1,500 grams (about 3 pounds 5 ounces), a group doctors call "very low birth weight". Research pooling information on more than half a million such babies found that about 7 in every 100 of them develop NEC [2]. NEC is one of the leading causes of death in neonatal intensive care units, the specialist hospital wards for sick newborns [3].

How families and doctors have faced NEC until now

For decades, the treatment of NEC has looked much the same. Since the 1980s, doctors have used a grading system, known as Bell staging, to describe how severe the illness is and to guide treatment [4]. When NEC is diagnosed, feeds are stopped so the bowel can rest, a thin tube drains the stomach, nutrition is given through a drip into a vein, and antibiotics are started. If the bowel develops a hole, the baby needs an operation [1]. A recent expert review noted that this approach has "changed minimally in the past 30 years", partly because the illness is not fully understood and there have been few treatment options [3]. Operations are common: across large studies, between about a quarter and a half of babies with NEC need surgery [1]. Surgery appears to add to the costs of care, and the extra hospital and medical care needed can continue for at least three years [5], and some children who survive bowel surgery later have problems such as a narrowed bowel (about 24 in 100) or difficulty absorbing enough food through the gut (about 13 in 100) [6]. For parents, this has meant days of waiting and watching, with little that anyone could actively do to stop the illness getting worse. The In[Neo]Sight article on the parental experience of NEC describes what that can feel like.

Where the idea of cooling came from

Cooling may sound like a strange thing to do to a tiny baby, and in everyday care it is the opposite of what nurses aim for. Babies who become cold by accident soon after birth do worse, and a large Brazilian study linked low temperature on arrival in intensive care with a higher chance of death in the first week [7]. Controlled cooling is different: it is planned, carefully measured and reversed slowly. It is already a standard treatment for full-term and near-term babies whose brains were short of oxygen around birth, where research showed it reduced death and disability [8]. Even so, cooling does not suit every baby; a study across 19 American hospitals found that it did not help babies born at 33 to 35 weeks of pregnancy with that same brain condition [9].

The idea of cooling for NEC began in the laboratory, where cooling protected the bowel of rats after its blood supply had been cut off and restored [10]. In a study published in 2010, doctors in London gently cooled 15 very sick premature babies with NEC for 48 hours and found it could be done without major problems [11]. A proper test followed, the CoolNEC trial (therapeutic controlled hypothermia for severe NEC) at Great Ormond Street Hospital for Children in London, United Kingdom, but it ended when its funding ran out after only 13 babies had joined [12]. A team in Ribeirão Preto, Brazil, then developed a simpler method that mainly involves switching off the incubator's heater. In their own hospital, 24 cooled babies needed surgery less often and none died, compared with 19 babies treated earlier without cooling [13], and the team reported no harmful side effects from the cooling [14].

How the new Brazilian study worked

The new study, published in 2026, included 285 premature babies weighing less than 1,500 grams who developed NEC between 2019 and 2023 in eight Brazilian neonatal units [1]. Every baby had signs of bowel trouble plus tiny gas bubbles in the bowel wall on an X-ray, which doctors call "pneumatosis" and which confirms NEC; the researchers called this "moderate" NEC.

At one hospital, 92 babies received the usual treatment plus cooling. A small temperature sensor was passed down the food pipe, and the baby's temperature was lowered slowly to about 35.5 °C, roughly 1.5 degrees below normal, for 48 hours, then slowly warmed again. Nurses checked temperature and other vital signs every 15 minutes, and babies received pain relief based on comfort scores. Parents gave written consent. At the other seven hospitals, 193 babies received the usual treatment at normal body temperature.

What the researchers found

Surgery was needed by about 14 in every 100 cooled babies (13 of 92), compared with about 46 in every 100 babies at the other hospitals (89 of 193). In-hospital deaths were also lower: about 23 in every 100 cooled babies (21 of 92) compared with about 35 in every 100 (67 of 193). After the researchers used statistical methods to account for differences such as birth weight and how early babies were born, the cooled babies' chance of needing surgery was about 3 in 10 of the other babies' chance, and their chance of dying in hospital was about 40% lower.

The researchers also looked at serious bleeding in the brain and a type of brain-tissue damage seen on ultrasound scans. These were seen in more cooled babies (about 11 and 15 in every 100) than in scanned babies at the other hospitals (about 6 and 10 in every 100). Because only a small number of babies were affected, these differences could have arisen by chance, so the study cannot say whether cooling is safe for the brain; also, some babies at the other hospitals died before they could be scanned. Cooled babies stayed in hospital longer, which the researchers put down to more of them surviving, although even the babies who survived stayed longer.

Why the results need careful reading

The most important thing to understand is that every cooled baby was at one hospital and every comparison baby was at a different hospital. Hospitals differ in many ways, including how quickly they diagnose NEC, when surgeons decide to operate and how babies are looked after day to day. Statistical adjustment can balance out differences that were measured, but not ones that were not [15], and a 2024 review notes that decisions about NEC surgery depend a good deal on the surgeon's experience [16]. So some or even much of the difference might be due to the hospital rather than the cooling. The study also did not report side effects of cooling, such as slow heart rate or bleeding, for these particular babies, nor how closely each baby's temperature stayed on target. The team's earlier, smaller study is the main reassurance about safety so far. The researchers themselves say cooling "may" help and that a randomised trial, in which babies are assigned to cooling or no cooling by chance, is needed.

What this means for your baby

For now, cooling for NEC is not a standard treatment, and most hospitals will continue the usual care of resting the bowel, giving antibiotics and nutrition through a vein, and calling surgeons when needed. If your baby has NEC, it is reasonable to ask the team about this research. They may explain that it is promising but unproven, and that outside a carefully planned research protocol, keeping premature babies warm remains an important part of their everyday care. Other helpful questions include how the team will keep your baby comfortable, how often the tummy will be checked with X-rays, and when the surgical team would become involved. Some signs, such as how a baby was doing in the first minutes after birth, help doctors judge how serious NEC may become [17], and your team can talk you through what those mean for your baby.

What researchers are working on next

The Brazilian team has followed the babies' development as they grow and is studying blood markers and other measurements. They estimate that a fair test would need several hundred babies in each group and say they are working to make such a trial possible [1]. Other new ideas for NEC are at an even earlier stage: one, called remote ischaemic conditioning, involves briefly and repeatedly tightening a cuff on a baby's limb, and its most recent safety study included only six babies [18].

The bottom line

Gentle cooling for two days is a simple, low-technology idea that has looked encouraging in Brazilian hospitals, with fewer operations and fewer deaths among babies with moderate NEC. Because the cooled babies were all in one hospital, and because questions about brain safety remain, doctors need a fair, randomised test before cooling can become part of everyday care.

References

  1. Gonçalves-Ferri WA, Sarri VC, Ferreira CHF, et al. Adjunctive mild controlled hypothermia for moderate necrotizing enterocolitis in very low birth weight infants: a prospective cohort study with external contemporaneous controls. Eur J Pediatr. 2026;185(11):799. doi:10.1007/s00431-026-07459-4 ↩
  2. Alsaied A, Islam N, Thalib L. Global incidence of Necrotizing Enterocolitis: a systematic review and Meta-analysis. BMC Pediatr. 2020;20(1):344. doi:10.1186/s12887-020-02231-5 ↩
  3. Hackam DJ, Modi N, Hulscher J, Kooi EMW, Ishiyama A. Necrotizing enterocolitis. Nat Rev Dis Primers. 2026;12(1):21. doi:10.1038/s41572-026-00698-7 ↩
  4. Walsh MC, Kliegman RM. Necrotizing enterocolitis: treatment based on staging criteria. Pediatr Clin North Am. 1986;33(1):179-201. doi:10.1016/S0031-3955(16)34975-634975-6) ↩
  5. Mowitz ME, Dukhovny D, Zupancic JAF. The cost of necrotizing enterocolitis in premature infants. Semin Fetal Neonatal Med. 2018;23(6):416-419. doi:10.1016/j.siny.2018.08.004 ↩
  6. Hau EM, Meyer SC, Berger S, Goutaki M, Kordasz M, Kessler U. Gastrointestinal sequelae after surgery for necrotising enterocolitis: a systematic review and meta-analysis. Arch Dis Child Fetal Neonatal Ed. 2019;104(3):F265-F273. doi:10.1136/archdischild-2017-314435 ↩
  7. de Almeida MF, Guinsburg R, Sancho GA, et al. Hypothermia and early neonatal mortality in preterm infants. J Pediatr. 2014;164(2):271-5.e1. doi:10.1016/j.jpeds.2013.09.049 ↩
  8. Jacobs SE, Berg M, Hunt R, Tarnow-Mordi WO, Inder TE, Davis PG. Cooling for newborns with hypoxic ischaemic encephalopathy. Cochrane Database Syst Rev. 2013;2013(1):CD003311. doi:10.1002/14651858.CD003311.pub3 ↩
  9. Faix RG, Laptook AR, Shankaran S, et al. Whole-Body Hypothermia for Neonatal Encephalopathy in Preterm Infants 33 to 35 Weeks' Gestation: A Randomized Clinical Trial. JAMA Pediatr. 2025;179(4):396-406. doi:10.1001/jamapediatrics.2024.6613 ↩
  10. Stefanutti G, Pierro A, Parkinson EJ, Smith VV, Eaton S. Moderate hypothermia as a rescue therapy against intestinal ischemia and reperfusion injury in the rat. Crit Care Med. 2008;36(5):1564-1572. doi:10.1097/CCM.0b013e3181709e9f ↩
  11. Hall NJ, Eaton S, Peters MJ, et al. Mild controlled hypothermia in preterm neonates with advanced necrotizing enterocolitis. Pediatrics. 2010;125(2):e300-308. doi:10.1542/peds.2008-3211 ↩
  12. Great Ormond Street Hospital for Children NHS Foundation Trust. Therapeutic Controlled Hypothermia in the Treatment of Neonates With Severe Necrotizing Enterocolitis (CoolNEC). ClinicalTrials.gov identifier NCT01330576. Status: terminated (end of funding); actual enrolment 13. Record last updated 2022-02-03. Accessed 2026-10-28. https://clinicaltrials.gov/study/NCT01330576 ↩
  13. Gonçalves-Ferri WA, Ferreira CHF, Couto LCA, et al. Low technology, mild controlled hypothermia for necrotizing enterocolitis treatment: an initiative to improve healthcare to preterm neonates. Eur J Pediatr. 2021;180(10):3161-3170. doi:10.1007/s00431-021-04014-1 ↩
  14. Gonçalves-Ferri WA, Ferreira CHF, Albuquerque LMS, et al. Mild controlled hypothermia for necrotizing enterocolitis treatment to preterm neonates: low technology technique description and safety analysis. Eur J Pediatr. 2022;181(9):3511-3521. doi:10.1007/s00431-022-04558-w ↩
  15. Austin PC, Stuart EA. Moving towards best practice when using inverse probability of treatment weighting (IPTW) using the propensity score to estimate causal treatment effects in observational studies. Stat Med. 2015;34(28):3661-3679. doi:10.1002/sim.6607 ↩
  16. Wang D, Zhang F, Pan J, Yuan T, Jin X. Influencing factors for surgical treatment in neonatal necrotizing enterocolitis: a systematic review and meta-analysis. BMC Pediatr. 2024;24(1):512. doi:10.1186/s12887-024-04978-7 ↩
  17. Kordasz M, Racine M, Szavay P, et al. Risk factors for mortality in preterm infants with necrotizing enterocolitis: a retrospective multicenter analysis. Eur J Pediatr. 2022;181(3):933-939. doi:10.1007/s00431-021-04266-x ↩
  18. Wu Y, Ganji N, Chen Z, et al. Remote ischemic conditioning in necrotizing enterocolitis: an extended phase I safety study. Pediatr Surg Int. 2025;42(1):47. doi:10.1007/s00383-025-06238-w ↩