A routine probiotic given through a feeding tube was associated with a 51 percent lower risk of necrotizing enterocolitis in premature infants, according to a Dutch study published this week in JAMA Network Open. Necrotizing enterocolitis, usually shortened to NEC, is a sudden and often fatal intestinal disease and a major cause of illness and death among very premature babies.
The finding is meaningful for a condition with few prevention options. It also comes with a complication that parents and clinicians need to see up front rather than at the end: deaths from causes other than NEC were higher among the infants who received the probiotic.
Researchers from two Dutch academic centers, Erasmus Medical Center and Amsterdam University Medical Center, compared outcomes at two neonatal intensive care units before and after the units began routinely giving a formula containing three probiotic strains. NEC incidence fell from 11.9 percent to 5.3 percent, and after adjusting for gestational age, sex, birthweight, and prenatal corticosteroid use, the probiotic was associated with a 51 percent lower risk.
Reading the Mortality Signal Honestly
All-cause mortality did not change. It was 11.7 percent before the probiotic was introduced and 11.5 percent after, and mortality among the most extremely premature infants was also unchanged.
Within that flat total, the pattern shifted. Deaths not associated with NEC were higher in the group that received probiotics, 9.6 percent compared with 7.2 percent before implementation. One case of probiotic-associated sepsis occurred, meaning an infant developed a bloodstream infection involving the administered organisms.
The researchers did not treat that as a footnote. They wrote that the observed increase in non-NEC-associated mortality warrants cautious interpretation and further investigation, and called for future research to harmonize probiotic formulations, clarify strain-specific effects, and identify which infants are most likely to benefit.
The honest summary is that fewer babies developed NEC and roughly the same number of babies died. That is a real clinical gain if NEC is prevented without a corresponding harm elsewhere, and an unsettled question if it is not.
What the Study Design Can and Cannot Show
This was an observational before-and-after comparison, not a randomized trial. The study of two Dutch NICUs included 1,413 infants born between January 2018 and July 2024, with 598 in the period before routine use and 815 after. Routine administration began in October 2020 at one unit and March 2021 at the other. Baseline characteristics were similar, with mean gestational ages of about 27.7 and 27.9 weeks in the two groups.
Before-and-after designs are vulnerable to changes that happen over time for reasons unrelated to the intervention. Feeding practices, infection control, staffing and thresholds for diagnosing NEC can all shift across six years. Statistical adjustment reduces that problem but does not eliminate it.
The finding does align with earlier randomized evidence. An earlier randomized trial of the formulation found a 54 percent lower NEC risk among infants born before 32 weeks and weighing under about 3.3 pounds. The researchers said the comparable magnitude of association supports the formulation's effectiveness in practice.
The strains studied were Bifidobacterium infantis Bb-02, Bifidobacterium lactis BB-12, and Streptococcus thermophilus TH-4. Strain identity matters enormously here. Probiotic effects are strain-specific, and results from one formulation do not transfer to another product with a similar-sounding label. Two products can share a species name and behave differently in a newborn gut, which is one reason the researchers called for harmonized formulations before firmer conclusions are drawn.
The American Context Is Different from the Dutch One
This is where the story becomes practical for United States families. The multistrain formula used in the study has been endorsed by the European Society for Paediatric Gastroenterology Hepatology and Nutrition and is widely used in Europe. It is not standard practice in American NICUs.
Safety concerns are the reason, including rare cases of probiotic-associated sepsis. The American Academy of Pediatrics has cautioned against routine administration in the smallest infants, specifically those weighing less than about 2.2 pounds. The study authors noted that recent regulatory warnings, including from the FDA, have emphasized the need for robust data on both benefits and risks in this population.
MedicalDaily previously reported on the FDA warning issued after a preterm infant died of sepsis caused by the same bacterial species found in an administered probiotic. That warning has shaped American practice since.
No probiotic is FDA-approved as a drug for preventing NEC in preterm infants. Products sold as dietary supplements are not manufactured to pharmaceutical standards, and a supplement bought at a pharmacy is not the product studied here.
For parents, that means one thing above all: this is not a study that supports giving a premature baby a probiotic on a family's own initiative. Anything administered to an infant in intensive care goes through the neonatal team.
Parents of a baby currently in NICU care can reasonably ask the team what the unit's policy is on probiotics, whether the unit prioritizes human milk or pasteurized donor milk, which the pediatrics academy recommends for preterm infants, and what the unit's own NEC rate looks like. Those are answerable questions, and they are more useful than a supplement aisle.
What happens next is a regulatory and research question rather than a bedside one. Larger randomized trials with harmonized formulations would be needed to resolve the mortality signal, and American practice is unlikely to change without them. Current medical guidance has not changed, and no American professional body has revised its position in response to this study. Families weighing a NICU transfer or a second opinion should not treat probiotic availability as a deciding factor.
Key Questions Answered
What did the study find? A three-strain probiotic given routinely in two Dutch NICUs was associated with a 51 percent lower risk of necrotizing enterocolitis in premature infants.
What kind of study was it? An observational before-and-after comparison of 1,413 infants, not a randomized controlled trial. It shows an association, not proof of cause.
Did fewer babies die? No. All-cause mortality was essentially unchanged, and deaths from causes other than NEC were higher in the probiotic group.
What is necrotizing enterocolitis? A sudden inflammatory intestinal disease that mainly affects premature infants and is a major cause of illness and death in that group.
Is this probiotic used in American hospitals? Not routinely. The formulation is widely used in Europe, but American practice has been more cautious because of rare probiotic-associated infections.
Should parents buy a probiotic for a premature baby? No. Nothing should be given to an infant in intensive care outside the neonatal team, and store-bought supplements are not a studied product.
What should parents ask the NICU team? What the unit's probiotic policy is, whether human milk or donor milk is prioritized, and what the unit's NEC rate is.
