Very preterm babies who received a daily probiotic in the neonatal intensive care unit had markedly fewer deaths than those who did not.
The finding comes from a large Swedish study published September 23, 2026 in JAMA Network Open.
The combined risk of death or necrotizing enterocolitis, a severe bowel disease, was 0.8 percent among babies given the supplement.
Among those who did not receive it, the rate was 3.4 percent.
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Researchers at Karolinska Institutet in Stockholm tracked 4,695 infants born between 28 weeks and 31 weeks plus 6 days across Swedish neonatal units from 2017 to 2024.
Of those, 1,571 received probiotics and 3,124 did not.
The daily supplement combined three bacterial strains, Bifidobacterium infantis Bb-02, Bifidobacterium lactis BB-12, and Streptococcus thermophilus TH-4.
Together they delivered about 1 billion colony-forming units per dose.
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After statistical adjustment, the probiotic group had roughly 84 percent lower risk of death and 75 percent lower risk of necrotizing enterocolitis (often shortened to NEC).
The drop in the most severe, surgical form of the disease was even larger.
What the disease does
NEC is inflammation and tissue death of the bowel wall that mainly strikes premature infants.
It is the leading gastrointestinal emergency in the neonatal period and carries a mortality rate approaching 30 percent.
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Cases severe enough for surgery are even more dangerous.
Rates of sepsis, a bloodstream infection, were similar in both groups in the Swedish study.
The team emphasized that the study is observational. That means it can show an association, but cannot prove the supplement itself caused the improvement.
Ayoub Mitha, MD, PhD, of Karolinska Institutet, cautioned that the results do not apply to extremely preterm babies, those born before 28 weeks. That group was not part of the analysis.
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Why US practice looks so different
Sweden's neonatal society has recommended probiotics for babies born at 28 to 31 weeks since 2020, in line with European guidance.
In the United States, hospital practice is far less consistent.
A survey of level III and IV US NICUs found that 29.1 percent were giving preventive probiotics in early 2023, up from 14 percent in 2015.
That trend collapsed later the same year.
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When the researchers resurveyed 60 providers in December 2023, only 2 were still using the supplements.
The change followed a warning from the Food and Drug Administration.
The warning came after a preterm infant died from sepsis caused by Bifidobacterium longum.
Genetic testing tied the bacterium to Evivo with MCT Oil, a probiotic the baby had received in the hospital.
The FDA sent warning letters to Infinant Health and Abbott Laboratories in late September 2023, describing the products as unapproved new drugs.
Infinant voluntarily stopped shipping Evivo with MCT Oil.
The American Academy of Pediatrics still advises against routine probiotic use in preterm infants, particularly those with a birth weight below 1,000 grams.
Parents of a baby in the NICU can ask the medical team whether the unit uses a probiotic protocol and how it fits the baby's gestational age and weight.
This article is made and published by Ida-Marie Palm Varbæk, who may have used AI in the preparation.