Researchers at Karolinska Institutet analysed Swedish neonatal register data on 4,695 very preterm babies born between 2017 and 2024. Of these, 1,571 received a probiotic supplement containing three bacterial strains and 3,124 did not.
Death or necrotising enterocolitis, a serious intestinal disease, occurred in 0.8% of babies given probiotics, compared with 3.4% in the other group. Deaths stood at 0.3% versus 1.4%, and enterocolitis cases at 0.6% versus 2.5%. The sepsis rate, however, was similar in both groups.
Since 2020, the Swedish Neonatal Society has recommended daily probiotics for babies born between 28 and 31 weeks of gestation. Because the study is observational, it shows associations rather than cause and effect, and lead author Ayoub Mitha warns that the results should not be generalised to babies born before 28 weeks, who were not included.
The work was published in the journal JAMA Network Open.
