Despite evidence from randomized clinical trials and meta-analyses suggesting that the administration of probiotics is associated with reductions in necrotizing enterocolitis, sepsis, and mortality in very-low-birth-weight neonates, the extent of probiotic adoption and its effectiveness under clinical conditions remain unknown. A cohort study using data from a national network of U.S. neonatal ICUs (NICUs) investigated the diffusion and clinical benefits of probiotic use in very-low-birth-weight neonates in NICUs outside of a clinical trial context.

The sample included 307,905 very-low-birth-weight neonates who were treated at 807 NICUs between 2012 and 2019.

Nationally, probiotic use for neonates with very low birth weight increased slowly, from 4.1% of neonates with very low birth weight in 2012 to 12.6% of such neonates in 2019. In 2012, only 5.6% of hospitals treated at least 20% of their neonates who had very low birth weight with probiotics, whereas 16.5% of hospitals met this threshold by 2019. At hospitals that did adopt probiotic use, 76.3% of neonates with very low birth weight received probiotics in 2019.

The incidence of necrotizing enterocolitis declined by 18% at hospitals that adopted probiotics compared with nonadopting hospitals, but probiotic adoption wasn't associated with a significant reduction in sepsis or mortality.

The authors weren't able to investigate the reasons for the disparity between the efficacy of probiotics in clinical trials and their effectiveness in practice, but they point out that network data don't track the timing, dose, or formulation of probiotic feedings, all of which may affect potential benefits. They suggest that uncertainty about commercially available probiotics, which are not approved by the U.S. Food and Drug Administration, may contribute to lagging probiotic adoption rates.