Researchers reviewed over 50 studies about giving probiotics (helpful bacteria) to premature babies to see if they prevent serious infections. The good news: probiotics appear to reduce two major problems in premature infants—a dangerous gut condition called necrotizing enterocolitis and overall death rates. They may also slightly reduce late-onset infections, though the evidence is less clear. The risk of probiotics actually causing infections is extremely rare (less than 0.5%). Overall, the evidence suggests probiotics are safe and beneficial for premature babies, though scientists are still learning exactly how they work and which types work best.

The Quick Take

  • What they studied: Whether giving premature babies probiotic supplements (beneficial bacteria) helps prevent serious infections and other complications
  • Who participated: Analysis of over 50 randomized controlled trials involving premature infants, representing thousands of babies studied across multiple countries and medical centers
  • Key finding: Probiotics significantly reduced dangerous gut inflammation (NEC) and death rates in premature babies. They may slightly reduce late-onset infections (about 11% reduction), though the evidence is less certain. Serious side effects from probiotics are extremely rare—less than 0.5% of treated babies.
  • What it means for you: If you have a premature baby in the hospital, probiotics appear to be a safe option that may help prevent serious complications. However, talk with your baby’s doctors about whether probiotics are right for your specific situation, as individual cases vary.

The Research Details

This was a systematic review, meaning researchers looked at and analyzed all the best-quality studies (over 50 randomized controlled trials) that have been done on probiotics in premature babies. Randomized controlled trials are considered the gold standard in medical research because they randomly assign babies to either receive probiotics or a placebo (fake treatment) to see which group does better. By combining results from many studies, researchers can see patterns and get a clearer picture than any single study could provide.

The researchers examined whether probiotics actually prevent infections (especially late-onset sepsis, which is infection that develops after the first week of life), reduce other serious complications like necrotizing enterocolitis (a dangerous gut condition), and affect overall survival rates. They also looked carefully at safety—how often probiotics caused problems rather than helping.

This research approach is important because premature babies are very vulnerable and doctors need to know which treatments are truly safe and effective. By looking at all the high-quality studies together rather than just one study, researchers can see the real pattern of whether probiotics help or hurt. This gives doctors and parents much more reliable information for making treatment decisions.

This review is based on over 50 randomized controlled trials, which is the strongest type of evidence in medical science. The fact that multiple independent systematic reviews and meta-analyses (studies that combine many studies) all reached similar conclusions makes the findings more trustworthy. However, the evidence for preventing late-onset infections is rated as ’low certainty,’ meaning while there appears to be a benefit, scientists aren’t completely certain about the size of that benefit. The safety data is reassuring because serious problems from probiotics are documented as extremely rare across all these studies.

What the Results Show

The research shows that probiotics have clear benefits for premature babies in two important areas: they reduce necrotizing enterocolitis (a serious gut infection that can be life-threatening) and they reduce overall death rates. These are major findings because these complications are serious concerns in premature infant care.

Regarding late-onset sepsis (infections that develop after the first week), probiotics showed a modest benefit. The studies found about an 11% reduction in infection rates (relative risk of 0.89), meaning probiotics appear to help prevent some infections, but the effect is smaller than for the other benefits. Scientists rated this evidence as ’low certainty,’ meaning while the trend looks positive, they’re not completely confident in the exact size of the benefit.

The safety profile is very reassuring. Serious infections caused by the probiotics themselves occurred in less than 0.5% of treated babies—an extremely low rate. This means that while there’s a theoretical risk that probiotics could cause infection, in practice this is exceptionally rare.

The research suggests probiotics work through several mechanisms: they compete with harmful bacteria for space in the gut, strengthen the gut barrier so bacteria can’t enter the bloodstream, boost the baby’s immune system, and help babies start eating sooner (which reduces the need for intravenous lines where infections can enter).

Beyond the main findings, researchers noted that product quality varies—some probiotic supplements may be contaminated or not contain what they claim. However, with proper quality control and testing, these issues appear manageable. The studies also suggest that different strains (types) of probiotics may have different effects, and scientists are still learning which specific strains work best for which outcomes.

This review confirms and strengthens what previous research has suggested: probiotics appear to be one of the most beneficial interventions available for premature infants, particularly for preventing necrotizing enterocolitis and reducing death rates. The findings align with multiple Cochrane systematic reviews (which are considered among the highest quality reviews in medicine). The modest effect on late-onset infections is consistent with earlier findings, suggesting this is a real but smaller benefit compared to the effects on gut complications.

The main limitation is that while there’s strong evidence for benefits against necrotizing enterocolitis and mortality, the evidence for preventing late-onset infections is less certain. Scientists also note that most studies used different probiotic strains, making it hard to say which specific types work best. Additionally, the long-term effects of probiotics on babies’ developing immune systems and antibiotic resistance aren’t fully understood yet. Finally, while the safety data is reassuring, very rare serious side effects might not show up in current studies simply because they’re so uncommon.

The Bottom Line

Based on current evidence, probiotics appear to be a reasonable option for premature infants, particularly for preventing serious gut complications and reducing death rates (high confidence in these benefits). The modest benefit for preventing late-onset infections is less certain but still appears positive (low to moderate confidence). The safety profile is reassuring, with serious side effects being extremely rare. Parents and doctors should discuss whether probiotics are appropriate for an individual baby, considering the specific medical situation.

This research is most relevant for parents of premature babies, neonatal doctors and nurses, and healthcare systems caring for premature infants. It’s particularly important for babies born very early (before 37 weeks), as they face the highest risk of these complications. Babies born at full term or those without risk factors for these complications may have different considerations. Anyone considering probiotics for a premature baby should discuss it with their medical team.

Benefits from probiotics typically develop over days to weeks as the bacteria establish themselves in the baby’s gut. The protective effects against serious gut complications appear to develop gradually as the gut barrier strengthens. Parents shouldn’t expect immediate changes but rather gradual improvement in feeding tolerance and reduced infection risk over the course of hospitalization.

Want to Apply This Research?

  • If a premature baby is receiving probiotics, track daily feeding progress (volume tolerated), any signs of infection (fever, feeding intolerance, lethargy), and dates of any infections that develop. This helps parents and doctors see whether the baby is progressing as expected.
  • For parents of premature babies: work with your medical team to understand if probiotics are recommended for your baby, ensure the probiotic product used meets quality standards, and maintain open communication with doctors about any concerns or changes in your baby’s condition.
  • Long-term tracking should include monitoring feeding progression, infection rates during hospitalization, and overall health outcomes. Parents should keep records of which probiotic strain was used and any side effects observed, as this information helps doctors understand what works best for individual babies.

This summary is based on a systematic review of research and is for informational purposes only. It does not replace professional medical advice. Decisions about probiotic supplementation for premature infants should only be made in consultation with qualified healthcare providers who know the baby’s specific medical situation. While the research suggests probiotics are generally safe and beneficial for premature babies, individual cases may vary. Parents should discuss the potential benefits and risks with their neonatal care team before starting any supplements. This information is current as of the publication date but medical understanding evolves; always consult with your healthcare provider for the most up-to-date guidance.