Effect of preterm birth on neonatal, infant, child, young adult and adult mortality: a systematic review and meta-analysis

OBJECTIVES: Preterm birth is associated with a higher risk of mortality. In 2020, the global incidence of preterm births was reported at 9.9 per 100 live births. This meta-analysis was undertaken to evaluate the effect of preterm birth on mortality among various age groups. METHODS: A thorough search was done on four electronic databases: "PubMed, Scopus, Web of Science, and Embase". Adhering to PRISMA 2020 guidelines, observational analytical studies published till 4th December 2024 were included. Screening of the studies was done by two independent reviewers in two stages: title/abstract, followed by full text review of the advanced articles. It was followed by data extraction. Study quality was assessed with the Newcastle Ottawa Scale. Meta-analysis using a random-effects model was done in R Studio. PROSPERO ID: CRD42024622282. RESULTS: Database search yielded 1775 unique studies. 23 studies met the final predefined eligibility criteria. Preterm babies showed an increased risk of mortality compared to term babies with a pooled relative risk of 6.12 (95 % CI: 3.16-11.84) for neonatal mortality, 11.84 (95 % CI: 6.88-20.37) for infant mortality and 1.88 (95 % CI: 1.24-2.83) for 1-5 year. However, it was similar in adult mortality with a pooled relative risk of 1.21 (95 % CI: 0.07-20.12). CONCLUSIONS: Preterm birth is strongly associated with increased risks of childhood mortality, especially in extreme and very preterm infants, but the risk persists even for late preterms.