Systematic estimates of global causes of neonatal and under 5 mortality in 2000-24: secondary data analysis using...

To estimate cause specific mortality among neonates and children under 5 for 195 countries from 2000 to 2024.

Secondary data analysis using a Bayesian multinomial logistic regression model to estimate cause specific mortality fractions.

PubMed, Embase, Web of Science, SCOPUS, Cochrane, Global Health Index Medicus, PAHO, Global Health OVID, Africa-Wide Information, IndMed, WHO Mortality Database, Demographic and Health Surveys (DHS), Multiple Indicator Cluster Surveys (MICS), and Health and Demographic and Surveillance Systems (HDSS).

Studies in the general population reporting empirical cause specific mortality for at least two causes in the age groups of interest, with a specified method for cause ascertainment. For studies identifying causes of mortality with verbal autopsy, ≥25 deaths reported with ≤25% of these deaths with unknown cause. For vital registration, ≥80% population completeness and ≤10% deaths assigned to ill defined causes determined by the international classification of diseases, 10th revision.

Cause specific mortality for countries with adequate quality vital registration was estimated with their own data with minor adjustments. For countries with low mortality without adequate quality vital registration, cause specific mortality was modeled by age group and based on vital registration. For high mortality areas, cause specific mortality was modeled primarily on the basis of verbal autopsy data identified in a systematic review. Estimated cause distributions were applied to all cause mortality rates and death counts estimated by the United Nations Inter-agency Group for Child Mortality Estimation. Among 4.9 million estimated global deaths in under 5s in 2024, the most important cause of death was preterm birth complications, with 0.82 (90% uncertainty interval 0.76 to 0.88) million deaths and 6.17 (5.93 to 6.42) deaths for every 1000 live births. This was followed closely by lower respiratory infections at 0.66 (0.60 to 0.71) million deaths, intrapartum related events (0.48 (0.43 to 0.52) million), and malaria (0.45 (0.39 to 0.51) million). Analysis for trends over time showed that the decline in most causes has slowed since 2016.

With the recent slowed pace of decline in under 5 mortality for most primary causes of death, many high mortality countries are at risk of missing the sustainable development goal targets of ≤12 neonatal deaths and ≤25 under 5 deaths per 1000 live births without acceleration. Estimates presented here can help countries to determine the most appropriate course of action to reduce under 5 mortality and achieve these targets.