Abstract

Purpose This methodological systematic review aimed to identify and synthesise the existing under-five mortality (U5M) estimation methods globally. Methods We searched seven databases including Medline, Embase, Scopus, Web of Science, CINAHL, Global Health, and ProQuest Central, as well as grey literature sources from inception to September 25, 2025. The review protocol was prospectively registered in the International Prospective Register of Systematic Reviews (PROSPERO) (CRD42023465476). Results Fifty-six studies were included in this review. The most frequently employed child mortality estimation method was the indirect method (n = 16), followed by the Global Burden of Disease (GBD) study method (n = 12) and the direct method (n = 11). The most commonly applied models were spatiotemporal Gaussian process regression and the Bayesian B-spline bias-reduction model. Substantial variation was observed across studies in geographical scope, temporal coverage, data sources, uncertainty quantification, statistical modelling, and bias adjustment. Conclusions There are substantial variations in U5M estimation methods, with challenges in data availability, uncertainty estimation, and bias adjustment. These findings highlight the need to harmonise methodological approaches and refine estimation methods. Strengthening vital registration systems is essential to ensure accurate, reliable data to inform evidence-based decision-making and track progress towards U5M reduction targets.

Document Type

Journal Article

Date of Publication

1-1-2026

Volume

113

PubMed ID

41422875

Publication Title

Annals of Epidemiology

Publisher

Elsevier

School

School of Nursing and Midwifery / Nutrition and Health Innovation Research Institute / School of Medical and Health Sciences

RAS ID

88764

Funders

National Health and Medical Research Council / Western Australian Future Health Research and Innovation Fund (WANMA/EL2023–24/7, WANMA/Ideas2023–24/10) / Edith Cowan University Vice-Chancellor Research Fellowship

Grant Number

NHMRC Numbers : 1099655, 1173991, 1195716

Creative Commons License

Creative Commons Attribution 4.0 License
This work is licensed under a Creative Commons Attribution 4.0 License.

Comments

Kefale, B., Jancey, J., Gebremedhin, A. T., Belay, D. G., Pereira, G., & Tessema, G. A. (2025). Under-five mortality estimation methods: A methodological systematic review. Annals of Epidemiology, 113, 71–77. https://doi.org/10.1016/j.annepidem.2025.12.007

First Page

71

Last Page

77

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Link to publisher version (DOI)

10.1016/j.annepidem.2025.12.007