Page 230 - GHES-3-1

Global Health Economics and
Sustainability

ORIGINAL RESEARCH ARTICLE
Fertility model evolution: A survey on

mathematical models of age-specific fertility
with application to Nepalese and Malaysian data

Arjun Kumar Gaire * , Yogendra Bahadur Gurung 1 , and Tara Prasad Bhusal 3
1,2
1 Central Department of Population Studies, Tribhuvan University, Kirtipur, Nepal
2 Department of Science and Humanities, Khwopa Engineering College, Purbanchal University,
Bhaktapur, Nepal
3 Central Department of Economics, Tribhuvan University, Kirtipur, Nepal

Abstract
Fertility pattern analysis and modeling to smooth age-specific fertility rates (ASFRs)
form a well-established research field that holds particular importance for Asian
countries. In developed nations, ASFRs typically display a bimodal skewed fertility
curve, whereas, in developing countries, they usually exhibit a unimodal skewed
Academic editor: fertility curve that diverges from the normal one. For decades, demographic experts
Mihajlo Jakovljevic M.D. Ph.D. MAE worldwide have been interested in creating models using deterministic and stochastic
approaches to represent these fertility curves. In this regard, parametric and non-
*Corresponding author:
Arjun Kumar Gaire parametric models have been created, with the latter providing a better fit for ASFR
(gaire.arjun@khec.edu.np) data. This research investigates the evolution of fertility models aimed at smoothing
Citation: Gaire, A.K., Gurung, Y.B. ASFRs. It explores suitable alternative models for countries with fast-declining,
& Bhusal, T.P. (2025). Fertility model unimodal, and skewed fertility curves of ASFRs, such as Nepal and Malaysia. Nepal’s
evolution: A survey on mathematical fertility rate is transitioning from a high level toward the replacement rate (2.1) at
models of age-specific fertility
with application to Nepalese and the year 2021; meanwhile, Malaysia’s fertility rate (1.7) in the year 2021 has dropped
Malaysian data. Global Health Econ below the replacement rate. Given the lack of a universally applicable model for ASFR
Sustain, 3(1):222-234. pattern variation, this study proposes the Kumaraswamy log-logistic distribution as
https://doi.org/10.36922/ghes.4219
a promising model to represent the ASFRs of Nepal and Malaysia accurately. Various
Received: July 11, 2024 approaches, including the Akaike information criterion, and Bayesian information
1st revised: August 18, 2024 criterion, are employed to validate the fitting of the proposed model.
2nd revised: September 12, 2024
Accepted: September 14, 2024 Keywords: Age-specific fertility rate; Parametric; Non-parametric; Malaysia; Nepal
Published online: November 11,
2024
Copyright: © 2024 Author(s). 1. Introduction
This is an Open Access article
distributed under the terms of the Women’s fertility represents their innate ability to have children. It is a fundamental
Creative Commons Attribution element of population growth, along with mortality and migration. Fertility and mortality
License, permitting distribution,
and reproduction in any medium, are biological factors, whereas migration is a socioeconomic factor. Age-specific fertility
provided the original work is rate (ASFR) is a fertility measure for a specific age group, typically expressed per thousand
properly cited. women in that age group in a particular locality. ASFRs depict the reproductive behavior
Publisher’s Note: AccScience of females in various age groups. Policymakers are concerned with women of specific age
Publishing remains neutral with groups concerning policies relating to reproductive rights and health, especially teenagers.
regard to jurisdictional claims in
published maps and institutional Although adolescence is widely accepted to be an inappropriate period for pregnancy, in
affiliations. Nepal, among women aged 15 – 49, more than 17% of them started having children in their

Volume 3 Issue 1 (2025) 222 https://doi.org/10.36922/ghes.4219