Background: In the last several decades, notwithstanding its historical and biological stability, the sex ratio at birth (SRB) has risen in various parts of the world. The resultant demographic consequences are well documented and typically include ‘missing girls/women’ and the ‘marriage squeeze.’ However, the underlying mechanism and impact of the SRB on demographic dynamics have not been explored in depth. Objective: In this study, we investigate the impact of a rise in the SRB on the size, structure, and growth of a population, with a focus on population aging. Methods: We develop a simple methodological framework derived from classical stable population models to analyze how a rise in the SRB reduces population size and ages a population. Results: Cohorts born with a higher SRB are smaller than those born with a lower SRB. The smaller size of these cohorts leads to a reduction in the total population size, thereby increasing the proportion of cohorts of older persons born during periods with a lower SRB that are the same size as earlier cohorts. As cohorts continue to be born during the period with the higher SRB, their proportion in the population increases and the process of population aging accelerates. Contribution: This study shows that, in addition to fertility and mortality, the SRB can be a driving factor in population dynamics, especially when it rises well above normal biological levels.

中文翻译：

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出生时性别比上升引起的人口老龄化

背景：在过去的几十年中，尽管其历史和生物学上的稳定性，但世界各地出生时的性别比（SRB）仍在上升。由此产生的人口后果有据可查，通常包括“失踪的女孩/妇女”和“挤婚”。但是，尚未深入探讨SRB对人口动态的潜在机制和影响。目的：在这项研究中，我们调查了SRB上升对人口规模，结构和增长的影响，重点是人口老龄化。方法：我们开发了一个从经典稳定人口模型得出的简单方法框架，以分析SRB的上升如何减少人口规模和人口年龄。结果：出生率较高的人群比出生率较低的人群要小。这些队列的较小规模导致总人口规模的减少，从而增加了在SRB较低的时期出生的老年人的队列比例，该年龄与早期队列相同。由于在SRB较高的时期继续出生的人群，其在人口中的比例增加，人口老龄化进程加快。贡献：这项研究表明，除了生育率和死亡率外，SRB可能是种群动态的驱动因素，尤其是当其上升到远高于正常生物学水平时。由于在SRB较高的时期继续出生的人群，其在人口中的比例增加，人口老龄化进程加快。贡献：这项研究表明，除了生育率和死亡率外，SRB可能是种群动态的驱动因素，尤其是当其上升到远高于正常生物学水平时。由于在SRB较高的时期继续出生的人群，其在人口中的比例增加，人口老龄化进程加快。贡献：这项研究表明，除了生育率和死亡率外，SRB可能是种群动态的驱动因素，尤其是当其上升到远高于正常生物学水平时。