tempo effects — Alpha.Sources

Delayed Gratification - Why are global birth rates falling, and does it matter?

This is the final chapter in the first part of my long-running demographics project. In the previous chapter I described the quantum effect of fertility, which hypothesises a negative relationship between fertility and rising incomes as parents substitute quantity for quality in their reproductive decisions and child-rearing. But can the quantum effect explain why birth rates in one country after the other appears to be stuck below the replacement level, and why global fertility will soon drop below that same level? The answer is no.

To understand current and more recent post WWII global fertility trends—broadly since the 1970s—we need to introduce tempo effects to the analysis. Tempo effects describe the tendency of women to postpone the timing of their first child. By mathematical logic, prolonged tempo effects can drive significant population ageing, but a more fundamental question is whether birth postponement also has a lagged effect on quantum, or more precisely, cohort fertility. This chapter discusses these question in the context of the hypothesis of a Second Demographic Transition, SDT, and presents a number of case studies to explore the specifics of recent fertility trends in key countries and regions. The chapter finishes by discussing the idea of a fertility trap, and whether the increasingly accelerating decline in global birth rates are a problem, drawing on the recent polarisation in the debate on this issue.

Japan's disappearing population

Japan invariably looms as the central case study for the economic and societal effects of rapid fertility decline, population decline and ageing. Japan is, measured by median age, the oldest country on earth, excluding the greying millionaires of Monaco and the some-5,000 people on British St. Helena. At the end of 2021, Japan had a median age of 48.4, well ahead of the second major country on the list, Italy, with a median age of 46.8. Japan is about to get older still. According to preliminary estimates, the country’s fertility rate fell further last year, albeit marginally, while the gap between births and deaths remained wide as ever. The number of live births fell by 5.0%, to 770.774, while deaths rose by 9.0%, to 1.57 million. Japan’s rapidly ageing population is the result of a quicker and more sustained post-1945 fertility transition than in other developed economies.

Who needs babies? In South Korea, no one…apparently

To the extent that birth postponement is a key feature of the second demographic transition, South Korea is a poster child for the phenomenon. Recently, we learned that South Korea's total fertility rate fell to an astonishing 0.78 in 2022, from 0.81 in 2021, the lowest period fertility rate on the planet. The first two charts paint a clear picture. The first shows the sustained decline in fertility rates, which began in the 1960s. In 1960, South Korean women were having about six children per women, a number which had declined to just over four by 1970 and just over two by 1980. By the middle of the 1980s, fertility fell below the replacement level, and the decline has continued since, despite temporary rebounds at the start of the 1990s and again at the beginning of the 2000s. Period fertility resumed its decline around 2015, and the result to date is that South Korea has the lowest recorded total fertility rate on earth. The second chart plots crude birth rate across age and 20-year time periods, which is a good way to distinguish between quantum and tempo effects.

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