The study of fertility dynamics has long sought to disentangle the drivers of changes in birth rates across time and space. One of the most significant advances in this area has been the identification of the so-called tempo effect of fertility, which highlights the role of changes in the timing of births in shaping observed fertility measures. First introduced systematically by demographer John Bongaarts in the late 1990s, the concept has reshaped how scholars interpret fluctuations in fertility rates, particularly in contexts of rapid demographic transition.
Read MoreGlobal birth rates are falling at an accelerated pace. According to the UN, the global total fertility rate (TFR) dropped to a record low of 2.25 in 2023 and is projected to fall further to 2.2 in 2024. At this pace, the TFR is set to dip below the replacement level of 2.1 nearly two decades earlier than the UN’s latest forecasts had anticipated.
The long-run decline in fertility has two main components. The first is the "quantum effect"—the trend for families to have fewer children as incomes rise, choosing instead to invest more in each child, particularly through education. Economics and evolutionary theory both rely on this shift in the quantity-quality trade-off to explain why fertility has fallen since the Industrial Revolution, even as wealth has grown.
The second component is the "tempo effect"—birth postponement. Women are delaying motherhood due to rising labour force participation and career opportunities, which increase the opportunity cost of having children, and shifting social norms. Other contributors include difficulty in finding a partner, precarious housing and job markets, and evolving personal preferences. Meanwhile, outright childlessness is increasing, which neither the quantum nor tempo frameworks fully explain.
Read MoreIt has been a while since I last delved into one of my favorite topics: global demographics. In this piece, I revisit the subject by examining high-level data on key global demographic indicators from the UN’s July 2024 Population Prospects database. I will begin with birth rates.
Scarcely a day goes by without an article, podcast, or both highlighting the accelerating decline in global fertility. As I explain in my essay on the fertility wars, this discussion tends to divide interlocutors into two increasingly polarized factions. On one side are those who believe falling fertility is a grave problem; on the other are those who remain more sanguine, viewing declining birth rates as a natural consequence of modernity—or perhaps postmodernism—and less of a threat to economic growth, government budgets, or humanity’s survival. If women choose to have fewer children and prioritize careers and personal freedom—long the exclusive domain of men—shouldn’t we support that choice?
Read MoreMy second audio essay is now up. You can listen and download the file directly here, or alternatively subscribe to ‘Alpha Source Audio Essay’ Apple Podcast channel where my future audio essays will also be published. The link to the episode on Apple podcasts is here.
You can find and download all my economics and demographics essays in written form here , as PDFs. You can find links to all references on the landing page for my demographics work here. I plan on doing once a month of these audio essays, time permitting, on demographics, economics, finance and everything in between.
Read More