Fertility rates have declined dramatically in most countries in Asia and Latin America in the last 50 y, with slower declines in sub-Saharan Africa (1, 2). For example, the total fertility rate (TFR), the number of children a woman would have over her lifetime if she experienced the age-specific fertility rates observed in a given year, fell from around 6.0 or higher to around or below the replacement rate of 2.1 between 1960 and 2019 in all of the nine large Asian and Latin American countries shown in Table 1 (1). In Bangladesh, the focus of this Commentary, the TFR fell from 6.9 in 1970 to 2.0 in 2019, a remarkable decline that few would have thought possible in the 1960s. As seen in Table 1, when fertility began to decline in these countries, usually in the 1970s, it fell at a rapid rate. Many factors contributed to these rapid fertility declines. Couples offset declines in infant and child mortality by having fewer births; access to family planning increased, allowing women to better choose the number and timing of births; rapid social and economic change, including urbanization and increases in women’s education, motivated parents to have fewer children and invest more in the health and education of those children (2).