Millennial Birth Rates. As recently as 2008, the total fertility rate in the U.S. was 2.1—meaning each woman was likely to have 2 children, enough to replace the population. That rate slipped below replacement levels in 2009 and kept falling. By 2020, the total fertility rate was 1.64, the lowest ever recorded (see Figure 5.32 in the Millennial chapter). When the birth rate is below replacement, the country tilts toward having more older people than younger ones.
