The report, which collected its data from 3.79 million birth certificates, found the average birth rate dropped two percent since 2017—highlighting a steady decline since the Great Recession in 2007. Total fertility rate is the expected number of children a woman would have over her entire child-bearing lifetime—calculated as the ages between 15 and 44. In 2018, the fertility rate in the US was 1,729.5 births per 1,000 women. According to the CDC, replacement fertility rates are 2,100 births per 1,000 women. That means each woman needs to have at least two babies to replace the parents as well as account for early deaths.