A strange thing has happened to U.S. fertility patterns in recent decades. In the 1970s, there was little to no partisan difference in birthrates. This was an era when the total fertility rate was still hovering around the magic replacement level of 2.1"that is, the average woman could be expected to have 2.1 children across her lifetime, keeping the size of the population stable. The U.S. total fertility rate plummeted to a new low of 1.63 in 2024. A partisan fertility gap has emerged and seems to be growing. Conservatives have more children than liberals. They also are more likely to marry and marry younger. While Democrats are increasingly the party of the childless, Republicans are increasingly the party of parents.