US: 70% of women born in 1946 had a first child by 26, 31% of those born in 1997
In birth registers the slide runs from women born in 1973 (53%) rather than starting with Gen Z. The Atlanta Fed survey model gives Gen Z 26% and earlier generations 46–50%.
More
The blue line counts every first birth in the US, by the mother's birth year. Generation averages: boomers 58%, X 51%, millennials 42%, Gen Z (so far only 1997) 31%. For X, registers and survey nearly agree; for boomers and Gen Z the registers show more mothers by 26 than the survey.
Under the axis: the first birth years of boomers (1946), Gen X (1965), millennials (1981) and Gen Z (1997). An orange stroke is one survey number for the whole generation, drawn over its birth years; for Gen Z only over 1997: younger women are not 26 yet. Survey values are read off the paper's figure, to about 2 points.
- First child by age 26 % of women; year = birth year of women
1946: 70.4
- First child by age 26 % of women; year = birth year of women
1973: 52.6
- First child by age 26 % of women; year = birth year of women
1964: 51.6
- First child by age 26 % of women; year = birth year of women
1980: 49.1
- First child by age 26 % of women; year = birth year of women
1996: 31.9
- First child by age 26 % of women; year = birth year of women
1997: 30.8
- Survey: Baby boomers, 1946–1964 % of women, model
≈46%
Atlanta Fed working paper 2026-5, fig. 4(a): NSFG survey, model probability
- Survey: Generation X, 1965–1980 % of women, model
≈50%
Atlanta Fed working paper 2026-5, fig. 4(a): NSFG survey, model probability
- Survey: Millennials, 1981–1996 % of women, model
≈47%
Atlanta Fed working paper 2026-5, fig. 4(a): NSFG survey, model probability
- Survey: Generation Z, 1997–2012 % of women, model
≈26%
Atlanta Fed working paper 2026-5, fig. 4(a): NSFG survey, model probability
Registers: Human Fertility Database, cumulative first births per woman by the end of the year she turned 26 (26.5 on average), × 100 = share with a first child. Survey: Atlanta Fed working paper 2026-5, probability of having a child at 26 from the NSFG survey of women aged 20–40, a probit model holding race, education, partner and income constant.
Survey and registers measure different things: the survey model evens out the make-up of generations, registers count everyone. The survey sees 26-year-olds only from the 1980s, so early boomers are barely in it. Cohorts not yet 26 are not shown. The card says nothing about causes; the paper calls its own results suggestive.
A question for this picture
What does the same line look like in Japan, Spain or Sweden?