From the National Center for Health Statistics: Births: Provisional Data for 2018. The NCHS reports:
The provisional number of births for the United States in 2018 was 3,788,235, down 2% from 2017 and the lowest number of births in 32 years. The general fertility rate was 59.0 births per 1,000 women aged 15–44, down 2% from 2017 and another record low for the United States. The total fertility rate declined 2% to 1,728.0 births per 1,000 women in 2018, another record low for the nation. Birth rates declined for nearly all age groups of women under 35, but rose for women in their late 30s and early 40s. The birth rate for teenagers aged 15–19 was down 7% in 2018 to 17.4 births per 1,000 women; rates declined for both younger (aged 15–17) and older (aged 18–19) teenagers.
Here is a long term graph of annual U.S. births through 2018.
Births have declined for four consecutive years following increases in 2013 and 2014.
With fewer births, and less net migration, demographics will not be as favorable as I was expecting a few years ago.
There is much more in the report.