If this slump in fertility is generational (i.e., late X'er/Millennial families choosing to delay marriage/childbirth) couldn't this all sort itself out with higher birthrates among the 35-45 age cohort sometime in the near future? Basically, the median age at first-marriage has been moving later faster than older couples are popping out kids?
This happened in the 90s/2000s. During the 70s, demographers were anticipating a giant echo-baby boom for the 80s...and it didn’t materialize. Instead births rose gradually.
Then they expected that women were having small families and predicted a major decline in births in the 90s. That didn’t materialize either as baby boomer women in their 30s and early 40s had children and immigrant fertility was high.
And then even as baby boomers passed out of child bearing years after 2000, births rose as Gen X women had slightly more children culminating in a record number of births in 2007 at 4.316 million, surpassing the record 4.308 million births in 1957. Then the numbers fell to just under 4 million by 2010, then were steady Between 3.9 and 4 million until 2017 when a more substantial decline began for 2017 and 2018.
This would seem to be the Trump baby bust more than anything. What makes it so substantial is that the largest cohort of people in this country are those born from 1988-1993...they are now 26-31 years old. Births should be rising...not seeing an accelerating decline.
That said the same thing happened in the 1920s and again in the early 70s. The women in the 20th century that had the most children were born in 1933...the nadir of the depression baby bust. And the women who hadmthe fewest were born around 1955, at the height of the baby boom and who came of age right as the oil crisis hit.