A Pew Research Center report on the changing demographics of American motherhood (discovered thanks to a tip by Michael Kimmel) shows that there has been a significant rise in childbearing among women at the later end of their childbearing years.
Not quite twice as many U.S. women over 35 gave birth in 2008 compared to 1990 (while we see the opposite trend for teen births):
The share of all births that were to women over 35 also increased from 9% to 14%:
A look at the birth rates across women from 15 to 44 shows that fewer women between 15 and 29 are giving birth, but the numbers are up for all women 30 and over.
The data broken down by race also suggests that it is white and Asian women who are driving this trend:
For more from this report, see our post on race trends in motherhood.