I'm traveling, but I found some recent research released by the Census that I found interesting, but I'll admit is pretty irrelevant to most readers (some disclaimer!); apparently women are having substantially less children. Per the USA Today:
The number of women ages 40 to 44 who remain childless has doubled in a generation, the U.S. Census reported Monday.
In June 2006, 20% of women in that age group remained childless. Thirty years ago it was 10%.