According to a new study from the Pew Research Center, more United States women are having children later in life. While the overall birthrate in 2008 did not vary much from 1990, the number of babies born to women aged 35 and older rose a staggering 64 percent. The possible reason, notes report co- author Gretchen Livingston, is that younger people were more likely than older ones to cite the economic downturn as a reason to delay pregnancy.