Demographics might not be destiny, but it does make for great dinner-party chatter. More babies were born in the United States in 2007 than in any previous year, the Census Bureau reports. The nation's fertility level is at 2.1 percent - the replacement rate. The population won't be shrinking anytime soon. There are some disturbing trends in the census data, however. The rate of teen pregnancy has risen for the second straight year, and even though the rate of increase was small, it's a trend worth following. Also, more than 40 percent of women who had children in 2007 were unmarried. This is the highest level recorded yet, and may spell trouble for the futures of some of those kids. The latest upward trend in unmarried births started in 2002 and doesn't show signs of abating. In other demographic news, Americans stayed put from mid-2007 to mid-2008. Internal migration declined considerably. There was less moving around. And there were fewer immigrants. Put it all together, and the picture we get is of a growing country, but also a relatively stable one. People seem to be hunkering down and waiting for the financial storm to pass. And the two-parent family of married mother and father continues its transformation into something ... else.