Nearly one in five American women in her early 40s is childless, according to a report that shows a striking increase in women who don't have biological children. The trend was much less common in the 1970s, when one in 10 women did not have children by 40 to 44, the age bracket researchers use to designate the end of childbearing years. The report, released Friday by the Pew Research Center, cites social and cultural shifts behind the change, including less pressure to have children, better contraceptive measures and expanded job opportunities for women. (snip) Overall, the report found that...