Being childless was considered unusual in the 1950s. Since then, the number of adults without children has increased. Many researchers say childfree adults are more educated, less likely to be religious and more likely to live around cities. In the late 2000s to early 2010s, the rate of women in the United States becoming pregnant dropped almost 9%. The birth rate between 2010 and 2013 was the lowest in the country's history.