Toys R Us will close or sell each of its more than 700 locations in the US. In the company’s most recent annual filing, it cities declining birth rates as a threat to sales. Births have decreased rapidly since 2008 in the US, especially among millennial women. Toys R Us was one of the last national toy chains, and other similar retailers could be in trouble. Millennials are defined as those born between 1981 and 1996. They’re more college-educated and marry later than previous generations.