The mortality rate for American mothers has more than doubled in the past 25 years. Kelly Wallace explains why. <script type='text/javascript' src='http://z.cdn.turner.com/cnn/van/resources/scripts/van-widgets.js'></script> <div data-cnnvansinglewidget data-affiliate='gantdaily' data-videoid='health/2015/11/19/surprising-facts-giving-birth-us-orig.cnn' data-size='auto' data-autostart='true'></div>