Among developed countries, average maternal age at first birth has been rising steadily in recent decades . In countries such as the United Kingdom (UK), Germany, and Korea, average maternal age at first birth is around 30. In England and Wales, the fertility rate from 1981 to 2012 decreased by about 30% among women aged between 20 and 24, but has doubled among women above 35 . In Japan, average maternal age at first birth increased from 24.4 in 1950 to 30.3 in 2013 .