TOKYO - Some 37.8 percent of women aged between 25 and 49 years in Japan have experienced or are experiencing infertility partly because more couples choose to have children later in life, a university study found Tuesday.

By comparison, the World Health Organization estimates 17.5 percent of the global adult population experience infertility, which is defined as the "failure to achieve a pregnancy after 12 months or more of regular unprotected sexual intercourse."