According to the Centers for Disease Control and Prevention (CDC), about 6 percent of married women in the US are unable to get pregnant, and about 12 percent of women have difficulty getting pregnant or carrying a pregnancy to term, regardless of marital status.”What to do when someone who wants to have a child lacks gametes [eggs or sperm]?” one of the researchers in a new study, Carlos Simon from the Valencian Infertility Institute, said in a press statement. “This is the problem we want to address: to be able to create gametes in people who do not have them.”