The Centers for Disease Control and Prevention said Friday that 279 pregnant women in the U.S. and its territories are now showing evidence of possible infection with the Zika virus, which may cause microcephaly or other severe birth defects in fetuses. Federal officials said that number is more than double those previously thought to be infected, as new procedures have been implemented to test and report the mosquito-borne virus. Many of the women have not developed symptoms or complications, CDC officials said. The U.S. states and District of Columbia reported 157 pregnant women with possible infections, with an additional 122 in federal territories, including Puerto Rico. Those numbers are through May 12. A majority of women infected with the virus never develop symptoms.