Some 157 pregnant women in the United States and another 122 in U.S. territories have tested positive for infection with the Zika virus, the U.S. Centers for Disease Control and Prevention said on Friday.

It was the first time the agency had disclosed the number of Zika-infected pregnant women in the U.S. and its territories.

U.S. health officials have previously said that the virus, which is spread through mosquitos and sexual contact, can cause microcephaly, a birth defect marked by small head size that can lead to severe developmental problems in babies.

(Reporting by Ransdell Pierson; Editing by Chizu Nomiyama)