157 pregnant women in U.S. have the Zika virus, CDC says

There are 157 U.S. cases of pregnant women who have the Zika virus, the Centers for Disease Control and Prevention said Friday. That's more than triple the previous number, due to both new cases and a change in how cases are reported, CNN reports.

So far, fewer than a dozen fetuses and babies have been affected, but most of the pregnancies reported are ongoing.

All U.S. patients with the mosquito-borne virus linked to birth defects have contracted it either abroad or sexually. That means there are no known cases of U.S. residents contracting Zika from mosquito bites.

Another 122 women in U.S. territories have contracted the Zika virus, according to the CDC.