The number of pregnant women in Florida with the Zika virus climbed from nine to 36 following new federal guidelines outlining how the cases will be counted.
The Centers for Disease Control and Prevention is now asking states to report all pregnant women with evidence of Zika, regardless of whether or not they have symptoms.
In the past, the CDC publicly reported on only those women who had both positive lab tests as well as symptoms. But officials say recent research suggests that women do not necessarily have to have symptoms to have their pregnancies affected. So the CDC is expanding its reporting to include women who didn't have symptoms.
Nationally, more than 150 pregnant women in the United States appear to have been infected with Zika virus. That's in addition to more than 120 women affected by Zika in U.S. territories, mainly Puerto Rico.
Zika virus infection has been associated with miscarriage as well as birth defects like unusually small brains, called microcephaly. The exact risk posed by the virus remains unclear, and figuring that out is one reason the CDC is keeping track of affected pregnancies.
Information from NPR was used in this story.