The pregnancies of six women in the U.S. who showed evidence of possible Zika virus infection resulted in birth defects, the Centers for Disease Control and Prevention said Thursday.
Three of the women delivered babies with birth defects and three others lost or terminated their pregnancies which had evidence of birth defects, the CDC said.
The CDC did not provide information on the timeline of these pregnancies and did not identify the women and children to protect their privacy.
Until now, the CDC had not reported on the total number of women in the U.S. whose pregnancies resulted in Zika-linked birth defects.
The agency said Thursday it would begin reporting on these numbers to "contribute to our understanding of the ongoing effect of Zika virus among pregnant women in U.S. and ensure that the most up-to-date information about pregnancy outcomes linked with Zika virus is publicly available."
The Zika-linked birth defects in the babies included microcephaly, a condition where the baby's head is smaller than expected and the baby often has smaller brains that may not have properly developed. Other defects included calcium deposits in the brain that indicated possible brain damage, excess fluid in the brain cavities, absent or poorly formed brain structures, abnormal eye development, and other problems resulting from brain damage.
The CDC said that while these defects occurred in pregnant women with laboratory evidence of the Zika virus infection, they could not say for certain that they were caused by the infection or by other factors.
The agency is monitoring 234 pregnant women with lab evidence of the Zika virus infection in the U.S. as of June 9.
"CDC's top priority for the Zika response is to protect pregnant women and women of childbearing age because of the potential risks associated with Zika virus infection during pregnancy," the agency said in a statement.