Three babies have been born in the United States with Zika virus-related birth defects, according to figures released today by the Centers for Disease Control and Prevention. The report noted an additional three "pregnancy losses with birth defects" in Zika-infected mothers.

Since Zika was declared a public health emergency by the World Health Organization five months ago, doctors have been working to understand and track the disease. This is the first time the CDC has reported any pregnancy losses or babies born in the United States with Zika-related defects, according to Stat.

The data in the CDC's report is from last week, and the agency updates it weekly with anonymized information about any pregnancies where the mother has "laboratory evidence of possible Zika virus infection." Data comes from the US Zika Pregnancy Registry, a system created by the CDC to track reported infections in pregnant women, and the outcomes of their pregnancies.

Birth defects can include microcephaly and nerve damage

In mid-April the CDC confirmed that women with Zika virus, especially those who become infected early in pregnancy, may give birth to babies with abnormally small heads — a condition called microcephaly. Zika is transmitted via mosquitos or sexual intercourse, and since early this year it was suspected to cause a range of birth defects.

The CDC's announcement today did not specify which birth defects the three babies were born with. It simply stated that they included "microcephaly, calcium deposits in the brain indicating possible brain damage, excess fluid in the brain cavities and surrounding the brain, absent or poorly formed brain structures, abnormal eye development, or other problems resulting from damage to brain that affects nerves, muscles and bones, such as clubfoot or inflexible joints."

The report also did not make clear whether the three pregnancy losses in women infected with Zika were voluntary terminations or miscarriages.

So far, 234 pregnant women in the United States and 189 in US territories have been diagnosed with Zika virus, Stat noted.