Roughly 5% of pregnant women with possible Zika virus infection in U.S. territories had a baby with related birth defects, according to federal health officials.
Birth defects were possible regardless of which trimester the woman was infected, and rates were consistent with earlier findings from U.S. states.
“Pregnant women may have continued exposure … in areas with known circulating Zika virus and, therefore, are at ongoing risk of infection,” said Anne Schuchat, M.D., acting director of the Centers for Disease Control and Prevention (CDC). “It is important that the health care and public health community remain vigilant to ensure infants receive the care they need.”
The new CDC report looks at data from pregnancy registries covering American Samoa, the Commonwealth of Puerto Rico, the Federated States of Micronesia, the Republic of Marshall Islands and the U.S. Virgin Islands. Each of these areas has reported local transmission of the virus.
From Jan. 1, 2016, to April 25, 2017, there were 2,549 completed pregnancies with lab evidence of recent possible Zika virus infection. Of those, 122 fetuses or infants (5%) were found to have Zika-related birth defects, the same rate reported in the states and Washington, D.C.
Rates were similar for both symptomatic and asymptomatic women as well as among confirmed and possible infections. Roughly 89% of the birth defects were brain abnormalities and/or microcephaly, according to the report.
Babies born to women confirmed to have been infected in the first trimester of pregnancy were found to have the highest rates of birth defects (8%), statistically similar to the states. The rates of birth defects linked to infection in the second and third trimesters were 5% and 4% respectively.
Roughly 52% of the infants had neuroimaging findings reported, surpassing the 25% reported in the states.
It is important to use brain imaging, such as ultrasound, at birth, because some babies have brain defects that are not evident, said Peggy Honein, Ph.D., M.P.H., co-lead of the CDC Zika Response’s Pregnancy and Birth Defects Task Force.
She also stressed the importance of following up, as some abnormalities don’t appear until months after birth.
“Identification and follow-up of infants with laboratory evidence of Zika virus infection during pregnancy can facilitate timely and appropriate clinical intervention services and help assess their future needs,” Dr. Honein said.
Pediatricians are urged to stay up-to-date on CDC recommendations and ask new families about potential exposure to Zika virus so they can facilitate the proper tests. They also should report suspected congenital Zika cases to their state, local, tribal or territorial health officials and provide clinical information to the U.S. Zika Pregnancy Registry or Puerto Rico Zika Active Pregnancy Surveillance System.