About 1 in 10 pregnant women with confirmed Zika infection in the United States had a fetus or baby with Zika-related birth defects in 2016, officials at the Centers for Disease Control and Prevention reported.
Among 972 completed pregnancies with laboratory evidence of possible recent Zika virus infection – 895 liveborn infants and 77 pregnancy losses – there were 51 fetuses/infants with Zika-related birth defects (5%). Among 250 pregnancies with laboratory-confirmed Zika infection, there were 24 cases of birth defects (10%). Among the 60 pregnancies in which Zika infection was confirmed and onset occurred during the first trimester, there were nine cases of birth defects (15%).
The data come from the CDC’s U.S. Zika Pregnancy Registry for 2016, which includes the 50 U.S. states, the District of Columbia, and all U.S. territories except Puerto Rico, which has its own registry.
“We are seeing about 30-40 new Zika cases in pregnant women each week in the United States. With the current tally of more than 1,600 pregnant women with evidence of Zika” reported in at least 44 states, mostly from travel to endemic areas, “this devastating outbreak is far from over,” CDC Acting Director Anne Schuchat, MD, said during an April 4 press conference.
But current birth defect estimates may not reflect the full impact of Zika virus in pregnancy, since some Zika-related developmental problems may not become apparent until months after birth. “We recommend babies receive close developmental monitoring and follow-up,” she said.
Despite CDC recommendations, one in three infants with possible congenital Zika infection had no report of Zika testing at birth, and only 1 in 4 had brain imaging ( Morb Mortal Wkly Rep. 2017 Apr 4. doi: 10.15585/mmwr.mm6613e1 ).
“Because the full clinical spectrum of congenital Zika virus infection is not yet known, all infants born to women with laboratory evidence of possible recent Zika virus infection during pregnancy should receive postnatal neuroimaging and Zika virus testing in addition to a comprehensive newborn physical exam and hearing screen,” the CDC officials wrote.
Birth defects – most commonly microcephaly or brain abnormalities – were reported in similar proportions of fetuses/infants whose mothers did and did not report Zika symptoms.
Dr. Schuchat noted that Zika virus can cause vision problems, hearing problems, and seizures. Some infants have little or no control over their arms or legs, and cannot reach out to touch things because of their constricted joints. There can be problems reaching developmental milestones, such as sitting up, as well as problems with feeding, swallowing, and breathing. Some babies cry inconsolably. Others may be born with a normal head size but experience slow head growth later on and develop microcephaly.
The study confirms the need for pregnant women to continue taking steps to prevent Zika virus exposure through mosquito bites and sexual transmission.
“We encourage [health care providers] to ask about possible Zika exposure when caring for both pregnant women and their babies, and to follow CDC guidance for evaluation and care of infants with possible Zika infection,” said Peggy Honein, PhD, senior investigator on the review, in a statement.
The mothers of the 51 fetuses or infants with birth defects were exposed to Zika during trips to 16 countries, including Barbados, Belize, Brazil, Cape Verde, Colombia, Dominican Republic, El Salvador, Guatemala, Guyana, Haiti, Honduras, Jamaica, Mexico, Puerto Rico, Republic of Marshall Islands, and Venezuela.