March 28, 2018
2 min read

Maternal Zika infection may cause brain, eye defects in 7% of children

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Photo of Margaret Honein
Margaret A. Honein

Neurologic and ocular birth defects occur in 7% of offspring of mothers located in French territories of the Americas who have lab-confirmed Zika virus infection, according to research published in The New England Journal of Medicine.

Additionally, defects were most likely to occur if the mother was infected with Zika in the first trimester of pregnancy.

“It has been recognized recently that Zika virus infection (ZIKV) during pregnancy can cause severe birth defects, including microcephaly, other brain defects and congenital Zika syndrome,” Bruno Hoen, MD, PhD, from the INSERM Centre d’Investigation Clinique 1424, and colleagues wrote. “However, the magnitude of this risk is not clearly defined. It was estimated to be higher than 40% in a prospective observational study in Brazil involving women who had symptomatic ZIKV infection during pregnancy.”

“In the U.S. Zika Pregnancy Registry, the estimate was 6% overall and 11% when ZIKV exposure occurred during the first trimester,” the researchers continued. “The latter estimate has been updated recently to 15%.”

To examine the risk of congenital neurologic defects associated with ZIKV in pregnant women who reside within French territories of the Americas, Hoen and colleagues conducted a prospective cohort study in which those with PCR assay-confirmed ZIKV were enrolled between March and November 2016. Data were collected until the last delivery was made on April 27, 2017.

Of the 546 pregnancies included in the study, 555 fetuses and infants were analyzed. Most were born alive (n = 527), with 5% of children not carried to term or were stillborn. Neurologic and ocular defects possibly caused by ZIKV were recorded for 7% of fetuses and infants (n = 39; 95% CI, 5.0-9.5). Of these 39 fetuses and infants, 10 were terminated before being carried to term for medical reasons, one was stillborn and 28 were carried to term and were born live.

Microcephaly, as defined by the researchers as a head circumference more than 2 SD under the average measurement for associated sex and weight, was observed in 32 fetuses and infants (5.8%). Nine of these children had a head circumference more than 3 SD below the average, constituting severe microcephaly.

When women were infected with ZIKV within the first trimester, neurologic and ocular defects were more commonly observed in offspring (12.7% of fetuses and infants). A lesser risk of neurologic and ocular defects was seen in offspring of mothers who were infected in the second trimester (3.6%) or third trimester (5.3%; P = .001).

“This report provides some of the most compelling data to date that the risk of brain abnormalities, microcephaly and eye anomalies extends to infections in every trimester of pregnancy,” Margaret A. Honein, PhD, MPH, from the National Center on Birth Defects and Developmental Disabilities at the CDC, said in a related editorial. “The findings in the French territories are remarkably similar to those in the U.S. Zika Pregnancy and Infant Registry, a surveillance network that monitors all pregnancies with laboratory evidence of ZIKV infection regardless of the presence or absence of maternal symptoms.”

“The approaches and lessons learned from the ZIKV outbreak in the Americas show the necessity of improved and integrated ongoing systems for surveillance of pregnancies, infectious diseases and birth defects to rapidly address the next emerging health threat affecting pregnant women and infants,” she continued. “Sustained commitment to better monitoring systems for these medically vulnerable populations will more promptly identify serious health threats and will provide an opportunity for the public health field to have a positive effect on infant health and prevent birth defects.”– by Katherine Bortz

Disclosures: Hoen and Honein report no relevant financial disclosures. Please see the study for a full list of all other authors’ relevant financial disclosures.