Pregnancy Outcomes after ZIKV Infection in French Territories in the Americas

N Engl J Med. 2018 Mar 15;378(11):985-994. doi: 10.1056/NEJMoa1709481.


Background: The risk of congenital neurologic defects related to Zika virus (ZIKV) infection has ranged from 6 to 42% in various reports. The aim of this study was to estimate this risk among pregnant women with symptomatic ZIKV infection in French territories in the Americas.

Methods: From March 2016 through November 2016, we enrolled in this prospective cohort study pregnant women with symptomatic ZIKV infection that was confirmed by polymerase-chain-reaction (PCR) assay. The analysis included all data collected up to April 27, 2017, the date of the last delivery in the cohort.

Results: Among the 555 fetuses and infants in the 546 pregnancies included in the analysis, 28 (5.0%) were not carried to term or were stillborn, and 527 were born alive. Neurologic and ocular defects possibly associated with ZIKV infection were seen in 39 fetuses and infants (7.0%; 95% confidence interval, 5.0 to 9.5); of these, 10 were not carried to term because of termination of pregnancy for medical reasons, 1 was stillborn, and 28 were live-born. Microcephaly (defined as head circumference more than 2 SD below the mean for sex and gestational age) was detected in 32 fetuses and infants (5.8%), of whom 9 (1.6%) had severe microcephaly (more than 3 SD below the mean). Neurologic and ocular defects were more common when ZIKV infection occurred during the first trimester (24 of 189 fetuses and infants [12.7%]) than when it occurred during the second trimester (9 of 252 [3.6%]) or third trimester (6 of 114 [5.3%]) (P=0.001).

Conclusions: Among pregnant women with symptomatic, PCR-confirmed ZIKV infection, birth defects possibly associated with ZIKV infection were present in 7% of fetuses and infants. Defects occurred more frequently in fetuses and infants whose mothers had been infected early in pregnancy. Longer-term follow-up of infants is required to assess any manifestations not detected at birth. (Funded by the French Ministry of Health and others; number, NCT02916732 .).

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adolescent
  • Adult
  • Amniotic Fluid / virology
  • Chromosome Disorders / epidemiology
  • Cohort Studies
  • Congenital Abnormalities / epidemiology*
  • Female
  • Fetal Diseases / epidemiology
  • French Guiana / epidemiology
  • Guadeloupe / epidemiology
  • Humans
  • Infant, Newborn
  • Martinique / epidemiology
  • Microcephaly / epidemiology*
  • Middle Aged
  • Pregnancy
  • Pregnancy Complications, Infectious*
  • Pregnancy Outcome / epidemiology*
  • Pregnancy Trimesters
  • Young Adult
  • Zika Virus / isolation & purification
  • Zika Virus Infection / complications*
  • Zika Virus Infection / epidemiology

Associated data