Top 5 Takeaways

1. Prevalence of Birth Defects: Approximately 5% of infants in the U.S. Zika Pregnancy and Infant Registry (USZPIR) had Zika-associated brain or eye defects.
2. Common Defects: Frequently reported defects included microcephaly, corpus callosum abnormalities, intracranial calcification, and optic nerve abnormalities.
3. Multiple Defects: One third of infants with any Zika-associated birth defect had more than one defect reported.
4. Trimester Impact: Higher frequency of birth defects was observed in infants born to mothers infected in the first and second trimesters compared to the third trimester.
5. Surveillance Implications: Certain brain and eye defects in infants might signal prenatal Zika virus infection and could indicate the reemergence of Zika virus in areas without comprehensive surveillance.

Original Article Author and Citation

Corresponding Author

Nicole M. Roth, setnet@cdc.gov

Suggested Citation

Roth NM, Reynolds MR, Lewis EL, et al. Zika-Associated Birth Defects Reported in Pregnancies with Laboratory Evidence of Confirmed or Possible Zika Virus Infection — U.S. Zika Pregnancy and Infant Registry, December 1, 2015–March 31, 2018. MMWR Morb Mortal Wkly Rep 2022;71:73–79. DOI: http://dx.doi.org/10.15585/mmwr.mm7103a1

Summary

This study from the U.S. Zika Pregnancy and Infant Registry (USZPIR) reports on the frequency of individual Zika-associated brain and eye defects among infants born from pregnancies with laboratory evidence of confirmed or possible Zika virus infection. Approximately 4.6% of live-born infants had any Zika-associated birth defect, with a higher percentage (6.1%) in those with a positive nucleic acid amplification test (NAAT) for Zika virus. Common defects included microcephaly, intracranial calcification, and optic nerve abnormalities. One third of affected infants had multiple defects.

Methods

Data were collected from the USZPIR, which included mother-infant linked longitudinal surveillance of outcomes in pregnant women and infants with laboratory evidence of Zika virus infection. Information was gathered from medical records and reviewed by subject matter experts. The study analyzed data from 6,799 live-born infants and 325 pregnancy losses, examining the frequency of Zika-associated birth defects by trimester of exposure, maternal symptom status, and location of birth.

Discussion

The findings highlight the significant impact of Zika virus infection during pregnancy on infant health, particularly brain and eye defects. The study underscores the importance of targeted surveillance for these defects to identify potential Zika virus reemergence. The similar frequency of birth defects among symptomatic and asymptomatic pregnant women suggests that all pregnant women with potential Zika exposure should be monitored.

Conclusion

This report provides critical insights into the prevalence and types of Zika-associated birth defects. Continued surveillance and research are necessary to fully understand the spectrum of Zika-associated outcomes and to improve monitoring and prevention strategies for future outbreaks.

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