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. 2022 May;114(8):314-318.
doi: 10.1002/bdr2.1997. Epub 2022 Mar 25.

Identifying possible inaccuracy in reported birth head circumference measurements among infants in the US Zika Pregnancy and Infant Registry

Nicole M Roth  1 , Kate R Woodworth  1 , Shana Godfred-Cato  1 , Augustina M Delaney  1   2 , Samantha M Olson  1   3 , John F Nahabedian 3rd  2 , Megan R Reynolds  1 , Abbey M Jones  1 , Varsha Neelam  1 , Miguel Valencia-Prado  4 , Camille Delgado-López  4 , Ellen H Lee  5 , Esther M Ellis  6 , Heather Lake-Burger  7 , Julius L Tonzel  8 , Cathleen A Higgins  9 , Ronna L Chan  10 , Van T Tong  1 , Suzanne M Gilboa  1 , Janet D Cragan  1 , Margaret A Honein  1 , Cynthia A Moore  1
Affiliations

Identifying possible inaccuracy in reported birth head circumference measurements among infants in the US Zika Pregnancy and Infant Registry

Nicole M Roth et al. Birth Defects Res. 2022 May.

Abstract

Background: The US Zika Pregnancy and Infant Registry (USZPIR) monitors infants born to mothers with confirmed or possible Zika virus infection during pregnancy. The surveillance case definition for Zika-associated birth defects includes microcephaly based on head circumference (HC).

Methods: We assessed birth and follow-up data from infants with birth HC measurements <3rd percentile and birthweight ≥10th percentile to determine possible misclassification of microcephaly. We developed a schema informed by literature review and expert opinion to identify possible HC measurement inaccuracy using HC growth velocity and longitudinal HC measurements between 2 and 12 months of age. Two or more HC measurements were required for assessment. Inaccuracy in birth HC measurement was suspected if growth velocity was >3 cm/month in the first 3 months or HC was consistently >25th percentile during follow-up.

Results: Of 6,799 liveborn infants in USZPIR, 351 (5.2%) had Zika-associated birth defects, of which 111 had birth HC measurements <3rd percentile and birthweight ≥10th percentile. Of 84/111 infants with sufficient follow-up, 38/84 (45%) were classified as having possible inaccuracy of birth HC measurement, 19/84 (23%) had HC ≥3rd percentile on follow-up without meeting criteria for possible inaccuracy, and 27/84 (32%) had continued HC <3rd percentile. After excluding possible inaccuracies, the proportion of infants with Zika-associated birth defects including microcephaly decreased from 5.2% to 4.6%.

Conclusions: About one-third of infants in USZPIR with Zika-associated birth defects had only microcephaly, but indications of possible measurement inaccuracy were common. Implementation of this schema in longitudinal studies can reduce misclassification of microcephaly.

Keywords: Zika virus infection; birth defects; congenital Zika syndrome; microcephaly; population surveillance; pregnancy.

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Conflict of interest statement

CONFLICT OF INTEREST

The findings and conclusions in this report are those of the authors and do not necessarily represent the official position of the Centers for Disease Control and Prevention.

Figures

FIGURE 1
FIGURE 1
Live born infants in the US Zika Pregnancy and Infant Registry (USZPIR) with Zika-associated birth defects and classification of microcephaly using reported follow-up data. †38 infants with brain abnormalities and/or microcephaly also have reported eye abnormalities. ‡Microcephaly is defined as head circumference (HC) measurement at birth less than the 3rd percentile for gestational age and sex based on INTERGROWTH-21ST standards (INTERGROWTH-21st, 2020)
See this image and copyright information in PMC

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