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Am J Obstet Gynecol. 2018 Aug;219(2):187.e1-187.e20. doi: 10.1016/j.ajog.2018.04.047. Epub 2018 May 5.

Femur-sparing pattern of abnormal fetal growth in pregnant women from New York City after maternal Zika virus infection.

Author information

1
Division of Maternal-Fetal Medicine, University of Washington, Seattle, WA; Department of Obstetrics and Gynecology, University of Washington, Seattle, WA.
2
Division of Maternal-Fetal Medicine, Department of Obstetrics and Gynecology, Columbia University Medical Center, New York, NY.
3
Nuffield Department of Medicine, Center for Tropical Medicine and Global Health, University of Oxford, Oxford, United Kingdom; Center for Statistics in Medicine, Nuffield Department of Orthopedics, Rheumatology, and Musculoskeletal Sciences, University of Oxford, Oxford, United Kingdom.
4
Department of Radiology, University of Washington, Seattle, WA.
5
Department of Immunology, University of Washington, Seattle, WA; Department of Global Health, University of Washington, Seattle, WA; Center for Innate Immunity and Immune Disease, University of Washington, Seattle, WA.
6
Department of Pediatrics, University of Washington, Seattle, WA; Center for Innate Immunity and Immune Disease, University of Washington, Seattle, WA; Center for Global Infectious Disease Research, Seattle Children's Research Institute, Seattle, WA.
7
Nuffield Department of Obstetrics and Gynecology and Oxford Maternal and Perinatal Health Institute, Green Templeton College, University of Oxford, Oxford, United Kingdom.
8
Department of Obstetrics and Gynecology, University of Washington, Seattle, WA; Department of Global Health, University of Washington, Seattle, WA; Center for Innate Immunity and Immune Disease, University of Washington, Seattle, WA; Sahlgrenska Academy, Gothenburg University, Gothenburg, Sweden. Electronic address: adamsk@uw.edu.

Abstract

BACKGROUND:

Zika virus is a mosquito-transmitted flavivirus, which can induce fetal brain injury and growth restriction following maternal infection during pregnancy. Prenatal diagnosis of Zika virus-associated fetal injury in the absence of microcephaly is challenging due to an incomplete understanding of how maternal Zika virus infection affects fetal growth and the use of different sonographic reference standards around the world. We hypothesized that skeletal growth is unaffected by Zika virus infection and that the femur length can represent an internal standard to detect growth deceleration of the fetal head and/or abdomen by ultrasound.

OBJECTIVE:

We sought to determine if maternal Zika virus infection is associated with a femur-sparing pattern of intrauterine growth restriction through analysis of fetal biometric measures and/or body ratios using the 2014 International Fetal and Newborn Growth Consortium for the 21st Century Project and World Health Organization Fetal Growth Chart sonographic references.

STUDY DESIGN:

Pregnant women diagnosed with a possible recent Zika virus infection at Columbia University Medical Center after traveling to an endemic area were retrospectively identified and included if a fetal ultrasound was performed. Data were collected regarding Zika virus testing, fetal biometry, pregnancy, and neonatal outcomes. The 2014 International Fetal and Newborn Growth Consortium for the 21st Century Project and World Health Organization Fetal Growth Chart sonographic standards were applied to obtain Z-scores and/or percentiles for fetal head circumference, abdominal circumference, and femur length specific for each gestational week. A novel 2014 International Fetal and Newborn Growth Consortium for the 21st Century Project standard was also developed to generate Z-scores for fetal body ratios with respect to femur length (head circumference:femur length, abdominal circumference:femur length). Data were then grouped within clinically relevant gestational age strata (<24, 24-27 6/7, 28-33 6/7, >34 weeks) to analyze time-dependent effects of Zika virus infection on fetal size. Statistical analysis was performed using Wilcoxon signed-rank test on paired data, comparing either abdominal circumference or head circumference to femur length.

RESULTS:

A total of 56 pregnant women were included in the study with laboratory evidence of a confirmed or possible recent Zika virus infection. Based on the Centers for Disease Control and Prevention definition for microcephaly after congenital Zika virus exposure, microcephaly was diagnosed in 5% (3/56) by both the 2014 International Fetal and Newborn Growth Consortium for the 21st Century Project and World Health Organization Fetal Growth Chart standards (head circumference Z-score ≤-2 or ≤2.3%). Using 2014 International Fetal and Newborn Growth Consortium for the 21st Century Project, intrauterine fetal growth restriction was diagnosed in 18% of pregnancies (10/56; abdominal circumference Z-score ≤-1.3, <10%). Analysis of fetal size using the last ultrasound scan for all subjects revealed a significantly abnormal skewing of fetal biometrics with a smaller abdominal circumference vs femur length by either 2014 International Fetal and Newborn Growth Consortium for the 21st Century Project or World Health Organization Fetal Growth Chart (P < .001 for both). A difference in distribution of fetal abdominal circumference compared to femur length was first apparent in the 24-27 6/7 week strata (2014 International Fetal and Newborn Growth Consortium for the 21st Century Project, P = .002; World Health Organization Fetal Growth Chart, P = .001). A significantly smaller head circumference compared to femur length was also observed by 2014 International Fetal and Newborn Growth Consortium for the 21st Century Project as early as the 28-33 6/7 week strata (2014 International Fetal and Newborn Growth Consortium for the 21st Century Project, P = .007). Overall, a femur-sparing pattern of growth restriction was detected in 52% of pregnancies with either head circumference:femur length or abdominal circumference:femur length fetal body ratio <10th percentile (2014 International Fetal and Newborn Growth Consortium for the 21st Century Project Z-score ≤-1.3).

CONCLUSION:

An unusual femur-sparing pattern of fetal growth restriction was detected in the majority of fetuses with congenital Zika virus exposure. Fetal body ratios may represent a more sensitive ultrasound biomarker to detect viral injury in nonmicrocephalic fetuses that could impart long-term risk for complications of congenital Zika virus infection.

KEYWORDS:

INTERGROWTH-21st; Zika; biomarker; biometry; biparietal diameter; congenital Zika virus syndrome; femur length; fetal growth restriction; fetal infection; fetus; head circumference; intrauterine growth restriction; microcephaly; pregnancy; teratogenesis; ultrasound; virus

PMID:
29738748
PMCID:
PMC6066422
[Available on 2019-08-01]
DOI:
10.1016/j.ajog.2018.04.047

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