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Am J Obstet Gynecol. 2015 Oct;213(4):449.e1-449.e41. doi: 10.1016/j.ajog.2015.08.032.

Racial/ethnic standards for fetal growth: the NICHD Fetal Growth Studies.

Author information

1
Division of Intramural Population Health Research, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD. Electronic address: louisg@mail.nih.gov.
2
Division of Intramural Population Health Research, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD.
3
Department of Obstetrics and Gynecology, Christiana Care Health System, Newark, DE.
4
Division of Maternal-Fetal Medicine, Department of Obstetrics-Gynecology, University of California, Irvine, School of Medicine, Irvine, and Fountain Valley Regional Hospital and Medical Center, Fountain Valley, CA.
5
Department of Obstetrics and Gynecology, Feinberg School of Medicine, Northwestern University, Chicago, IL.
6
Department of Obstetrics and Gynecology, Medical University of South Carolina, Charleston, SC.
7
Department of Obstetrics and Gynecology, Columbia University Medical Center, New York, NY.
8
Department of Obstetrics and Gynecology, New York Hospital Queens, Queens, NY.
9
Department of Obstetrics and Gynecology, Miller Children's Hospital/Long Beach Memorial Medical Center, Long Beach, CA.
10
Division of Maternal and Fetal Medicine, Department of Obstetrics and Gynecology, St Peter's University Hospital, New Brunswick, NJ.
11
Division of Maternal-Fetal Medicine, Department of Obstetrics and Gynecology University of Alabama, Birmingham, School of Medicine, Birmingham, AL.
12
Division of Maternal Fetal Medicine, Department of Obstetrics and Gynecology, Women and Infants Hospital of Rhode Island, Providence, RI.
13
Department of Obstetrics and Gynecology, Tufts Medical Center, Boston, MA.

Abstract

OBJECTIVE:

Fetal growth is associated with long-term health yet no appropriate standards exist for the early identification of undergrown or overgrown fetuses. We sought to develop contemporary fetal growth standards for 4 self-identified US racial/ethnic groups.

STUDY DESIGN:

We recruited for prospective follow-up 2334 healthy women with low-risk, singleton pregnancies from 12 community and perinatal centers from July 2009 through January 2013. The cohort comprised: 614 (26%) non-Hispanic whites, 611 (26%) non-Hispanic blacks, 649 (28%) Hispanics, and 460 (20%) Asians. Women were screened at 8w0d to 13w6d for maternal health status associated with presumably normal fetal growth (aged 18-40 years; body mass index 19.0-29.9 kg/m(2); healthy lifestyles and living conditions; low-risk medical and obstetrical history); 92% of recruited women completed the protocol. Women were randomized among 4 ultrasonography schedules for longitudinal fetal measurement using the Voluson E8 (GE Healthcare, Milwaukee, WI). In-person interviews and anthropometric assessments were conducted at each visit; medical records were abstracted. The fetuses of 1737 (74%) women continued to be low risk (uncomplicated pregnancy, absent anomalies) at birth, and their measurements were included in the standards. Racial/ethnic-specific fetal growth curves were estimated using linear mixed models with cubic splines. Estimated fetal weight (EFW) and biometric parameter percentiles (5th, 50th, 95th) were determined for each gestational week and comparisons made by race/ethnicity, with and without adjustment for maternal and sociodemographic factors.

RESULTS:

EFW differed significantly by race/ethnicity >20 weeks. Specifically at 39 weeks, the 5th, 50th, and 95th percentiles were 2790, 3505, and 4402 g for white; 2633, 3336, and 4226 g for Hispanic; 2621, 3270, and 4078 g for Asian; and 2622, 3260, and 4053 g for black women (adjusted global P < .001). For individual parameters, racial/ethnic differences by order of detection were: humerus and femur lengths (10 weeks), abdominal circumference (16 weeks), head circumference (21 weeks), and biparietal diameter (27 weeks). The study-derived standard based solely on the white group erroneously classifies as much as 15% of non-white fetuses as growth restricted (EFW <5th percentile).

CONCLUSION:

Significant differences in fetal growth were found among the 4 groups. Racial/ethnic-specific standards improve the precision in evaluating fetal growth.

KEYWORDS:

birthweight; epidemiology; estimated fetal growth; fetal growth; pregnancy

Comment in

PMID:
26410205
PMCID:
PMC4584427
DOI:
10.1016/j.ajog.2015.08.032
[Indexed for MEDLINE]
Free PMC Article

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