Prenatal application of the individualized fetal growth reference.
The individualized reference for defining small for gestational age (SGA) at birth has gained popularity in recent years. However, its utility on fetal assessment has not been evaluated. The authors compare an individualized with an ultrasound reference in predicting poor perinatal outcomes. Data from a large clinical trial in predominantly white US women (1987-1991) with singleton pregnancies (n = 9,526) were used. The individualized reference classified fewer SGA fetuses than the ultrasound reference, but the risks of adverse outcomes were similar between fetuses classified by both references. The risk increased substantially only when the percentiles fell below the 5th percentile (likelihood ratio positive at birth = 2.68 (95% confidence interval (CI): 2.00, 3.58) and 3.13 (95% CI: 2.34, 4.18) for ultrasound and individualized references, respectively). SGA fetuses defined by either the individualized or ultrasound reference alone had risk ratios of adverse outcomes of 1.91 (95% CI: 0.77, 4.77) and 1.18 (95% CI: 0.37, 3.77), respectively, compared with normal fetuses (the difference between these 2 risk ratios, P = 0.71). The authors conclude that neither the ultrasound-based nor the individualized reference does well in predicting adverse perinatal outcomes. The 5th percentile may be a better cutpoint than the 10th percentile in defining SGA.
Epidemiology Branch, the Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland 20892, USA. zhangj@mail.nih.gov
Jun
J
Zhang
Rafael
R
Mikolajczyk
Jaceteshwar
J
Grewal
Gila
G
Neta
Mark
M
Klebanoff
D000293:Adolescent; D000328:Adult; D001724:Birth Weight; D002986:Clinical Trials as Topic; D005260:Female; D047109:Fetal Development; D005317:Fetal Growth Retardation / Q000000981:diagnostic imaging* / Q000453:epidemiology; D005865:Gestational Age; D006801:Humans; D007231:Infant, Newborn; D007236:Infant, Small for Gestational Age; D054238:Perinatal Mortality; D011247:Pregnancy; D011295:Prenatal Care; D012016:Reference Values; D012107:Research Design; D018709:Statistics, Nonparametric; D016216:Ultrasonography, Prenatal; D014481:United States / Q000453:epidemiology
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