Prenatal Application of the Individualized Fetal Growth Reference

摘要

The individualized reference for defining small for gestational age (SGA) at birth has gained popularity in recentnyears. However, its utility on fetal assessment has not been evaluated. The authors compare an individualized withnan ultrasound reference in predicting poor perinatal outcomes. Data from a large clinical trial in predominantly whitenUS women (1987–1991) with singleton pregnancies (n ¼ 9,526) were used. The individualized reference classifiednfewer SGA fetuses than the ultrasound reference, but the risks of adverse outcomes were similar between fetusesnclassified by both references. The risk increased substantially only when the percentiles fell below the 5th per-ncentile (likelihood ratio positive at birth ¼ 2.68 (95% confidence interval (CI): 2.00, 3.58) and 3.13 (95% CI: 2.34,n4.18) for ultrasound and individualized references, respectively). SGA fetuses defined by either the individualizednor ultrasound reference alone had risk ratios of adverse outcomes of 1.91 (95% CI: 0.77, 4.77) and 1.18 (95% CI:n0.37, 3.77), respectively, compared with normal fetuses (the difference between these 2 risk ratios, P ¼ 0.71). Thenauthors conclude that neither the ultrasound-based nor the individualized reference does well in predicting adversenperinatal outcomes. The 5th percentile may be a better cutpoint than the 10th percentile in defining SGA.