Prenatal detection of fetal growth restriction in newborns classified as small for gestational age: correlates and risk of neonatal morbidity.

We examined the rate of detecting small for gestational age (SGA; birth weight < 10%) as intrauterine growth restriction (IUGR) prenatally at four centers and determined risks of composite neonatal morbidity (CNM) and mortality among detected versus undetected (no antenatal diagnosis of IUGR). A multicenter cohort study of 11,487 nonanomalous, singleton live births with sonographic exam before 22 weeks was performed. Of 11,487 births, 8% (n = 929) were SGA that met the inclusion criteria, with 25% of them being prenatally detected. The CNM among SGA births that were prenatally detected as IUGR was higher (23.3%) than undetected SGA (9.7%), but this difference was no longer significant following adjustments for confounding factors. Among preterm births (< 37 weeks), undetected SGA had significantly higher CNM (risk ratio [RR] 10.0, 95% confidence interval [CI] 6.3, 16.1) for deliveries at 24 to 33 weeks and RR 3.0, 95% CI 1.7, 5.4 for 34 to 36 weeks). In summary, only a quarter of SGA births were detected prenatally as IUGR and among preterm SGA, the CNM is significantly higher when SGA births are undetected as IUGR. Thieme Medical Publishers 333 Seventh Avenue, New York, NY 10001, USA.