609: Does the NICHD growth velocity percentile predict morbidity in fetuses with suspected growth restriction?

Abstract

To utilize a novel tool developed by the NICHD to assess its ability to identify pathologic growth restriction by calculating growth velocity and percentiles in a series of singleton fetuses that were growth restricted at delivery. This was a retrospective review of 196 singleton pregnancies delivered from 2012-2015 that were growth restricted at delivery, defined as estimated fetal weight at less than 10%ile for gestational age based on the formulas of Hadlock et al. Information collected included demographics, neonatal outcomes, and sonographic estimated fetal weight measurements. The data were then inputted into the growth velocity percentile calculator and the resultant percentile was recorded. The neonatal composite morbidity outcome was defined as hyperbilirubinemia, hypoglycemia, need for supplemental oxygen, hypothermia, or NICU admission. Growth velocity was measured as the change in estimated fetal weight (grams) from anatomy ultrasound (18-22 wga) to the mid-third trimester (30 wga or later; time period recorded in weeks). SGA was defined as birthweight less than 10%ile for gestational age. If the anatomy ultrasound wasn’t performed until the third trimester, growth velocity was measured from the earliest to the next growth ultrasound after 30 wga. All patients delivered at 37-39 wga. The data were normally distributed. The average birthweight was 2854g. Mean velocity was 72.6 g/wk and percentile was 22.5. Growth velocity did not predict birthweight. There was no association between the velocity percentile and the composite neonatal outcome. There was no statistically significant difference in the occurrence of the composite outcome or in the percentage of fetuses classified as SGA with velocity percentile less than and above 10. In our cohort, growth velocity measured from the time point of the anatomy ultrasound to the mid-third trimester was not predictive of the composite neonatal morbidity or SGA. The addition of data from the NICHD growth velocity calculator did not reveal any significant result. Further studies are needed to explore this novel tool.