First-trimester uterine artery Doppler indices in the prediction of small-for-gestational age pregnancy and intrauterine growth restriction.

OBJECTIVES

To assess the relationship of first-trimester uterine artery Doppler indices with subsequent delivery of small-for-gestational age (SGA) neonates or intrauterine growth restriction (IUGR).

METHODS

This was a prospective study in which uterine artery Doppler assessment was performed at 11-14 weeks in 3010 women with singleton pregnancies. Resistance indices (RI) and incidence of bilateral notching were compared between women with normal pregnancies (n = 2445) and those who delivered: SGA neonates (birth weight < 10th centile) (n = 377); SGA neonates who had been affected by pre-eclampsia (n = 27); IUGR neonates (birth weight < 10th centile and abnormal Doppler indices) with delivery > or = 37 weeks (n = 62); and IUGR neonates requiring preterm delivery (delivery < 37 weeks) (n = 36).

RESULTS

The first-trimester uterine artery mean RI and prevalence of bilateral notching were significantly higher in women destined to deliver SGA neonates than in women with normal pregnancies (median uterine artery RI, 0.74 vs. 0.70, P < 0.001; prevalence of bilateral notches, 56% vs. 43%, P < 0.001). The areas under the receiver-operating characteristics curves for the prediction of SGA without pre-eclampsia, IUGR, preterm IUGR and SGA with pre-eclampsia were 0.602, 0.687, 0.776 and 0.708, respectively. There was a statistically significant inverse relationship between mean uterine artery RI and gestational age at delivery in the SGA pregnancies without pre-eclampsia (R = - 0.329, P = 0.01).

CONCLUSIONS

There is a significant relationship between first-trimester uterine artery Doppler RI and the subsequent development of SGA. The sensitivity of first-trimester uterine artery Doppler is greater for SGA with pre-eclampsia than it is for IUGR alone. This could be because these two entities may have different underlying placental abnormalities that are detected variably on first-trimester uterine artery Doppler evaluation.