Prediction of small-for-gestational-age neonates: screening by uterine artery Doppler and mean arterial pressure at 30-34 weeks

Abstract

Objective: To investigate the potential value of uterine artery (UtA) pulsatility index (PI) and mean arterial pressure (MAP) at 30-34 weeks' gestation in the prediction of small-for-gestational-age (SGA) neonates, in the absence of pre-eclampsia (PE).

Methods: This was a screening study in singleton pregnancies at 30-34 weeks' gestation, including 1727 that delivered SGA neonates with a birth weight < 5(th) percentile and 29 122 that were unaffected by SGA, PE or gestational hypertension (normal group). Multivariable logistic regression analysis was used to determine if measuring the UtA-PI and MAP improved the prediction of SGA neonates provided by screening with maternal characteristics and medical history (maternal factors), and estimated fetal weight (EFW) calculated from fetal head circumference, abdominal circumference and femur length.

Results: Combined screening by maternal factors and EFW Z-scores predicted 79%, 87% and 92% of SGA neonates delivering < 5 weeks following assessment, with a birth weight < 10(th) , < 5(th) and < 3(rd) percentiles, respectively, at a false-positive rate of 10%. The addition of UtA-PI and MAP improved the respective detection rates to 83%, 91% and 93%. Screening by maternal factors and EFW Z-scores predicted 53%, 58% and 61% of SGA delivering ≥ 5 weeks following assessment and these rates increased to 53%, 60% and 63% with the addition of UtA-PI and MAP.

Conclusion: Combined testing by maternal factors, fetal biometry, UtA-PI and MAP at 30-34 weeks' gestation could identify a high proportion of pregnancies that deliver SGA neonates.

Keywords: mean arterial pressure; pre-eclampsia; pyramid of antenatal care; small-for-gestational age; third-trimester screening; uterine artery Doppler.