Ophthalmic artery doppler and biomarkers of impaired placentation at 36 weeks’ gestation in pregnancies with small fetuses

Abstract

ABSTRACTObjectivesFirst, to compare the ophthalmic artery peak systolic velocity (PSV) ratio and biomarkers of impaired placentation at 36 weeks’ gestation in women who delivered small for gestational age (SGA) or fetal growth restricted (FGR) neonates in the absence of hypertensive disorders with those who developed preeclampsia (PE) or gestational hypertension (GH) and those unaffected by SGA, FGR, PE or GH. Second, to examine the associations between PSV ratio, uterine artery pulsatility index (UtA‐PI), placental growth factor (PlGF) and soluble fms‐like tyrosine kinase‐1 (sFLT‐1) with birthweight z‐score or percentile.MethodsThis was a prospective observational study in women attending for a routine hospital visit at 35+0 ‐ 36+6 weeks’ gestation This visit included recording of maternal demographic characteristics and medical history, ultrasound examination for fetal anatomy and growth, and measurement of maternal ophthalmic artery PSV ratio, UtA‐PI, PlGF and sFLT‐1. The values of PSV ratio, UtA‐PI, PlGF and sFLT‐1 were converted to multiples of the median (MoM) or deltas and the median MoMs or deltas of these biomarkers in the SGA, FGR, PE and GH groups were compared to those in the unaffected group. Regression analysis was used to examine the relationship of PSV ratio delta, UtA‐PI MoM, PlGF MoM and sFLT‐1 MoM with birthweight z‐score after exclusion of PE and GH.ResultsThe study population of 9033 pregnancies contained 7696 (85.2%) that were unaffected by FGR, SGA, PE or GH, 182 (2.0%) complicated by FGR in the absence of PE or GH, 698 (7.7%) with SGA in the absence of FGR, PE or GH, 236 (2.6%) with PE and 221 (2.4%) with GH. Compared to unaffected pregnancies, in both the FGR and SGA groups the PSV ratio delta, and sFLT‐1 MoM were increased and PlGF MoM was decreased; UtA‐PI MoM was increased in the FGR, but not the SGA group. The magnitude of changes in biomarkers in the FGR and SGA groups was smaller than in PE and GH. In the non‐hypertensive pregnancies there were significant inverse associations between PSV ratio delta and UtA‐PI MoM with birthweight z‐score so that the values were increased in small babies and decreased in large babies. There was a quadratic relationship between PlGF MoM and birthweight z‐score, with low levels in small babies and high levels in large babies. There was no significant association between sFLT‐1 MoM and birthweight z‐score.ConclusionOphthalmic artery PSV ratio, reflective of peripheral vascular resistance, and UtA‐PI, PlGF and sFLT‐1, biomarkers of impaired placentation, are altered in pregnancies complicated by hypertensive disorders and to a lesser extent in non‐hypertensive pregnancies delivering SGA and FGR neonates. The linear association between each biomarker and birthweight z‐score suggests the presence of a continuous physiological relation between fetal size and peripheral vascular resistance and placentation, rather than a dichotomous relation of high peripheral resistance and impaired placentation in small by comparison with non‐small fetuses.This article is protected by copyright. All rights reserved.