Adverse perinatal outcomes are strongly associated with degree of abnormality in uterine artery Doppler pulsatility index

Abstract

ObjectivesTo investigate the association between varying degrees of abnormality in the uterine artery Doppler pulsatility index (UtA‐PI) and adverse perinatal outcomes.MethodsProspective study of 33,364 women who gave birth to singleton, non‐anomalous babies in Oxford, following universal measurement of UtA‐PI in mid‐pregnancy. Relative risk ratios for the primary outcomes of extended perinatal mortality and live birth with severe small‐for‐gestational‐age (SGA) were calculated by multinomial logistic regression, for early preterm birth (<34+0) and late preterm/term birth (≥34+0). The risks were also investigated for iatrogenic preterm birth or a composite adverse outcome before 34+0 weeks.ResultsCompared with women with normal UtA‐PI, the risk of extended perinatal mortality before 34+0 weeks was higher in women with UtA‐PI >90th centile (RRR 4.7, 95% CI 2.7‐8.0, p<0.001), but this was not demonstrated in later births. The risk of severe SGA birth was strongly associated with abnormal UtA‐PI for both early births (RRR 26.0, 95% CI 11.6‐58.2, p<0.001), and later births (RRR 2.3, 95% CI 1.8‐2.9, p<0.001). Women with a raised UtA‐PI were more likely to undergo early iatrogenic birth (RRR 7.8, 95% CI 5.5‐11.2, p<0.001). For each of the outcomes and the composite outcome, the risk increased significantly in association with the degree of abnormality, through the 90th, 90‐94th, 95‐99th and >99th centiles (ptrend<0.001).ConclusionsAn elevated UtA‐PI is a key predictor of iatrogenic preterm birth, severe SGA and perinatal loss up to 34+0 weeks. It is the 90th centile that should be used, and management should be further tailored to the degree of abnormality, as pregnancies with very raised UtA‐PI measurements constitute a group at extreme risk.This article is protected by copyright. All rights reserved.