Abstract

OBJECTIVE: To examine the association of uterine artery (UtA) Doppler indices and cerebroplacental ratio (CPR) on perinatal outcome at term. METHODS: This retrospective cohort study conducted in a single tertiary referral centre included all singleton pregnancies undergoing ultrasound assessment in the third trimester, which subsequently delivered at term. Fetal biometry and Dopplers including the umbilical artery (UA), middle cerebral artery (MCA) and uterine artery were recorded. Data was corrected for gestational age and CPR was calculated as a ratio between the MCA pulsatility index (PI) and UA PI. Logistic regression analysis was conducted to examine for independent predictors of adverse perinatal outcome. RESULTS: The study included 7013 pregnancies; 12 were complicated by perinatal death. When compared to pregnancies resulting in live birth, pregnancies complicated by perinatal death had significantly more small for gestational age (SGA) infants (27.3% vs 5%, p = 0.001) and a higher incidence of low CPR (16.7% vs 4.5%, p = 0.041). A subgroup analysis comparing 1527 low risk pregnancies demonstrated that the UtA PI MoM, CPR <5(th) centile and estimated fetal weight (EFW) centile were all significantly associated with the risk of perinatal death at term (all p < 0.05). After adjusting for confounding variables, only EFW (OR 0.96, 95% CI 0.93-0.99; p = 0.003) and UtA PI MoM (OR 13.10, 95%CI 1.95-87.89; p = 0.008) remained independent predictors of perinatal death in the low risk cohort. CONCLUSION: High uterine artery PI at term is independently associated with increased risk of adverse perinatal outcome regardless of fetal size. These results suggest that perinatal mortality at term is related, not only to EFW and fetal redistribution (CPR), but also to indices of uterine perfusion.