Uterine and fetal placental Doppler indices are associated with maternal cardiovascular function

Background and Objectives The mechanism underlying fetal-placental Doppler changes in pre-eclampsia and/or fetal growth restriction are unknown though both are associated with maternal cardiovascular dysfunction. We sought to investigate whether there was a relationship between maternal cardiac output and vascular resistance and feto-placental Doppler in healthy and complicated pregnancy. Study Design Women with healthy (n= 62), PE (Pre eclampsia) (n=13), PE+FGR (Pre eclampsia with fetal growth restriction) (n=15) or FGR (Fetal growth restriction) (n=17) pregnancies from 24-40 weeks were included. All underwent measurement of cardiac output (CO) using an inert gas rebreathing technique, and derivation of peripheral vascular resistance (PVR). Uterine and fetal Doppler indices were recorded: the latter were z-scored to account for gestation. Associations were determined by polynomial regression analyses. Results Mean uterine artery pulsatility index (PI) was higher in FGR (Fetal growth restriction) (1.37, p=0.026) and PE+FGR (Pre eclampsia with fetal growth restriction) (1.63, p=0.001) but not PE (Pre eclampsia) (0.92, p=1) compared to controls (0.8). There was a negative relationship between uterine PI and CO (r2=0.101; p=0.025) and umbilical PI z-score and CO (r2=0.078; p=0.015), and positive associations between uterine PI and PVR (r2=0.150; p=0.003) and umbilical PI z-score and PVR (r2= 0.145; p=0.001). There was no significant relationship between CO and PVR with cerebral Doppler. Conclusions Uterine artery Doppler is abnormally elevated in FGR with and without PE, but not in PE: this may explain the limited sensitivity of uterine artery Doppler for all these complications considered in aggregate. Furthermore, impedance within feto-placental arterial vessels is at least in part associated with maternal cardiovascular function. This relationship may have important implications for fetal surveillance and would inform therapeutic options in those pathological pregnancy conditions currently-and perhaps erroneously- attributed purely to placental mal-development. Uterine and fetal placental Doppler indices are significantly associated with maternal cardiovascular function. The classical description of uterine and fetal Doppler changes being initiated by placental maldevelopment is a less plausible explanation for the pathogenesis of the conditions than that relating to maternal cardiovascular changes.JT is funded by Imperial College NHS Trust with support from the Imperial Healthcare Charities. CCL and PB are supported by the UK National Institute for Health Research Biomedical Research Centre (BRC) based at Imperial College Healthcare National Health Service Trust and Imperial College London. CMM is funded, in part by the NIHR Cambridge BRC