Association between Adverse Outcomes and Middle Cerebral Artery Pulsatility Index Change Based on Maternal Position Change

We have previously demonstrated that maternal position changes directly affect the fetal middle cerebral artery (MCA) Doppler pulsatility indices (PI) and may serve as a predictor for adverse pregnancy outcomes. We sought to confirm whether changes in fetal MCA Doppler PI due to position changes are associated with adverse outcomes.We conducted a prospective cohort study of pregnant people with a singleton, nonanomalous fetus, recruited between 18 and 24 weeks of gestation, in a single tertiary care center from December 2021 to February 2022. MCA Dopplers were obtained, and PI indices were measured and recorded, first in the supine position and then in the maternal left lateral (LL) position. The primary outcome was a composite of adverse outcomes (preeclampsia, fetal growth restriction, and oligohydramnios). Based on our prior findings suggesting that a PI Δ of 0.22 may serve as a dividing threshold between low- high-risk pregnancies, we divided the cohort into those above and below Δ = 0.22. Demographics were compared using univariable analyses. Multivariable logistic regression was performed comparing the composite and individual pregnancy outcomes controlling for statistically significant variables.We recruited 228 patients and followed them to delivery. There were 107 that had a PI Δ < 0.22 and 121 that had a PI Δ ≥0.22. The primary outcome of composite adverse outcomes did not differ between the groups (adjusted odd ratio [aOR]: 0.53; 95% confidence interval [CI]: 0.26-1.08). However, pregnancies with PI Δ ≥0.22 were more likely to develop preeclampsia than pregnancies with PI Δ < 0.22 (aOR: 3.30; 95% CI: 1.02-10.69).The primary outcome of composite adverse outcomes did not differ between the groups. However, we did find that a second trimester fetal MCA PI Δ ≥0.22 with maternal position changes at anatomy ultrasound was associated with developing preeclampsia. This data suggests that there may be an association between early decreased fetoplacental reserve and the development of preeclampsia. · Second trimester MCA PI Δ ≥0.22 with maternal position changes was associated with preeclampsia.. · There may be a link between decreased fetoplacental reserve and developing preeclampsia.. · Aside from preeclampsia there were no differences in adverse outcomes between the two groups..