Neurovascular coupling in pregnancy and the risk of preeclampsia.

BACKGROUND AND PURPOSE: This study investigated whether a short testing of neurovascular coupling during midterm pregnancy could identify women at risk for subsequent preeclampsia. METHODS: Transcranial Doppler sonography of the posterior cerebral artery during a brief visual stimulation was analyzed in 68 women at midterm pregnancy, the primary clinical end point was preeclampsia. RESULTS: Women with bilateral notching of the uterine arteries showed an exaggerated visually evoked blood flow increase and longer time-to-peak. Neurovascular coupling was not significantly associated with the occurrence of preeclampsia. CONCLUSIONS: Neurovascular coupling was altered in women with impaired uteroplacentar vasoregulation but not a significant predictor of preeclampsia.

Dynamic cerebral autoregulation in pregnancy and the risk of preeclampsia.

Preeclampsia may affect severely the cerebral circulation leading to impairment of cerebral autoregulation, edema, and ischemia. It is not known whether impaired autoregulation occurs before the clinical onset of preeclampsia, and whether this can predict the occurrence of preeclampsia. Seventy-two women at 25 to 28 weeks of gestation were studied. Control values were derived from 26 nonpregnant women. Dynamic properties of cerebral autoregulation (DCA) were measured in the middle and posterior cerebral artery using transcranial Doppler and transfer function analysis (phase and gain) of respiratory-induced 0.1 Hz hemodynamic oscillations. Uterine artery ultrasound was performed to search for a notch sign as an early marker of general endothelial dysfunction. All women were followed up until 6 weeks after delivery for the occurrence of preeclampsia. The autoregulation parameter gain did not differ between pregnant and nonpregnant women. Phase was slightly but significantly higher in pregnant women, indicating better DCA. Women with a notch sign did not show altered DCA. A history of preeclampsia during a previous pregnancy was associated with lower phase in middle cerebral artery and posterior cerebral artery (P<0.05 each). During follow-up, 9 women developed preeclampsia. None of the DCA parameters were associated with the occurrence of preeclampsia. In conclusion, DCA is well preserved during late midterm pregnancy, even in women with disturbed uterine blood flow. Yet, pregnant women with preeclampsia in a previous pregnancy seem to have poorer DCA. Although limited in statistical power, this study does not support DCA as a strong early risk marker of preeclampsia.