Cerebrovascular function in women with a history of hypertensive complications of pregnancy

Abstract

Background and Objective: Cerebrovascular function is fundamental to maintaining global brain health, supporting processes including cognition, emotion, memory, attention, and perception. Tight regulation of cerebral blood flow (CBF) is achieved through several intrinsic mechanisms, among which arterial carbon dioxide (PaCO₂) is the most potent modulator, particularly at the level of the cerebral microvasculature. Cerebrovascular reactivity (CVR) to CO₂ is widely used to assess vascular function; however, its characterization in certain high-risk populations remains limited. Preeclampsia (PE), a hypertensive disorder of pregnancy marked by systemic endothelial and microvascular dysfunction, is associated with increased long-term risk of cerebrovascular disease and cognitive decline. While impairments in cerebral macrovascular function have been reported in women with a history of PE, microvascular CVR remains incompletely understood in this population. Therefore, we aimed to determine whether women with a history of preeclampsia exhibit impaired cerebral microvascular reactivity compared to women with a history of uncomplicated pregnancy. Methods: Women with a history of PE (n = 9) and normotensive pregnancy history controls (CON; n = 11), an average of 8 (range 2–24) years postpartum, were studied. Cerebral microvascular hemodynamics were assessed using near-infrared spectroscopy (NIRS) during repeated 30-second breath-hold maneuvers to induce hypercapnia. CVR was quantified as the change in total hemoglobin (THb) relative to changes in end-tidal CO₂ (EtCO₂, %). Cerebrovascular conductance index (CVCi) was calculated to account for changes in mean arterial pressure (MAP). As part of an exploratory analysis, a subset of participants performed a Valsalva Maneuver with measurement of middle cerebral artery velocity using transcranial doppler ultrasound to assess cerebral autoregulation (CAiI-II; CAiIII-IV) and indices of autonomic function. Results: Baseline characteristics, including MAP, EtCO₂, and THb, were not different between groups (p > 0.05). Microvascular CVR did not differ between PE and CON (p = 0.389), and no group differences were observed in CVCi (p = 0.724). Exploratory analyses revealed no differences in cerebral autoregulatory indices or autonomic function (p > 0.05); however, cardiometabolic health - reflected by BMI and CVD risk factor burden - was significantly associated with CVR (BMI p = 0.046; CVD risk factor burden p = 0.007). Conclusions: Contrary to our hypothesis, CVR to CO₂ is unaltered compared to controls in women several years following preeclamptic pregnancy. These findings suggest that PE alone may not result in persistent cerebrovascular dysfunction. This highlights the potential importance of cardiometabolic health and lifestyle factors compounded with aging and pregnancy history in shaping long-term cerebrovascular risk. Longitudinal studies are warranted to further define the trajectory of cerebrovascular function following PE and further elucidate the impact of postpartum cardiometabolic and lifestyle influences.