Pregnancy induces persistent changes in vascular compliance in primiparous women

Abstract

Objective Pregnancy induces rapid, progressive and substantial changes to the cardiovascular system. The low recurrence risk of preeclampsia, despite familial predisposition, suggests an adaptation associated with pregnancy that attenuates risk for subsequent preeclampsia. We aimed to evaluate the persistent effect of pregnancy on maternal cardiovascular physiology. Study Design Forty-five healthy nulliparous women underwent baseline cardiovascular assessment preconception and repeated an average of 30 months later. After baseline evaluation, 17 women (Preg) conceived singleton pregnancies and all delivered at term. The remaining 28 women comprised the non-pregnant control group (NP). We measured mean arterial blood pressure (MAP), cardiac output (CO), plasma volume (PV), pulse wave velocity (PWV), uterine blood flow (UBF), and flow-mediated vasodilation (FMD) at each visit. Results There was a significant decrease in mean arterial pressure from the prepregnancy visit to postpartum in women with an interval pregnancy (prepregnancy: 85.3±1.8, postpartum: 80.5±1.8 mm Hg), with no change in NP subjects (visit 1: 80.3±1.4, visit 2: 82.8±1.4 mm Hg), (p = .002). Pulse wave velocity was significantly decreased in women with an interval pregnancy (prepregnancy: 2.73±0.05, postpartum: 2.49±0.05 m/s), as compared to those without an interval pregnancy (visit 1: 2.56±0.04, visit 2: 2.50±0.04 m/s), (p = .005). We did not observe a residual effect of pregnancy on cardiac output, plasma volume, uterine blood flow or flow-mediated vasodilation. Conclusion Our observations of decreased mean arterial pressure and reduced arterial stiffness following pregnancy suggest a significant favorable effect of pregnancy on maternal cardiovascular remodeling. These findings may represent a mechanism by which preeclampsia risk is reduced in subsequent pregnancies.

Cardiac output and related haemodynamics during pregnancy: a series of meta-analyses

“…Within the extended postpartum period,  increases modestly above non-pregnant values 11. Previous studies have reported prolonged effects on cardiovascular function following gestation, including increased arterial compliance 42. In the late postpartum, SVR is reduced below non-pregnant and early postpartum levels.…”

Exercise and pregnancy in recreational and elite athletes: 2016 evidence summary from the IOC expert group meeting, Lausanne. Part 1—exercise in women planning pregnancy and those who are pregnant

“…From about the fifth week of gestation, pregnancy induces rapid, progressive and substantial alterations to the cardiovascular system,51 which ensure blood supply to the fetus 52. Oestrogen-mediated remodelling reduces vascular tone, leading to a primary reduction in afterload and an increase in venous capacitance 51.…”

Impact of Immune Deficiency on Remodeling of Maternal Resistance Vasculature 4 Weeks Postpartum in Mice

“…2,3 Both systemic and uterine vascular resistances are decreased, 4,5 due to vasodilation in mesenteric 6 and uterine circulations, [6][7][8] and this enhances blood flow to the uterus. In addition, pregnancy induces changes in structural parameters such as distensibility in the uterine vessels 5 and stiffness in the systemic vasculature, [9][10][11] among other important modifications of vascular response.…”

“…However, some degree of pregnancy-induced vascular adaptation continues PP 9,12-14 and includes increased cardiac output, decreased peripheral vascular resistance, 13 and changes in vascular compliance 9 and is regulated by molecules such as nitric oxide (NO) 15 and by changes in cardiac structure and function. 16,17 Moreover, PP systemic vasculature may exhibit new remodeling, such as outward remodeling of mesenteric resistance arteries, 12 which may result in the redistribution of the cardiac output systemically as blood flow to the uterus decreases to approximate the prepregnancy condition.…”