Sympathetic neurovascular regulation during pregnancy: A longitudinal case series study

Abstract

The adaptations of sympathetic nerve activity (SNA) during pregnancy remain poorly understood. An increase in blood volume, cardiac output (Q) and SNA with a concomitant drop in total peripheral resistance (TPR), suggest that during pregnancy there is a reduced transduction of SNA into TPR. Most of these findings have originated from cross-sectional studies, thus, we conducted a longitudinal assessment of SNA and TPR in two participants. Measures were made pre-pregnancy (early follicular phase), four occasions during pregnancy, and at two-months postpartum. Mean arterial pressure (MAP) and Q were used to calculate TPR. SNA was measured using microneurography (peroneal nerve). There was a gestational-dependent increase in SNA burst frequency (r² = 0.96, P = 0.009). Neurovascular transduction, however, decreased 53% in both women. Sympathetic hyperactivity was reversed in the postpartum whereas neurovascular transduction remained lower. These longitudinal data highlight the progressive sympathoexcitation of pregnancy, which is offset by a concurrent reduction in neurovascular transduction.

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