Posture-related changes in sympathetic baroreflex sensitivity during normal pregnancy

AbstractNormal pregnancy is associated with vast adjustments in cardiovascular autonomic control. Sympathetic baroreflex sensitivity has been reported to be attenuated during pregnancy in animal models, but most studies in humans are cross-sectional and findings from longitudinal case studies are inconclusive. It remains unclear how sympathetic baroreflex sensitivity is altered longitudinally during pregnancy within an individual in different body postures. Therefore, this study examined the impact of posture on sympathetic baroreflex sensitivity in 24 normal-weight normotensive pregnant women. Spontaneous sympathetic baroreflex sensitivity was assessed during early (6 –11 weeks) and late (32–36 weeks) pregnancy and 6–10 weeks postpartum in the supine posture and graded head-up tilt (30° and 60°). In addition, data from the postpartum period were compared with (and no different to) 18 age-matched non-pregnant women to confirm that the postpartum period was reflective of a non-pregnant condition (online supplement). When compared with postpartum (−3.8 ± 0.4 bursts/100 heartbeats/mmHg), supine sympathetic baroreflex sensitivity was augmented during early pregnancy (−5.9 ± 0.4 bursts/100 heartbeats/mmHg,P <  0.001). However, sympathetic baroreflex sensitivity at 30° or 60° head-up tilt was not different between any phase of gestation (P >  0.05). When compared to supine, sympathetic baroreflex sensitivity at 60° head-up tilt was sign...
Source: Clinical Autonomic Research - Category: Research Source Type: research