Maternal Wave Reflections and Arterial Stiffness in Normal Pregnancy as Assessed by Applanation Tonometry

Abstract

Normal pregnancy is associated with profound alterations in the maternal cardiovascular system. The aim of the present study was to assess noninvasively, using applanation tonometry, the maternal central aortic blood pressures (BP), effects of wave reflection and arterial stiffness (aortic and brachial pulse wave velocity) in normal pregnancy. This was a cross sectional study including 193 women with normal singleton pregnancies at 11 to 41 weeks of gestation and 23 nonpregnant controls, matched for age and height. Compared to nonpregnant controls, pregnant women had lower mean arterial pressure (85+/-8.9 mm Hg versus 81.1+/-7.2 mm Hg; P=0.01), central systolic BP (103+/-11 mm Hg versus 96+/-8 mm Hg, P=0.001), central diastolic BP (71+/-9 mm Hg versus 67+/-7 mm Hg, P=0.008), and augmentation index (AIx) (19+/-11% versus 4+/-12%, P<0.001). The AIx changed significantly with gestation reaching its nadir at midpregnancy (R(2)=0.05, P=0.007). This change was present even after adjusting for maternal age (P<0.001), heart rate (P<0.001), and mean arterial BP (P<0.001); known determinants of AIx. The pulse wave velocity (carotid-radial and carotid-femoral) did not change significantly with gestation and was marginally different between pregnant and nonpregnant women (P=0.03 and P=0.05 for carotid-radial and carotid-femoral respectively). However, adjustments for maternal age and mean arterial pressure rendered these differences nonsignificant (P=0.2 for carotid-radial, P=0.5 for carotid-femoral). In summary, we found that normal pregnancy is associated with a reduction in central BP and wave reflection.