Arterial stiffness and fetal growth in normotensive pregnancy

Background Normal pregnancy is characterized by a decrease in peripheral resistance and generalized vasodilation resulting in plasma volume expansion, which is associated with intrauterine growth. Stiffness of the arterial system may be a measure of the degree of plasma volume expansion. Pulse wave velocity (PWV), measured by applanation tonometry, is a validated approach to determine arterial stiffness. Pulse pressure (PP) is considered a surrogate measure for arterial stiffness. The aim of this study was to evaluate the association between arterial stiffness and fetal growth. Methods In 50 normotensive pregnancies, carotid-femoral PWV was measured in the third trimester in 30° lateral position. Blood pressure measurements were performed with conventional auscultatory sphygmomanometry. Birth weight centiles and weight centiles at the age of 6 months were recorded. Linear regression models were used for statistical analyses. Results There was a significant relationship in PWV with both birth weight centiles and catch-up growth after birth, independent of mean arterial pressure (MAP). An increase of 1 m/sec in PWV was associated with a decrease in birth weight centiles by 17.6% and a catch-up of 22.3% in weight centiles after birth. A stronger association was found for pulse pressure and birth weight centiles. An increase of 1 mm Hg was associated with a decrease in birth weight centiles by 1.8%. There was no association between MAP and birth weight centiles. Conclusions In normotensive pregnancy arterial stiffness is associated with birth weight centile and catch-up growth after birth, independently from MAP. This suggests that arterial stiffness reflects maternal vascular adaptation to pregnancy better than blood pressure.