49. Adaptation of cardiac output and systemic vascular resistance during pregnancy: Systematic review and meta-analysis

Abstract

Introduction Insights in the adaptation of cardiac output (CO) and peripheral systemic vascular resistance in normal pregnancy may aid in identifying women with deviant adaptation. These women are thought to be at risk for hypertensive related complications during pregnancy. Objectives First, to describe the pattern of CO and peripheral resistance changes in normotensive singleton pregnancies. Second, to explore the adaptation of these variables in pregnancies complicated by hypertension, pre-eclampsia and/or foetal growth restriction. Methods We performed a meta-analysis of systematically reviewed literature on CO and peripheral resistance throughout normotensive and complicated pregnancies, using PubMed (NCBI) and Embase (Ovid) databases. Only studies reporting measurements during pregnancy and non-pregnant reference values were included. Pooled mean differences between pregnant and non-pregnant women were calculated for predefined intervals of gestational age using a random-effects model. Results In total, 92 studies were included in this meta-analysis. In uncomplicated pregnancies, CO progressively increased from the first weeks on. After peaking in the early third trimester (+1.47 L/min, over 30% increase as compared to the non-pregnant reference group), CO declined slightly until term. Next to that, peripheral resistance decreased progressively until early third trimester (−316 dyn · s · cm−5, −24% as compared to the non-pregnant group), after which it increased a little. In the first trimester of complicated pregnancies, an augmented increase in CO was observed (+1.36 L/min versus +0.73 L/min in the uncomplicated pregnancies, p Discussion During normal pregnancy, CO increases and peripheral resistance decreases by 30% and 24% respectively, reaching their maximum measure in the second half of pregnancy. Deviant hemodynamic adaptations showing an initial augmented increase with a cross-over to a low cardiac output might identify pregnancies that will be complicated by hypertension and/or growth restriction.