Objective: The factors affecting cardiac output in normal pregnancy remain controversial. This study prospectively evaluates maternal central hemodynamics and cardiac structure and function by echocardiography, together with maternal stature correction and correlation of these variables in healthy pregnant women in the latter half of pregnancy.
Methods: One hundred sixty echocardiographic studies were performed in 35 healthy pregnant women for longitudinal evaluation from early second trimester until term and 6-12 weeks postpartum.
Results: Cardiac output increased significantly at the early to mid third trimester and was maintained until term. It increased predominantly in the latter half of pregnancy, and peak cardiac output of 46-51% occurred from a 15% increase in heart rate and 24% increase in stroke volume. Maternal cardiac output measured in the early third trimester showed a good correlation with maternal body surface area (r = 0.72; P <.001) and fetal birth weight (r = 0.52; P =.008). Left ventricular systolic function was preserved until term.
Conclusion: Maternal cardiac output peaks in the early to mid third trimester and is maintained until term. Significant correlations were observed among maternal cardiac output, maternal body surface area, and fetal birth weight.