The maternal venous system: the ugly duckling of obstetrics

In pregnancy, both maternal vascular tone and cardiac function are considered key players to reach a normal outcome for both mother and child. This complex story of maternal hemodynamics is intensely discussed in current scientific literature, however the role of the maternal veins has been strongly underestimated. We developed and evaluated a set of measurable objective parameters which give an indication of venous function, i.e. the venous impedance index and the venous pulse transit time. These parameters turned out to be subject to changes throughout normal pregnancy and in preeclampsia enabling their use in gestational hemodynamic -studies. From our studies, we concluded that the venous system is a crucial determinant of cardiac output, which can be estimated by impedance cardiography. The introduction of these non-invasive techniques in obstetrics enables profiling the maternal cardiovascular system, integrating both arteries and veins, as well as maternal cardiac -function. Studying the cascade of cardiovascular changes throughout pregnancy using such non-invasive, easily applicable, and highly accessible methods opens perspectives to introduce this maternal cardiovascular profile in several -clinical settings. The early discrimination between low and high risk patients, together with the classification of different pregnancy disorders may help guiding the clinical work-up of the pregnant population regarding both prevention and treatment, as well as follow-up. We illustrate that the venous system, being an "ugly duckling" at first neglected by the medical world, transforms and matures into a beautiful swan, accepted by the obstetric world. We are confident that this is the beginning of many other studies regarding the maternal venous system, an important piece of the gestational physiology puzzle.