title: Fetal aortic diameter pulse wave response to changes in maternal position after membrane rupture.
abstract: An ultrasonic phase-locked echo-tracking system was used in order to study human fetal hemodynamics in relation to maternal postural changes after membrane rupture. Diameter pulse waves were recorded in the descending aorta of 17 fetuses presenting by the vertex in normal singleton pregnancies, with the mother in three different positions. The first measurements were made with the mother in the slightly left lateral recumbent (horizontal), then upon transition to the upright (70 degrees), and finally upon return to the horizontal. Change from the horizontal to the upright position produced a moderate but significant increase (p < 0.05) in maternal heart rate, while the systolic and diastolic blood pressures remained unchanged. No significant changes were seen in the fetal pulse wave variables (i.e. end-diastolic diameter, relative pulse amplitude, maximum incremental velocity, late decremental velocity, pulse duration, relative crest time and pulse wave velocity). The absence of fetal hemodynamic changes possibly reflects the presence of a protective effect against I gravitational stress to the fetal cardiovascular system provided by the remaining volume of amniotic fluid and the abundant fetal extracellular water.
authors.affiliation: Department of Obstetrics and Gynecology, University of Lund, Malmö General Hospital, Sweden.
authors.forename: H
authors.initials: H
authors.lastname: Stale
authors.forename: G
authors.initials: G
authors.lastname: Gennser