Water Immersion and Changes in the Fetoplacental Circulation

Pregnant women with pre-eclampsia and growth restricted fetuses often have a reduced function of the placenta. This is accompanied by an increased perinatal mortality and morbidity. By ultrasound it is possible to measure blood flow and vascular resistance in both the fetal umbilical cord and in the blood vessels supplying the uterus. A high resistance in these vessels occur before the child is severely affected. By immersion in water extracellular fluid is redistributed back into the circulation, and central blood volume increases. Previous studies have shown that maternal minute-volume increases, while blood pressure drops slightly. Also an increased amniotic fluid has been recorded. This has been interpreted as an expression of increased renal blood flow. Immersion into water could increase blood flow in the vessels supplying the uterus and thus increase blood flow to the child. The investigators aim to clarify this by examining blood flow and resistance in the blood vessel supplying the uterus and in the umbilical cord, while the participant is immersed into water. Initially, 25 healthy women with an uncomplicated singleton pregnancy recruited from the Department of Obstetrics and Gynaecology: Hvidovre University Hospital, Denmark, will be examined. The participant will act as its own control and measurements above water and immersed will be conducted at the same study session. Ultimately the investigators seek to contribute to a non-invasive option for prolonging those pregnancies where the fetus and/or maternal condition requires delivery several weeks before term, and where immersion of the pregnant woman in the water a few hours one to several times daily, may prolong the pregnancy the required number of hours/days for antenatal steroid treatment to be sufficient. There are no risks associated with the study and the project team considers it ethical to implement this. The study is not supported by pharmaceutical companies or other groups with economic i