The Effect of Maternal Supine Position on Umbilical and Cerebral Blood Flow Indices

Abstract

Maternal supine position in late gestation partially obstructs the aorta, due to the enlarged uterus, and leads to redistribution of blood flow, also impaired venous return due to compression of the inferior vena cava by the gravid uterus can also elicit supine hypotensive syndrome. Fetal brain sparing is a well-known phenomenon in obstetrics. It aims to maintain sufficient blood flow towards vital organ such as the brain, myocardium, and adrenals. This vascular adaptation takes place as the central nervous system is preferentially perfused, which is intended to maintain the highest degree of oxygen supply to the brain. This cross sectional study was carried out in maternity hospital Ain Shams University, feto-maternal unit, and 46 pregnant women participated with low risk pregnancy and no past history of any medical conditions, 15 of them are primegravid, all of them are between 36 and 40 weeks gestation. The mean maternal age was 25.9 + 6, the mean gestational age was 37.8 +4, the mean parity was 1 + 0.2, and the mean hemoglobin concentration was 11.7 + 1. For each woman, Doppler flow measurements were obtained from the UA (Resistance index, Pulsatility index and Systolic/diastolic ratio) and MCA (Resistance index, Pulsatility index and Peak systolic velocity) in the supine position. Subsequently, the women were asked to change into left lateral position for fifteen minutes, to allow feto-maternal adaptation to the new position, and Doppler measurements were then repeated.