Effects of maternal prone position on the umbilical arterial flow

Objective. The objective of our study was to clarify the effect of the mate rnal prone position on the fete-placental flow. In this position, the uteri ne compression of the large maternal vessels was expected to be completely eliminated. Methods. Twenty-three normal pregnant women were cross-sectionally examined in the supine, the left lateral, the right lateral and the prone position. The systolic/diastolic ratios for the umbilical artery were calculated for each position. Results. The umbilical arterial systolic/diastolic ratio in the prone posit ion significantly decreased compared with that in the supine position. The left and right lateral position showed no significant change in the systoli c/diastolic ratio. Conclusion. The maternal prone position can provide complete relief of uter ine compression of the large maternal vessels.