Effects of the Maternal Position and Rest on the Fetal Urine Production Rate A Prospective Study Conducted by 3-Dimensional Sonography Using the Rotational Technique (Virtual Organ Computer-Aided Analysis)

Objectives-The purpose of this study was to determine the effect of the maternal left lateral decubitus position and rest on the fetal urine production rate. Methods-Fifty-four pregnant women with a normal amniotic fluid volume who had a singleton pregnancy between 26 and 40 weeks' gestation were included in this prospective study. Exclusion criteria included rupture of membranes, intake of any food or liquid within the previous 4 hours, and maternal or fetal complications. The amniotic fluid index was determined by averaging 2 or 3 repetitive measurements of the 4 amniotic fluid quadrants at the time of fetal urinary bladder volume measurements. The fetal urine production rate was measured using virtual organ computer-aided analysis. The amniotic fluid index and fetal urine production rate before and after the left lateral position rest period were compared by a paired Student t test. The Pearson correlation was used to study the relationships among the maternal age, gestational age, test time, amniotic fluid index, and fetal urine production changes. Results-The mean amniotic fluid indices +/- SD before and after the rest period were 151.0 4 +/- 5.0 and 172.5 +/- 46.7 mm, respectively, indicating a significant increase in the amniotic fluid index (P < .05). The mean fetal urine production rates before and after the rest period were 73.7 +/- 66.8 and 151.8 +/- 119.9 mL/h, respectively, indicating a significant increase in fetal urine production (P < .05). Conclusions-The fetal urine production rate and amniotic fluid index are markedly increased by maternal rest in the left lateral decubitus position.