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 ± 45.0 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.