Correlation between the duration of maternal rest in the left lateral decubitus position and the amniotic fluid volume increase.

OBJECTIVES: The purpose of this study was to show the relationship between amniotic fluid volume changes and the duration of maternal rest in the left lateral decubitus position.

METHODS: Pregnant women (n = 34) with an amniotic fluid index between 6 and 24 cm and an uncomplicated singleton pregnancy at 35 to 40 weeks' gestation were included in the study. After the initial amniotic fluid index measurements, the women were instructed to rest in the left lateral position, and the measurements were repeated at 15, 30, 45, 60, 75, and 90 minutes.

RESULTS: The amniotic fluid index increased at each sequential interval. Although each amniotic fluid index value was higher than the preceding one, only the 15- and 30-minute values were significantly higher than the preceding measurements (P < .001; P < .01, respectively). At the beginning of maternal rest in the left lateral position, 15 minutes of rest was sufficient to create significant changes (P < .001). However, after 30 minutes of rest, an additional 45 minutes was needed to create a significant amniotic fluid index increase (P < .01). The curve describing the amniotic fluid index increases caused by maternal rest resembled a saturation curve, and the maximum increase in the amniotic fluid volume was projected to be achieved approximately at the end of the second hour of the rest period.

CONCLUSIONS: The correlation between the duration of maternal rest and amniotic fluid volume changes is not linear. However, maternal rest in the left lateral decubitus position significantly increases the amniotic fluid volume, particularly in the first 30 minutes (maximum increase in the first 15 minutes).