The relationship of maternal position to the results of brief nonstress tests: A randomized clinical trial

Objective: This study was undertaken to determine whether maternal posture (left lateral recumbent vs semi-Fowler position) had any effect on nonstress test results when the test was performed for a shortened period (10 minutes). Study Design: In this randomized clinical trial of 108 patients with singleton pregnancies at 32 to 42 weeks’ gestation, patients were randomly assigned to a “sitting first” (semi-Fowler position) or a “supine first” (left lateral recumbent position) group at the initial visit. The order of position was alternated at subsequent visits. Ten minutes of fetal heart rate monitoring was performed in each position at each visit. Computer analysis of the nonstress test was used to interpret each 10-minute segment for reactivity. Statistical analyses were performed on the paired nonstress test unit (sitting and supine). Results: There were no adverse clinical outcomes among the participants. Logistic regression analysis showed that both the sequence of the nonstress test and the position were significant and independent factors related to nonstress test reactivity. Tests performed during the second 10 minutes and tests performed with the patient in the semi-Fowler position were more likely to have reactive results. Conclusion: The semi-Fowler position is a superior position for conductinng a nonstress test in a shor period. Use of this position could decrease the need for prolonged monitoring, thus leading to a more time-effective evaluation of patients at risk. (Am J Obstet Gynecol 2000;182:1070-2.)