Assessment of uterine activity in ambulatory patients at high risk of preterm labor and delivery.

With use of an ambulatory tocodynamometer, prelabor uterine activity was recorded daily during pregnancy in 34 patients at increased risk of preterm labor and delivery. The data indicate that the frequency of contractions was significantly greater among women who subsequently developed preterm labor when compared to that observed among women who labored at term. This difference was present up to several weeks before the onset of labor. An additional significant rise in frequency of contractions could be observed within the last 24 hours before the development of clinically apparent preterm labor, as evidenced by progressive cervical dilation and effacement. If these results can be reproduced in a larger sample, intermittent ambulatory monitoring may offer an effective way to better identify patients at risk of preterm labor as well as enhance the early diagnosis of this event.