Detection of preterm labor by ambulatory monitoring of uterine activity: a preliminary report.

Effective tocolytic therapy depends on the ability to make an early diagnosis of preterm labor. This study was designed to assess whether daily ambulatory home monitoring of uterine activity could facilitate early diagnosis of preterm labor. Of 76 patients at high risk for preterm labor who used daily ambulatory tocodynamometry, approximately half developed preterm labor. Evaluation when the diagnosis of preterm labor was first established has shown that in 8% of the patients the cervix was dilated more than 2 cm, shortened to less than 0.5 cm in 23%, and the fetal membranes were intact in all subjects. The same evaluation in 76 nonrandom contemporary controls matched for risk factors, maternal age, and parity has shown that more than 50% had a cervix dilated more than 2 cm, 38% had a cervix shorter than 0.5 cm, and 24% had rupture of the fetal membranes. Ultimately, 88% of the monitored patients and 59% of controls delivered at term. Comparisons between these groups indicate that intermittent home tocodynamometry may indeed be useful in making the early diagnosis of preterm labor.