The course of labor in term patients with chorioamnionitis.

Labor records and internal fetal monitor tracings of 65 patients with uncomplicated term pregnancies who entered labor spontaneously and then developed chorioamnionitis were reviewed. Eighty-eight percent of patients were nulliparous. Seventy-five percent had abnormal labor, characterized by decreased uterine contractility, and 34% required cesarean delivery because of failure to progress in labor. The most common fetal heart rate abnormalities were diminished or absent variability (77%) and tachycardia (67%); 15% of the tracings had a sinusoidal pattern. Despite the high prevalence of abnormal fetal heart rate tracings, only one infant had a 5-minute Apgar score less than 7. It is concluded that chorioamnionitis has an inhibitory effect on labor. Compared to uninfected women, certain infected patients appear to require higher doses of oxytocin and greater uterine activity to effect a given change in cervical dilation.