The role of a trial of labor with a positive contraction stress test.

During a 28 month period 812 patients underwent antepartum FHR testing. Twenty-eight patients had a positive CST. There were two antepartum fetal deaths and 11 patients had a cesarean section without a trial of labor. Fifteen patients had a trial of closely monitored labor (continuous FHR and fetal scalp blood sampling when indicated) and 11 of these (73%) were delivered vaginally. The CST records were examined for: per cent late deceleration, baseline FHR, presence of FHR accelerations, duration of the latency period (time from onset of contraction to onset of deceleration), and amplitude of deceleration. The absence of accelerations (nonreactive CST) and a latency period of less than 45 seconds both predicted persistent late deceleration during labor or fetal death in utero but statistical significance was found only for the latter parameter.