There is a benefit to using EFM in women with complicated labors, such as those induced or augmented with oxytocin, prolonged labors, vaginal birth after having a cesarean section, abnormal presentation, and twin pregnancy.
The EFM is applied to her abdomen by two straps: one is to listen to the FHR by means of a transducer, and the other is to pick up any contractions by pressure on a tocodynameter.
For these and other reasons, the United States Preventive Services Task Force states that there is some evidence that using EFM on low-risk women in labor might not be indicated.
The EFM continuously prints out a record of both the FHR and the duration and frequency of the uterine contractions, so that deviations from normal patterns can be identified.
The NST is performed with an electronic fetal monitor (EFM) that traces the fetal heart rate (FHR) and the presence of any contractions on a monitor strip.