Electronic fetal monitoring (EFM) is a popular technology used to establish fetal well-being. Despite its widespread use, terminology used to describe patterns seen on the monitor has not been consistent until recently. In 1997, the National Institute of Child Health and Human Development (NICHD) Research Planning Workshop published guidelines for interpretation of fetal tracings. This publication was the culmination of 2 years of work by a panel of experts in the field of fetal monitoring and has been endorsed by both the American College of Obstetricians and Gynecologists (ACOG) and the Association of Women's Health, Obstetric and Neonatal Nurses (AWHONN). The terminology definitions and assumptions found in the NICHD publication form the basis for interpretation of the fetal tracings in this series and are summarized here. Normal values for arterial umbilical cord gas values and indications of acidosis are defined in the Table T1.Decelerations are tentatively called recurrent if they occur with ≥50% of uterine contractions in a 20-minute period.We encourage readers to examine each strip in the case presentation and make a personal interpretation of the findings before advancing to the expert interpretation provided.An 18-year-old G1P0 woman presents to labor and delivery at 39 +6 weeks’ gestation in active labor. She had a normal prenatal course, and her vital signs are stable. Vaginal examination upon admission reveals a cervix dilated 3 to 4 cm, 90% effaced, and 0 station. Uterine contractions are documented as occurring every 5 minutes. An initial fetal tracing is obtained upon admission (Fig. 1).Findings on EFM Strip #1 are: Over the next 3 hours, epidural medication is administered for pain management, membranes are ruptured artificially and clear amniotic fluid is noted, and the fetal scalp electrode is inserted. Vaginal examination shows that the cervix has progressed to 6 to 7 cm dilation, 100% effacement, and the presenting part remaining at 0 station. A fetal tracing is obtained 4 hours after admission (Fig. 2).Findings on EFM Strip #2 are: For the next 3 hours, the FHR remains reassuring, with moderate variability and early decelerations. Maternal vital signs remain stable, with a temperature of99.0°F (37.3°C). Approximately 3½ hours later, vaginal examination reveals the cervix to be completely dilated, with the presenting part at +2 station. The patient begins pushing, and another tracing is obtained (Fig. 3).Findings on EFM Strip #3 are: One hour later, the maternal temperature is 101.7°F (38.8°C) and ampicillin 2 g is administered intravenously. The patient continues to push with the physician at her bedside, and another tracing is obtained (Fig. 4).Findings on EFM Strip #4 are: Forty minutes later, a decision is made to deliver the fetus by cesarean section. The patient is instructed to stop pushing and is prepared for surgery. The maternal temperature has spiked to 103.0°F (39.5°C). A final fetal tracing is obtained (Fig. 5)Findings on EFM Strip #5 are: The final segment of this tracing (Fig. 6) shows an increasing FHR to approximately 200 beats/min. This pattern of tachycardia with absent variability and recurrent decelerations is associated with hypoxia or acidosis. Although uterine contractions are required to determine the presence of late decelerations, the pattern resembles late decelerations in shape and is nonreassuring, necessitating an immediate delivery.A viable male weighing 8 lbs 14 oz is delivered by cesarean section. Apgar scores are 3, 6, and 7 at 1, 5, and 10 minutes, respectively. The infant is transferred to the neonatal intensive care unit for further evaluation and care. The placenta is sent to pathology, and evaluation confirms a diagnosis of early acute chorioamnionitis. The umbilical artery cord gas values demonstrate a mixed respiratory and metabolic acidosis (Table 2), which is consistent with the FHR changes. Long-term outcomes for neonates who have chorioamnionitis are guarded. Chorioamnionitis has been demonstrated to increase the risk of cerebral palsy in the term newborn. The mechanism is currently ill-defined but may be related to the release of cytokines due to a fetal immune response to infection.