Single sporadic deceleration during reactive nonstress test – clinical significance and risk for cesarean delivery

Abstract Purpose: The non-stress test (NST) is the most widely applied technique for antepartum fetal assessment with the goal to reduce stillbirth. The evidence regarding the clinical significance of a single sporadic variable deceleration (SSD) in reactive NST is scarce, and optimal management has yet been established. We aim to evaluate whether SSD during a reactive NST at term is associated with a higher risk for fetal heart rate decelerations during labor and the need for intervention. Methods: A retrospective, case-control study of singleton, term pregnancies at one university-affiliated medical center in 2018. Study group consisted of all pregnancies with an SSD in an otherwise reactive NST. For each case, two consecutive pregnancies without SSD were matched in a 1:2 ratio. The primary outcome was the rate of cesarean delivery (CD) due to non-reassuring fetal heart rate monitoring (NRFHRM). Results: 84 women with a diagnosis of SSD were compared to 168 controls. SSD during antenatal fetal surveillance was not associated with the presence of fetal heart rate decelerations during labor and did not increase the rate of CD overall or for NRFHRM (17.9% vs. 13.7% and 10.7% vs. 7.7%, study vs. control group, respectively, p>0.05). Likewise, rates of assisted deliveries, maternal outcomes, and neonatal complications were similar between the groups. Conclusions: SSD during a reactive NST in term pregnancies is not associated with an increased risk for adverse perinatal outcomes. Expectant management should be considered in pregnancies with SSD at term.