Changes in fetal movement are associated with increased risk of stillbirth after 28 weeks of pregnancy. The majority of studies have focussed on maternal perception of reduced fetal movements, which is associated with stillbirth via placental dysfunction. Recent studies have also described an association between a single episode of excessive fetal movements and late stillbirth. We present a hypothesis that a sudden episode of excessive fetal activity indicates fetal compromise relating to underlying disturbance of the in utero environment, which if it persists can lead to fetal death. The origin of the excessive fetal movements is unknown; they may represent fetal seizures induced by asphyxia or infection, an attempt to release cord entanglement or a change in fetal behaviour (inducing signs of distress) in response to a noxious stimulus. It is also possible that an increase in maternal anxiety may lead to increased perception of fetal activity.
Current evidence regarding excessive fetal movements is sparse; there is no clinical guidance regarding how reporting of this symptom might relate to a fetus at risk and which management might reduce the risk of subsequent stillbirth. This could be addressed by prospective observational studies of mothers presenting with excessive fetal movements which could both explore the underlying pathophysiology and determine which investigations could identify fetal compromise in this population. The presence of fetal seizures or umbilical cord entanglement could be evaluated at the time of presentation by cardiotocography and ultrasonography of the fetus and cord. Exposure to infection or noxious stimuli could be evaluated by maternal history and measurement of maternal blood for inflammatory markers or toxins. Maternal anxiety could be assessed by validated anxiety scores. Fetal outcome following excessive fetal movements can be recorded after birth. In addition, the presence of perinatal asphyxia can be assessed using Apgar scores, assessment of fetal acidaemia or measurement of stress-related factors in umbilical cord blood. The placenta and cord can be systematically examined for signs of hypoxia, infection or umbilical cord compression. Such studies would provide evidence regarding the underlying cause of excessive fetal movement and how this symptom might relate to in utero compromise and stillbirth. Ultimately, this approach will determine whether excessive fetal movements can be used alongside reduced fetal movements as a tool to reduce the perinatal mortality rate.