Neonatal complications during labor are primarily associated with metabolic acidosis due to oxygen deficit (hypoxia) resulting in anaerobic metabolism. The aim of fetal monitoring is to detect early signs of fetal hypoxia so that timely and appropriate interventions can be instituted to avoid or reduce concomitant fetal injuries.

The present STAN® system was developed for early detection of metabolic acidosis due to hypoxia in human fetuses and thus to prevent hypoxic ischemic encephalopathy more efficiently than cardiotocography in combination with fetal scalp blood sampling. Another prospect was the possibility to avoid unnecessary Cesarean sections and instrumental deliveries.

This systematic review has evaluated 27 studies of which six were included in the qualitative assessment. The four randomized controlled studies comprising more than 12 000 patients altogether were included in metaanalyses. The level of evidence was assessed using the GRADE system.


  • There is insufficient scientific evidence answer the question if use of the STAN® technology reduces the risk of metabolic acidosis in neonates. The level of existing evidence is very low and further research is needed (⊕).
  • The rates of Cesarean sections and instrumental deliveries for fetal distress or other indications are the same for both methods studied. The level of evidence is moderate (⊕⊕⊕).
  • STAN® reduces the rate of fetal scalp blood sampling. The level of evidence is moderate (⊕⊕⊕).
  • There is not enough data to allow conclusions regarding the effects of STAN® monitoring on the risk of hypoxic ischemic encephalopathy.

This Health Technology Assessment has been conducted Roger Bottinga, Gunvor Ekman-Ordeberg, Eva Eneroth-Grimfors, Ulf Hanson, all specialists in obstetrics and gynecology, Ingela Wiklund, midwife and Anette Salmelin, med.stud, cooperation with Elisabeth Persson and Peter Gunvén, both medical advisers, and their team, at the HTA-center in Stockholm County Council-Region Gotland, Sweden.

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