title: ST waveform analysis versus cardiotocography alone for intrapartum fetal monitoring: a systematic review and meta-analysis of randomized trials.
abstract: BACKGROUND
  ST waveform analysis was introduced to reduce metabolic acidosis at birth and avoid unnecessary operative deliveries relative to conventional cardiotocography. Our objective was to quantify the efficacy of ST waveform analysis vs. cardiotocography and assess the quality of the evidence using the Grading of Recommendations Assessment, Development and Evaluation tool.
  
  
  METHODS
  We identified randomized controlled trials through systematic literature searches and assessed included studies for risk of bias. Meta-analyses were performed, calculating pooled risk ratio or peto odds ratio. We performed post hoc trial sequential analyses for selected outcomes to assess the risk of false-positive results and the need for additional studies.
  
  
  RESULTS
  Six randomized controlled trials were included in the meta-analysis. ST waveform analysis was not associated with a reduction in operative deliveries due to fetal distress, but we observed a significantly lower rate of metabolic acidosis (peto odds ratio 0.64; 95% confidence interval 0.46-0.88). Accordingly, 401 women need to be monitored with ST waveform analysis to prevent one case of metabolic acidosis. No statistically significant effects were observed in other fetal or neonatal outcomes, except from fetal blood sampling (risk ratio 0.59; 95% confidence interval 0.45-0.79) and a minor reduction in the number of operative vaginal deliveries for all indications (risk ratio 0.92; 95% confidence interval 0.86-0.99). The quality of the evidence was high to moderate.
  
  
  CONCLUSIONS
  Absolute effects of ST waveform analysis were minor, and the clinical significance of the observed reduction in metabolic acidosis is questioned. There is not enough evidence to justify the use of ST waveform analysis in contemporary obstetrics.
authors.affiliation: Faculty of Health Sciences, Oslo and Akershus University College of Applied Sciences, Oslo, Norway.
authors.forename: Ellen
authors.identifier: http://orcid.org/0000-0001-7971-4580
authors.initials: E
authors.lastname: Blix
authors.affiliation: The Norwegian Knowledge Center for the Health Services, Oslo, Norway.|Center for Evidence Based Practice, Bergen University College, Bergen, Norway.
authors.forename: Kjetil G
authors.identifier: http://orcid.org/0000-0002-5920-4652
authors.initials: KG
authors.lastname: Brurberg
authors.affiliation: Science and Health Library, University Library, UiT The Arctic University of Norway, Tromsø, Norway.
authors.forename: Eirik
authors.identifier: http://orcid.org/0000-0001-8877-2192
authors.initials: E
authors.lastname: Reierth
authors.affiliation: The Norwegian Knowledge Center for the Health Services, Oslo, Norway.
authors.forename: Liv M
authors.identifier: http://orcid.org/0000-0002-8135-848X
authors.initials: LM
authors.lastname: Reinar
authors.affiliation: Department of Obstetrics and Gynecology, University Hospital of North Norway, Tromsø, Norway.|Department of Clinical Medicine, UiT The Arctic University of Norway, Tromsø, Norway.
authors.forename: Pål
authors.initials: P
authors.lastname: Øian
mesh_terms: D000138:Acidosis / Q000517:prevention & control*; D015148:Cardiotocography; D036861:Delivery, Obstetric / Q000706:statistics & numerical data; D004562:Electrocardiography; D005260:Female; D005316:Fetal Distress / Q000175:diagnosis; D006801:Humans; D007743:Labor, Obstetric; D061366:Numbers Needed To Treat; D011247:Pregnancy; D016032:Randomized Controlled Trials as Topic
keywords: ST waveform analysis; cardiotocography; fetal electrocardiography; intrapartum fetal monitoring; meta-analysis