Introduction:
ST waveform analysis (STAN) was introduced to improve the interpretation of cardiotocography (CTG) resulting in reduction of unnecessary interventions and metabolic acidosis.

Material and Methods:
A search of electronic databases (PubMed, Cochrane, Scopus) was conducted to identify randomized controlled trials (RCTs) in English language. Outcomes considered the operative deliveries, fetal blood sampling (FBS), metabolic acidosis, perinatal and neonatal death, neonatal seizures, neonatal encephalopathy, transfer to the neonatal intensive care unit (NICU) and Apgar score.

Results:
Seven RCTs included in the review. The first two RCTs showed that the combination of STAN and CTG is a better option than using CTG alone, because a reduction in the rate of operative deliveries due to fetal distress and a reduction in metabolic acidosis was documented. The following studies showed no statistically significant changes with the combination of methods, except from a reduction in FBS.

Conclusions:
The findings from the RCTs were different and conflicting. Most studies did not recognize the superiority of the combination in operative deliveries and neonatal outcomes but there were many methodological differences between the trials.