CTG stands for cardiotogography and involves two monitors being placed on your belly, held in place with elastic belts. One monitors baby’s heart rate and the other your uterine activity (contractions), and a paper read out tracks both. You may be offered CTG monitoring if you are induced, have a “high risk pregnancy or there are concerns about baby. Alternative methods of monitoring include Pinard fetal stethoscope or a hand held doppler.
A huge meta-analysis of over 118,000 births conducted in April 2021 looked at the use of CTG monitoring versus hands on listening using Pinard fetal stethoscope, handheld Doppler, and other monitoring methods. They found that hands on listening methods reduced the risk of emergency caesarean birth, without increasing adverse neonatal and maternal outcomes. So in short, compared to other monitoring methods, no, CTG does not reduce risk in babies, but it does increase the chances of an unplanned c-section.
You can read the full study here: https://www.cmaj.ca/content/193/14/E468