I just went and checked and I was slightly wrong about the methodology. The comparison was actually between continuous electronic monitoring and manual listening with a stethoscope. I would hope/expect that a nurse is coming to visually inspect a laboring woman at least once per hour regardless.

This [0] is one of the studies cited by the book where I learned about this phenomenon. Continous monitoring was found to have a higher incidence of c-section and forceps deliveries. The only condition where continuous monitoring came out ahead was in detecting seizures.

[0] https://www.cochranelibrary.com/cdsr/doi/10.1002/14651858.CD...