Aims: To evaluate whether routine medical interventions during labor (oxytocin augmentation, induction, amniotomy, epidural analgesia) condition the outcome of delivery independently of each other and of obstetric risk (calculated in an objective manner). Moreover, to evaluate whether there is an ideal window for initiating such interventions. Methods: Prospective, observational study with 1,047 patients enrolled. Results: Medical interventions were high, whether in low-, medium- or high-risk pregnancies. Oxytocin augmentation (odds ratio 4.678) labour induction (odds ratio 1.717) amniotomy (odds ratio 1.403) and obstetric risk (intermediate- risk odds ratio 1.889, high-risk odds ratio 2.008) increase the probability of an operative delivery. Oxytocin augmentation increases both the probability of a Cesarean delivery and vacuum extraction. Epidural analgesia reduces the probability of cesarean delivery and increases the probability of vacuum extraction. The greater the cervical dilation when oxytocin infusion is initiated, the lower the probability of an operative delivery. The more advanced the cervical dilation and the lower the station when amniotomy or epidural analgesia are carried out, the lower the probability of an operative delivery. Obstetric risk and oxytocin augmentation appear to increase the probability of operative delivery in patients who have undergone amniotomy or epidural analgesia. In addition, labor induction in patients who undergo epidural analgesia increases the risk of operative delivery. Conclusions: Medical interventions during labor are high and cause a rise in operative delivery. Therefore, practitioners should defer it as much as possible. The exception is epidural analgesia because it seems to reduce the number of cesarean sections.