Objective: In a previous randomized trial that compared monitoring uterine contractions with an intrauterine pressure catheter (IUPC) versus external monitoring, we demonstrated that use of an IUPC did not improve the outcome of labor. To provide insight in the lack of a positive effect, we evaluated level of IUP in Montevideo units (MU) in correlation with dysfunctional labor and adverse neonatal outcome.Study design: Here, we present two secondary analyses on the 503 women who had IUP measured in the trial. Firstly, we assessed labor outcome in relation to the highest IUP measured at any time during labor. Secondly, we assessed labor outcome to the IUP registered at the last vaginal examination during the first stage of labor in two study groups (above and below 200 MU).Results: Women with lower IUP were statistically significant older, had pregnancies with a longer gestational age, longer labors and neonates with a higher birth weight. The risk of a cesarean section was higher in women who had low IUP during labor (Likelihood Ratio 1.6 for IUP300 MU). IUP was not associated with neonatal outcome.Conclusion: IUP is associated with mode of delivery. However, use of internal tocodynamometry does not improve birth outcomes.