Additional file1: Appendix 1. Directedacyclic graph of the exposures, confounders and outcomes in the study. Appendix 2. Count and proportion of adverse outcomes by hourly intervals of 2nd stage duration in nulliparous women. Appendix 3. Count and proportion of adverse outcomes by hourly intervals of 2nd stage duration in parous women. Appendix 4. Flowchart of the population included in the study.