•have regional analgesia
•have any analgesia/anesthesia
•give birth with vacuum extraction or forceps
•give birth by cesarean
•have a baby with a low 5-minute Apgar score
•report dissatisfaction or a negative rating of their experience.
•give birth spontaneously (that is, with neither cesarean nor vacuum extraction nor forceps)
•have a shorter labor.
This is obviously just a quick synopsis of the most important aspects. For mote information on how the study was conducted or more details on the results you can check it out here or here.