The main purpose of using a partograph in labor is to prevent prolonged labor by providing a graphical record of labor progress. It helps healthcare providers monitor cervical dilation, fetal descent, and uterine contractions in real-time. Early identification of deviations from normal labor patterns allows timely intervention, reducing risks of maternal and fetal complications such as obstructed labor or fetal distress. Thus, the partograph is an essential tool for ensuring timely decision-making to improve labor outcomes.

Reference: Williams Obstetrics, Cunningham et al., 25th Edition.