Evaluation of duration of active phase of labor and the factors influencing it in Shariatti Hospital, Tehran

In a descriptive study on 791 cases of normal vaginal deliveries within the period of 6 months (20th Sept 1994-20th March 1995) in Shariatti hospital, the duration of active phase of labor was evaluated. In 140 pregnant women (69 primigravida and 71 multipara) which had the inclusion criteria (single fetus, cephalic presentation, 37 to 42 weeks of pregnancy, admission before cervical dilatation of 3-4 cm, no need for augmentation of labor, forceps-vaccum or cesarean section) the mean duration for 1st stage was 2.31 hrs in primigravid and 1.56 hrs in multipara, for 2nd stage was 35 minutes in primigravid and 17.5 minutes in multipara. Maternal age, parity and fetal birth weight had influence on the duration of labor. Maternal age and parity each had independent and also additive effects on the duration of labor. Fetal birth weight of >3500 gr in multipara and >4000 gr in primipara caused lengthening of the duration of labor