Methods:In this cross-sectional study, 200 primiparous women
participated having a single pregnancy and cephalic presentation.
Uterus contractions were recorded using electronic fetal
monitoring at the beginning of the active phase of labor (dilatation
3-5 cm) for 30 min. Fall to rise (F:R) ratio was calculated by
determining the duration of returning from a contraction peak to
its baseline (fall) and the duration of the rise time from baseline
to peak (rise) in two groups. The data were analyzed using t-test
and Chi-square test.