Latent phase of labor in normal patients: a reassessment.

The vaginal examination data (dilation, station, and time) were examined from 2845 consecutive uncomplicated patients who were admitted in early labor to Cleveland Metropolitan General Hospital between January 1, 1979 and December 31, 1982, using data from the computer database of the Perinatal Clinical Research Center. The length of the latent phase of labor was calculated in 2479 of these patients to form the study group. Individual effects of parity and the cervical dilation on the length of the latent phase of labor resembled Friedman's results from 20 years ago. Furthermore, the average and prolonged lengths of the latent phase confirmed that labors have not changed appreciably in 20 years. However, multivariable analysis and standard stepwise regression on all of the vaginal examination data revealed that the largest influence on the length of latent labor was the admitting cervical dilation. Parity had only a small effect when cervical dilation was controlled. Thus, a multiparous patient may progress as slowly as a primiparous patient if they both are admitted with a low cervical dilation.