New evidence suggests that the active phase of labor does not begin until 6 centimeters. It seems that much has been misunderstood about childbirth and the stages of labor being currently used is in need of a revision.
The recognition of active labor beginning at 4 centimeters based upon Friedman’s curve has been poorly studied but widely used since the 1950s as the standard of progress in labor. Current studies show normal labor patterns vary widely and are not in keeping with Friedman’s curve which was based upon a sample of 500 Caucasian women.
What has been diagnosed as an abnormal labor pattern based upon 4 cm may have led to unnecessary interventions and cesareans. When active labor becomes more widely diagnosed as 6 cm this could have a dramatic impact upon decreasing interventions and the cesarean rate.
The new saying: “6 centimeters is the new 4 centimeters”