It used to be that when active labor occured, we needed to head to the hospital or call our midwife. Still true, but when is active labor? 4cm you say? Well according to ACOG (American Congress of Obstetricians and Gynecologists') it's really 6cm.
Being a midwife and observing birth, I have to agree. It's important that we understand labor is different for each women and allowing the birth team to arrive when your in active labor, 6cm, will really reduce the interventions then tend to occur so often.
Love this article, read and enjoy: http://www.acog.org/About_ACOG/News_Room/News_Releases/2014/Nations_Ob-Gyns_Take_Aim_at_Preventing_Cesareans