Second-stage labor: consensus versus science.

There has been a recent significant evolution in suggested practices for the management of labor because of the increased national cesarean delivery rate. One of the most significant changes was promulgated by the 2014 Obstetric Care Consensus entitled, "Safe Prevention of Primary Cesarean Delivery," which recommended reconsideration of the upper limits of the length of labor in the second stage as well as the first stage. We previously published a 2016 Clinical Opinion challenging the second-stage practice change. Over the past 2 years, there have been at least 5 reports as well as 2 national organization statements supporting revised management of second-stage labor. We now revisit the second-stage issue because we believe that it is important to carefully clarify the current status resulting from consensus statements as well as the evolving current status of scientific evidence. We structured this Clinical Opinion using questions in an effort to chronicle the story of how obstetric precepts on second-stage labor in use for more than 50 years were being replaced. How did we get here? What is the current evidence? What can be learned from this experience? Should American obstetrics now "fall back" to pre-existing obstetric precepts for the management of second-stage labor after having "sprung forward" an additional hour-namely, lengthening the duration of acceptable second-stage labor to 4 hours as recommended by the Obstetric Care Consensus? We believe that the data published since our 2016 Clinical Opinion buttress our original position that prolongation of the second stage beyond historical precepts is unsafe.