Cohen (1977) investigated the fetal efects of second-stage labor length at Beth Israel Hospital. He included 4403 term nulliparas in whom electronic fetal heart rate monitoring was performed. he neonatal mortality rate was not increased in women whose second-stage labor exceeded 2 hours. Epidural analgesiawas used commonly, and this likely accounted for the large number of pregnancies with a prolonged second stage. These data inluenced decisions to permit an additional hour for the second stage when regional analgesia is used.
Menticoglou and coworkers (1995a,b) also challenged the prevailing dicta on second-stage duration. Their concern stemmed from grave neonatal injuries associated with forceps rotations to shorten second-stage labor. As a result, they allowed a longer second stage to decrease the operative vaginal delivery rate. Between 1988 and 1992, second-stage labor exceeded 2 hours in a fourth of 6041 nulliparas at term. Labor epidural 4 0)) 3.�i0C)E 20:0E)0). 0
Year of delivery
FIGURE 23-4 Primary caesarean delivery rates for dystocia in lowrisk women at term at Parkland Hospital from 1988 to 2017.
analgesia was used in 55 percent. he length of the second stage, even in those lasting up to 6 hours or more, was not related to neonatal outcome. hese results were attributed to careful use of electronic monitoring and scalp pH measurements. hese investigators concluded that there is no compelling reason to intervene with a possibly diicult forceps or vacuum extraction because a certain number of hours have elapsed. hey observed, however, that after 3 hours in the second stage, delivery by cesarean or other operative method increased progressively. By 5 hours, the prospects for spontaneous delivery in the subse quent hour were only 10 to 15 percent.
Newer guidelines have been promoted by the Consensus Com mittee (2016) for second-stage labor. These recommend allowing a nullipara to push for at least 3 hours and a multipara to push for at least 2 hours before second-stage labor arrest is diagnosed.
One caveat is that maternal and fetal status should be reassuring.
hese authors provide options to these times before cesarean deliv ery is performed. Namely, longer durations may be appropriate as long as progress is documented. Also, a speciic maximal length of undergo operative delivery has not been identiied.
Intuitively, the goal to lower cesarean delivery rates is best balanced with one to ensure neonatal safety. And, it is problematic that no robust data on neonatal outcomes support the safety of allowing prolonged second-stage labor. Data from many evaluations reveal that serious newborn consequences attend second-stage labors longer than 3 hours (Allen, 2009; Bleich, 2012; Laughon, 2014; Leveno, 2016; Rosenbloom, 2017). Other data, when adjusted for labor variables, show no diference in neonatal complications for these longer second stages (Cheng, 2004; Le Ray, 2009; Rouse, 2009). Grobman and colleagues (2016) have argued that the absolute number of such adverse outcomes is small and "overall outcomes remain good." hat said, some of the complications are severe. Thus, to fully ascertain specific efect of these guidelines on morbidity rates, randomized controlled trials are needed.