Randomized Control Trial of Second Stage of Labor

The hypothesis of this study is that extending the second stage of labor beyond current American College of Obstetricians and Gynecologists suggestions can reduce the cesarean delivery rate. The cesarean delivery rate in the United States is around 30 percent. This is a number that continues to be increasing over the last few decades and will continue to climb. Each subsequent cesarean section puts the mother and baby at increased risk for postpartum hemorrhage, bowel and bladder injury, abnormal placentation, febrile morbidity and death. The most common reason for a cesarean delivery is a repeat cesarean delivery. One way to reduce this number is to prevent the first cesarean delivery. The aim of this study is evaluate if extending the second stage of labor affects the cesarean delivery rate and subsequent perinatal morbidity.

Consent at the time of admission or in the office 2nd stage starts at full dilation Randomization occurs at 2 hours without epidural or 3 hours with epidural, stratified by epidural status Randomization scheme is according to a predetermined computer-generated block randomization scheme with block sizes of 6,8 and12 (random blocks). Sequentially numbered and sealed opaque envelopes prepared according to the randomization scheme and delivered to a secure container in labor and delivery suite to maintain concealed treatment allocation. At the 3 hour mark, the next number envelope is pulled and opened by the physician/nurse to reveal the designated group. At this point the patient is considered randomized. Provider preference for cesarean delivery, operative vaginal delivery, continued pushing, with intention-to-treat analysis Those that require cesarean delivery - usual perioperative management Early termination criteria: emergency cesarean delivery, category 3 fetal heart tracing

Immediate delivery after 4 hours with an epidural or 3 hours without an epidural Intervention: one additional hour for the second stage of labor Length of second stage in extended arm is 3 hours without epidural and 4 hours with epidural.

At time of delivery, up to 4 hours of the second stage for "Extended group" and 3 hours for "Usual group"

Umbilical artery pH is a marker for adverse neurological outcomes. Umbilical artery pH <7.10 has been proposed as a threshold for identifying fetuses who might develop pathologic fetal acidosis and fetal injury.

3rd or 4th degree laceration or cervical laceration diagnosed at delivery Third degree lacerations extend through the fascia and musculature of the perineal body and involve some or all of the fibers of the external anal sphincter (EAS) and/or the internal anal sphincter. Third degree lacerations are subclassified as follows: 3a: <50 percent of EAS thickness is torn 3b: >50 percent of EAS thickness is torn 3c: IAS is torn (in addition to complete rupture of the EAS) Fourth degree lacerations involve the perineal structures, EAS, IAS, and the rectal mucosa.

Continuous Positive Airway Pressure or Greater (Neonate) Such as Intubation, Mechanical Ventilation, Nasal Intermittent Positive Pressure Ventilation, High-frequency Oscillatory Ventilation

Inclusion Criteria: Nulliparous women singleton pregnancies cephalic presentation 36.0-41.6 weeks age 18 and older Exclusion Criteria: Category 3 fetal heart tracing major congenital anomalies multiples planned cesarean delivery intrauterine fetal demise Trial of labor after cesarean

Gimovsky AC, Phillips JM, Amero M, Levine J, Berghella V. Prolonged second stage effect on pelvic floor dysfunction: a follow up survey to a randomized controlled trial. J Matern Fetal Neonatal Med. 2022 Dec;35(25):5520-5525. doi: 10.1080/14767058.2021.1887122. Epub 2021 Feb 14.

Gimovsky AC, Berghella V. Randomized controlled trial of prolonged second stage: extending the time limit vs usual guidelines. Am J Obstet Gynecol. 2016 Mar;214(3):361.e1-6. doi: 10.1016/j.ajog.2015.12.042.