Defining the upper limit of the second stage of labor in nulliparous patients

The Role of Passive Descent and Epidural Analgesia in Outcomes Associated With Prolonged Pushing Among Nulliparous Individuals in Midwifery Care

INTRODUCTION

Efforts to reduce primary cesarean birth may include supporting longer second stages of labor. Although midwifery-led care is associated with lower cesarean use, little has been published on associated outcomes of prolonged second stage (≥3 hours of pushing) for nulliparous individuals in US hospital-based midwifery care. Epidural analgesia and the role of passive descent in midwifery-led care are also underexplored in relation to the second stage. In this study, we report the incidence of prolonged second stage stratified by epidural analgesia and/or passive descent. Secondary aims included calculating the odds of cesarean birth, obstetric anal sphincter injury (OASI), postpartum hemorrhage (PPH), and neonatal complications.

METHODS

Data were collected prospectively from a single academic center in the United States from 2012 through 2019. Our cohort analysis of labors attended by midwives for nulliparous, term, singleton, and vertex pregnancies included both descriptive and inferential statistics comparing outcomes between prolonged versus nonprolonged pushing groups. We stratified the sample and quantified second stage outcomes by epidural analgesia and by use of passive descent.

RESULTS

Of the 1465 births, 17% (n = 247) included prolonged pushing. Cesarean ranged from 2.2% without prolonged pushing to 26.7% with prolonged pushing. Fetal malposition, epidural analgesia, and longer passive descent were more common among those with prolonged active pushing. Despite these factors, neither odds for PPH nor poor neonatal outcomes were associated with prolonged pushing. Those with more than one hour of passive descent in the second stage who also had prolonged active pushing had lower odds for cesarean but higher odds for OASI relative to those who had little passive descent before pushing for more than 3 hours.

DISCUSSION

Prolonged pushing occurred in nearly 2 of 10 nulliparous labors. Fetal malposition, epidural analgesia, and prolonged pushing were commonly observed with longer passive descent, cesarean, and OASI. Passive descent in these data likely reflects individualized midwifery care strategies when pushing was complicated by fetal malposition or other complexities.

The prediction of morbidity related to vaginal delivery in nulliparous women - A secondary analysis from the genesis multicenter trial

OBJECTIVE

In the prospective multicenter Genesis study, we developed a prediction model for Cesarean delivery (CD) in term nulliparous women. The objective of this secondary analysis was to determine whether the Genesis model has the potential to predict maternal and neonatal morbidity associated with vaginal delivery.

STUDY DESIGN

The national prospective Genesis trial recruited 2,336 nulliparous women with a vertex presentation between 39 + 0- and 40 + 6-weeks' gestation from seven tertiary centers. The prediction model used five parameters to assess the risk of CD: maternal age, maternal height, body mass index, fetal head circumference and fetal abdominal circumference. Simple and multiple logistic regression analyses were used to develop the Genesis model. The risk score calculated using this model were correlated with maternal and neonatal morbidity in women who delivered vaginally: postpartum hemorrhage (PPH), obstetric anal sphincter injury (OASI), shoulder dystocia, one- and five-minute Apgar score ≤ 7, neonatal intensive care (NICU) admission, cephalohematoma, fetal laceration, nerve palsy and fractures. The morbidities associated with spontaneous vaginal delivery were compared with those associated with operative vaginal delivery (OVD). The likelihood ratios for composite morbidity and the morbidity associated with OVD based on the Genesis risk scores were also calculated.

RESULTS

A total of 1,845 (79%) nulliparous women had a vaginal delivery. A trend of increasing intervention and morbidity was observed with increasing Genesis risk score, including OVD (p < 0.001), PPH (p < 0.008), NICU admission (p < 0.001), low Apgar score at one-minute (p < 0.001) and OASI (p = 0.009). The morbidity associated with OVD was significantly higher compared to spontaneous vaginal delivery, including NICU admission (p < 0.001), PPH (p = 0.022), birth injury (p < 0.001), shoulder dystocia (p = 0.002) and Apgar score of<7 at one-minute (p < 0.001). The positive likelihood ratios for composite outcomes (where the OVD was excluded) increases with increasing risk score from 1.005 at risk score of 5% to 2.507 for risk score of>50%.

CONCLUSION

In women who ultimately achieved a vaginal birth, we have shown more maternal and neonatal morbidity in the setting of a Genesis nomogram-determined high-risk score for intrapartum CD. Therefore, the Genesis prediction tool also has the potential to predict a more morbid vaginal delivery.