The second stage of labor

The second stage of labor extends from complete cervical dilatation to delivery. During this stage, descent and rotation of the presenting part occur as the fetus passively negotiates its passage through the birth canal. Generally, descent begins during the deceleration phase of dilatation as the cervix is drawn upward around the fetal presenting part. The most common means of assessing the normality of the second stage of labor is to measure its duration, but progress can be more meaningfully gauged by measuring the change in fetal station as a function of time. Accurate clinical identification and evaluation of differences in patterns of fetal descent are necessary to assess second stage of labor progress and to make reasoned judgments about the need for intervention. Three distinct graphic abnormalities of the second stage of labor can be identified: protracted descent, arrest of descent, and failure of descent. All abnormalities have a strong association with cephalopelvic disproportion but may also occur in the presence of maternal obesity, uterine infection, excessive sedation, and fetal malpositions. Interpretation of the progress of fetal descent must be made in the context of other clinically discernable events and observations. These include fetal size, position, attitude, and degree of cranial molding and related evaluations of pelvic architecture and capacity to accommodate the fetus, uterine contractility, and fetal well-being. Oxytocin infusion can often resolve an arrest or failure of descent or a protracted descent caused by an inhibitory factor, such as a dense neuraxial block. It should be used only if thorough assessment of fetopelvic relationships reveals a low probability of cephalopelvic disproportion. The value of forced Valsalva pushing, fundal pressure, and routine episiotomy has been questioned. They should be used selectively and where indicated.

The use of bubble charts in analyzing second stage cesarean delivery rates

BACKGROUND

The incidence of second stage cesarean delivery has been rising globally because of the failure or the anticipated difficulty of performing instrumental delivery. Yet, the best way to interpret the figure and its optimal rate remain to be determined. This is because it is strongly influenced by the practice of other 2 modes of birth, namely cesarean delivery performed before reaching the second stage and assisted vaginal birth during the second stage. In this regard, a bubble chart that can display 3-dimensional data through its x-axis, y-axis, and the size of each plot (presented as a bubble) may be a suitable method to evaluate the relationship between the rates of these 3 modes of births.

OBJECTIVE

This study aimed to conduct an epidemiologic study on the incidence of second stage cesarean deliveries rates among >300,000 singleton term births in 10 years from 8 obstetrical units and to compare their second stage cesarean delivery rates in relation to their pre-second stage cesarean delivery rates and assisted vaginal birth rates using a bubble chart.

STUDY DESIGN

The territory-wide birth data collected between 2009 and 2018 from all 8 public obstetrical units (labelled as A to H) were reviewed. The inclusion criteria were all singleton pregnancies with cephalic presentation that were delivered at term (≥37 weeks' gestation). Pre-second stage cesarean delivery rate was defined as all elective cesarean deliveries and those emergency cesarean deliveries that occurred before full cervical dilatation was achieved as a proportion of the total number of births. The second stage cesarean delivery rate and assisted vaginal birth rate were calculated according to the respective mode of delivery as a proportion of the number of cases that reached full cervical dilatation. The rates of these 3 modes of births were compared among the parity groups and among the 8 units. Using a bubble chart, each unit's second stage cesarean delivery rate (y-axis) was plotted against its pre-second stage cesarean delivery rate (x-axis) as a bubble. Each unit's second stage cesarean delivery to assisted vaginal birth ratio was represented by the size of the bubble.

RESULTS

During the study period, a total of 353,434 singleton cephalic presenting term pregnancies were delivered in the 8 units, and 180,496 (51.1%) were from nulliparous mothers. When compared with the multiparous group, the nulliparous group had a significantly lower pre-second stage cesarean delivery rate (18.58% vs 21.26%; P<.001) but a higher second stage cesarean delivery rate (0.79% vs 0.22%; P<.001) and a higher assisted vaginal birth rate (17.61% vs 3.58%; P<.001). Using the bubble of their averages as a reference point in the bubble chart, the 8 units' bubbles were clustered into 5 regions indicating their differences in practice: unit B and unit H were close to the average in the center. Unit A and unit F were at the upper right corner with a higher pre-second stage cesarean delivery rate and second stage cesarean delivery rate. Unit D and unit E were at the opposite end. Unit C was at the upper left corner with a low pre-second stage cesarean delivery rate but a high second stage cesarean delivery rate, whereas unit G was at the opposite end. Unit C and unit G were also in the extremes in terms of pre-second stage cesarean delivery to assisted vaginal birth ratio (0.09 and 0.01, respectively). Although some units seemed to have very similar second stage cesarean delivery rates, their obstetrical practices were differentiated by the bubble chart.

CONCLUSION

The second stage cesarean delivery rate must be evaluated in the context of the rates of pre-second stage cesarean delivery and assisted vaginal birth. A bubble chart is a useful method for analyzing the relationship among these 3 variables to differentiate the obstetrical practice between different units.

Prolonged second stage of labor: Predictors of adverse maternal and perinatal outcomes in a sub-Saharan setting

OBJECTIVE

To determine the predictors of adverse maternal and perinatal outcomes among parturients with prolonged second stage of labor.

METHODS

This study is a cross-sectional study of women with prolonged second stage of labor from January 1 to June 30, 2021, in four tertiary hospitals in Ethiopia. Data were collected prospectively using a structured questionnaire. Descriptive statistics were used to analyze baseline characteristics. Bivariate and multivariate logistic regression analyses were applied to determine predictors of adverse maternal and perinatal outcomes.

RESULTS

A total of 406 women were included in the study. More than half (25/46, 54%) of the women with a prolonged second stage of 4 h or longer had vaginal delivery, which was lower than the 73% (140/190) of women who had a second stage of 2-3 h and the 63.4% (64/101) of women with a second stage duration of 3-4 h. Duration of second stage of labor was not a predictor of composite adverse maternal outcomes nor was it a predictor of adverse perinatal outcome. Operative vaginal delivery (adjusted odds ratio [aOR] 6.0, 95% confidence interval [CI] 2.41-14.9) and nulliparity (aOR 4.1, 95% CI 1.58-10.41) were predictors of adverse maternal outcome, but nulliparity (aOR 1.8, 95% CI 1.05-3.04) and duration of rupture of membranes greater than 18 h (aOR 2.4, 95% CI 1.21-4.93) were predictors of adverse perinatal outcomes.

CONCLUSION

Under strict fetal and maternal well-being monitoring, women with a prolonged second stage of labor can labor for an additional 2 h (up to a total of 4 h) without increasing adverse maternal and neonatal outcomes.

Duration of the second stage of labour and risk of subsequent spontaneous preterm birth

OBJECTIVES

To determine the risk of spontaneous preterm birth (sPTB) associated with the length of second stage of labour in the first term delivery.

DESIGN

Retrospective cohort study.

SETTING

University hospital.

POPULATION

Women with first two consecutive singleton births and the first birth at term. Those who did not reach the second stage of labour in the first delivery were excluded.

METHODS

Charts from 2007 to 2019 were reviewed.

MAIN OUTCOME MEASURES

Rate of sPTB (<37 weeks of gestation) in the second delivery.

RESULTS

Of 13 958 women who met study inclusion criteria, 1464 (10.5%) parturients had a prolonged second stage (≥180 min) in their first term delivery. The rate of sPTB in the second delivery was similar in those with and without a prolonged second stage in first delivery (2.8% versus 2.8%; adjusted odds ratio [aOR] 1.35, 95% CI 0.96-1.90). After adjustment for mode of delivery, prolonged second stage was also not associated with subsequent sPTB in those who delivered by spontaneous and operative vaginal delivery. Those delivered by second-stage caesarean section in the first delivery had a higher risk of sPTB in the second delivery (25/526, 4.8%; aOR 2.66, 95% CI 1.71-4.12; p < 0.001), with a more pronounced risk in those with second-stage caesarean following a prolonged second stage of labour (15/259, 5.8%; aOR 3.40, 95% CI 1.94-5.94; p < 0.001).

CONCLUSION

Second-stage duration in a first term vaginal delivery is not associated with subsequent sPTB. The risk of sPTB is increased following second-stage caesarean section, particularly if performed after a prolonged second stage.

Evidence-based labor management: second stage of labor (part 4)

Several interventions during the second stage of labor have been identified and investigated. Prophylactic intrapartum betamimetics should be avoided, as their usage is associated with an increase in operative vaginal deliveries. Women without epidural anesthesia are recommended to give birth in in any upright or lateral position. The best position for giving birth in women with epidural anesthesia is insufficiently studied, and neither recumbent nor upright positions can therefore be recommended. The routine use of maternal stirrups in the second stage of labor is not recommended. Consider avoiding water immersion during the second stage of labor, as the risks have not been adequately assessed. In nulliparous women at term with epidural analgesia, delayed pushing is not recommended. Pushing via a woman's own urge to push (open glottis) or pushing using the Valsalva maneuver (closed glottis) can both be considered. Both traditional coaching during pushing and ultrasound-assisted coaching may be considered. The use of a dental support device can be considered. All forms of fundal pressure are not recommended in the second stage of labor. Perineal massage and stretching of the perineum with a water-soluble lubricant in the second stage of labor is recommended. Perineal hyaluronidase injection as a method to reduce perineal trauma is not recommended. The use of perineal gel in the second stage of labor is not recommended. The use of perineal warm packs and heating pads are recommended. A perineal protection device can be considered. In fetuses with persistent occiput posterior position, manual rotation can be considered. Routine use of the Ritgen's maneuver does not seem to be associated with any benefits and is not recommended. The "Hands-poised" position is recommended over the "hands-on" method for delivery of the fetus. Routine episiotomy is not recommended. The routine use of ultrasound in the second stage of labor is not recommended. Waiting 1 additional hour (4 hours) for nulliparous women with epidural anesthesia before the diagnosis of a prolonged second stage of labor is recommended. A mandatory second opinion before cesarean delivery in the second stage of labor is recommended.

Does the length of second stage of labour or second stage caesarean section in nulliparous women increase the risk of preterm birth in subsequent pregnancies?

OBJECTIVES

This study aimed to investigate the role of prolonged second stage of labour and second stage caesarean section on the risk of spontaneous preterm birth (sPTB) in a subsequent pregnancy.

METHODS

This was a retrospective cohort study of nulliparous women with two consecutive singleton deliveries between 2014 and 2017 at a tertiary centre. In the vaginal delivery cohort, subsequent pregnancy outcomes for women with a prolonged second stage (>2 h) were compared with those with a normal second stage (≤2 h). In the caesarean delivery cohort, women with a first stage or a second stage were compared with the vaginal delivery cohort. The primary outcome was subsequent sPTB.

RESULTS

A total of 821 women met inclusion criteria, of which 74.8% (614/821) delivered vaginally and 25.2% (207/821) delivered by caesarean section. There was no association between a prolonged second stage in the index pregnancy and subsequent sPTB (aOR 0.70, 95% CI 0.13-3.83, p=0.7). The risk of subsequent sPTB was threefold for those with a second stage caesarean section; however this did not reach statistical significance.

CONCLUSIONS

A prolonged second stage of labour in the index pregnancy is not associated with an increased risk of subsequent sPTB. A second stage caesarean section in the index pregnancy may be associated with an increased risk of subsequent sPTB, however there was no statistically significant difference. These findings are important for counseling and suggest that the effects of these factors are not clinically significant to justify additional interventions in the subsequent pregnancy.

Extending the second stage of labor in nulliparous women with epidural analgesia: a cost-effectiveness analysis

The objective of this study was to evaluate maternal outcomes with an extended second stage of labor and determine if an extended second stage is cost effective. This theoretical model evaluated expectant management to 4 h compared to delivery at 3 h in the setting of a prolonged second stage of labor in nulliparous women with epidural analgesia. In our theoretical cohort of 165,000 women, we found that an extended second stage resulted in 53,268 more spontaneous vaginal deliveries, 14,163 fewer operative vaginal deliveries, and 39,105 fewer cesarean deliveries. This approach also resulted in 1 fewer instance of maternal death. An extended second stage, however, led to 14,025 more cases of chorioamnionitis, 1699 more episodes of postpartum hemorrhage requiring transfusion, and 119 more severe perineal lacerations, suggesting that while an extended second stage of labor results in overall improved maternal outcomes, there are tradeoffs. Expectant management to 4 h was the dominant strategy in the model, as it saved over $114 million US dollars and resulted in 4000 additional QALYs over our theoretical cohort. Sensitivity analysis indicated that expectant management until 4 h was cost-effective as long as the probability of cesarean delivery at 4 h was below 41.8%, and was the dominant strategy below 38.2% (baseline input: 19.5%). Multivariable sensitivity analysis demonstrated that the model was robust over a wide range of assumptions. Expectant management of the second stage of labor until 4 h is a cost-effective strategy to prevent primary cesarean deliveries, decrease costs, and improve some maternal outcomes, despite tradeoffs.

Postpartum urinary retention in women undergoing instrumental delivery: A cross-sectional analytical study

INTRODUCTION

Women undergoing instrumental delivery are known to be at higher risk of urinary retention, which can lead to long-term complications such as voiding dysfunction. Nulliparous women undergo a pronounced and sudden change in the perineum due to stretching during delivery, which may add to the perineal trauma from an episiotomy, increasing the risk of urinary retention. We aim to study the incidence and risk factors associated with postpartum urinary retention in women undergoing instrumental delivery.

MATERIAL AND METHODS

Pregnant women who had an instrumental delivery after 37 weeks of gestation at JIPMER, Puducherry, India, between January 2017 and June 2017 were included in the study. Postpartum urinary retention was defined as the inability to void spontaneously or ultrasonographic documentation of post-void residual volume of >150 mL, 6 hours after delivery. Demographic factors, clinical profile and follow-up of these patients were noted. Multivariate logistic regression analysis was performed to assess the risk factors associated with urinary retention and was presented as adjusted odds ratios (OR) with 95% confidence intervals (CI).

RESULTS

Postpartum urinary retention was noted in 124 (20.6%) women undergoing instrumental delivery. Overt and covert urinary retention occurred in 2.3% and 18.3%, respectively. After adjusting for other risk factors, nulliparity (adjusted OR = 4.05, 95% CI 2.02-8.12 compared with multiparity) and prolonged second stage (OR = 3.96, 95% CI 1.53-10.25) compared with suspected fetal compromise as an indication for instrumental delivery was associated with increased risk of postpartum urinary retention. Interaction was noted between parity and episiotomy on the occurrence of postpartum urinary retention (P = .010). Among nulliparous women, those with episiotomy (adjusted OR = 6.10, 95% CI 2.65-14.04) have higher odds of developing postpartum urinary retention compared with those without episiotomy.

CONCLUSIONS

Approximately one of five (20.6%) women undergoing instrumental delivery developed postpartum urinary retention. Among women undergoing instrumental delivery, episiotomy increased the chances of developing postpartum retention in nulliparous but not multiparous women. Prolonged second stage as an indication for instrumental delivery also increased the chances of retention. Future studies are needed to define the cutoff for diagnosis and to evaluate the long-term effects of covert postpartum urinary retention, as well to study the effect of episiotomy on development of postpartum urinary retention in women undergoing instrumental delivery.

Pushing the limits: perinatal outcomes beyond prolonged second stage

Objective: To evaluate whether extremely prolonged second stage of labor in nulliparous women affects mode of delivery and perinatal outcomes.Methods: We performed a retrospective cohort study of nulliparous women with singleton gestations and cephalic presentation who reached 10 cm of cervical dilation at gestational age 36 0/7-41 6/7. Women were stratified by epidural status. Deliveries were compared by length of second stage: 0-179 min (normal second stage, NSS), 180-299 min (prolonged second stage, PSS), and ≥300 min (extremely prolonged second stage, EPSS). Primary outcome was incidence of vaginal delivery. Secondary outcomes were maternal and neonatal morbidities.Results: Six hundred sixty-one women were evaluated; overall, 92.7% (613/661) of the patients delivered vaginally, with 84.6% (559/661) of women undergoing spontaneous vaginal delivery. In women with epidural anesthesia, 90.6% (446/492) delivered vaginally (97.2% of NSS, 95.1% of PSS, and 69.2% of EPSS). In women without epidural anesthesia, 98.8% (167/169) delivered vaginally (99.3% of NSS, 100.0% of PSS, and 87.5% of EPSS). Women with epidural anesthesia and EPSS had a higher rate of postpartum hemorrhage (aOR: 8.52; 95% CI: 3.99-18.19) and third-degree laceration when compared to NSS (aOR: 5.87; 95% CI: 1.71-20.17). EPSS neonates had a higher rate of CPAP use (OR: 3.99; 95% CI: 1.82-8.74) and significantly higher birth weight (p < .0001) and composite neonatal outcomes (OR: 4.98; 95% CI: 2.34-10.59) compared to NSS.Conclusion: In nulliparous women at term with singleton gestations who reached second stage, the chance of vaginal delivery was 92.7%; even after 5 h of second stage, most women delivered via vaginal delivery (70.4%, 81/115). In those with epidural anesthesia, the PSS group had similar perinatal outcomes as the NSS group, whereas the EPSS group had significantly worse perinatal outcomes. Second stage ≥5 h is a potential tipping point for hazardous perinatal outcomes.

Length of the second stage of labor and preterm delivery risk in the subsequent pregnancy

BACKGROUND

Cervical injury is regarded as an important risk factor for preterm delivery. A prolonged second stage of labor may increase the risk of cervical injury that, in turn, may be associated with increased risk of spontaneous preterm delivery in the subsequent pregnancy.

OBJECTIVE

We sought to evaluate whether the duration of the second stage of labor in a term primiparous singleton delivery is associated with an increased risk of singleton spontaneous preterm delivery (<37 weeks) in the second pregnancy.

STUDY DESIGN

We carried out a retrospective cohort analysis of women with 2 consecutive pregnancies: a first term (≥37 weeks) delivery and second birth. Data were derived from a single institution's prospectively collected obstetrical database from January 2005 through January 2015. Duration of the second stage of labor was examined as a continuous variable, modeled based on nonparametric restricted cubic regression spline with 4 degrees of freedom. Second-stage duration was also examined as short (<30 minutes), normal (30-179 minutes), and prolonged, defined as ≥180 minutes. The association between the duration of the second stage of labor in the first term pregnancy and the risk for spontaneous preterm delivery in the second pregnancy was evaluated before and after adjusting for potential confounders based on the Cox proportional hazards regression model. Associations were expressed based on the adjusted hazard ratio and 95% confidence interval.

RESULTS

In all, 6715 women met inclusion criteria. The hazard of spontaneous preterm delivery in the second pregnancy trended higher with both shorter and longer second-stage labors. The length of the second stage of labor in the first term delivery was categorized as short (<30 minutes) in 1749 (26.0%), normal (30-179 minutes) in 4551 (67.8%), and prolonged (≥180 minutes), in 415 (6.2%) women. Of these 6715 women with a first term delivery, 4.2% (n = 279) delivered spontaneously preterm in the second pregnancy. The risks of spontaneous preterm delivery among women with prolonged (≥180 minutes) second stage of labor and normal labor duration (30-179 minutes) were 5.4% (n = 22) and 3.5% (n = 158), respectively (adjusted hazard ratio, 1.81; 95% confidence interval, 1.15-2.84). This increased risk for prolonged second stage of labor was primarily seen among women who underwent a cesarean (hazard ratio, 3.38; 95% confidence interval, 1.09-10.49), but was imprecise among women who delivered vaginally (hazard ratio, 1.52; 95% confidence interval, 0.62-3.74). The risk of spontaneous preterm delivery among women with short second stage of labor (<30 minutes) in their first term pregnancy was 5.8% (n = 99; hazard ratio, 1.28; 95% confidence interval, 0.99-1.67).

CONCLUSION

The risk of spontaneous preterm delivery in the second pregnancy was increased in women with a prolonged (≥180 minutes) second stage in the first term pregnancy. This risk was even greater among women who were delivered by cesarean in the first pregnancy.

Comparison of Caesarean sections and instrumental deliveries at full cervical dilatation: a retrospective review

INTRODUCTION

This study aimed to compare instrumental vaginal deliveries (IDs) and Caesarean sections (CSs) performed at full cervical dilatation, including factors influencing delivery and differences in maternal and neonatal outcomes.

METHODS

A retrospective review was conducted of patients who experienced a prolonged second stage of labour at Singapore General Hospital from 2010 to 2012. A comparison between CS and ID was made through analysis of maternal/neonatal characteristics and peripartum outcomes.

RESULTS

Of 253 patients who required intervention for a prolonged second stage of labour, 71 (28.1%) underwent CS and 182 (71.9%) underwent ID. 5 (2.0%) of the patients who underwent CS had failed ID. Of the maternal characteristics considered, ethnicity was significantly different. Induction of labour and intrapartum epidural did not influence delivery type. 70.4% of CSs occurred outside office hours, compared with 52.7% of IDs (p = 0.011). CS patients experienced a longer second stage of labour (p < 0.001). Babies born via CS were heavier (p < 0.001), while the ID group had a higher proportion of occipitoanterior presentations (p < 0.001). Estimated maternal blood loss was higher with CSs (p < 0.001), but neonatal outcomes were similar.

CONCLUSION

More than one in four parturients requiring intervention for a prolonged second stage of labour underwent emergency CS. Low failed instrumentation rates and larger babies in the CS group suggest accurate diagnoses of cephalopelvic disproportion. The higher incidence of CS after hours suggests trainee reluctance to attempt ID. There were no clinically significant differences in maternal and neonatal morbidity.

Randomized controlled trial of prolonged second stage: extending the time limit vs usual guidelines

BACKGROUND

Guidelines for management of the second stage have been proposed since the 1800s and were created largely by expert opinion. Current retrospective data are mixed regarding differences in maternal and neonatal outcomes with a prolonged second stage. There are no randomized controlled trials that have evaluated whether extending the second stage of labor beyond current American College of Obstetricians and Gynecologists recommendations is beneficial.

OBJECTIVE

The purpose of this study was to evaluate whether extending the length of labor in nulliparous women with prolonged second stage affects the incidence of cesarean delivery and maternal and neonatal outcomes.

STUDY DESIGN

We conducted a randomized controlled trial of nulliparous women with singleton gestations at 36 0/7 to 41 6/7 weeks gestation who reached the American College of Obstetricians and Gynecologists definition of prolonged second stage of labor, which is 3 hours with epidural anesthesia or 2 hours without epidural anesthesia. Women were assigned randomly to extended labor for at least 1 additional hour, or to usual labor, which was defined as expedited delivery via cesarean or operative vaginal delivery. The exclusion criteria were intrauterine fetal death, planned cesarean delivery, age <18 years, and suspected major fetal anomaly. Primary outcome was incidence of cesarean delivery. Maternal and neonatal outcomes were compared secondarily. Statistical analysis was done by intention-to-treat.

RESULTS

Seventy-eight nulliparous women were assigned randomly. All of the women had epidural anesthesia. Maternal demographics were not significantly different. The incidence of cesarean delivery was 19.5% (n = 8/41 deliveries) in the extended labor group and 43.2% (n = 16/37 deliveries) in the usual labor group (relative risk, 0.45; 95% confidence interval, 0.22-0.93). The number needed-to-treat to prevent 1 cesarean delivery was 4.2. There were no statistically significant differences in maternal or neonatal morbidity outcomes.

CONCLUSION

Extending the length of labor in nulliparous women with singleton gestations, epidural anesthesia, and prolonged second stage decreased the incidence of cesarean delivery by slightly more than one-half, compared with usual guidelines. Maternal or neonatal morbidity were not statistically different between the groups; however, our study was underpowered to detect small, but potentially clinical important, differences.