Latent phase duration and associated outcomes: a contemporary, population-based observational study.

BACKGROUND: Little is known about the latent phase of labor, including whether its duration influences subsequent labor processes or birth outcomes. OBJECTIVE: This study aimed to describe the duration of the latent phase of labor from self-report of the onset of painful contractions to a cervical dilation of 5 cm in a large, Swedish population and evaluate the association between the duration of the latent phase of labor and perinatal processes and outcomes that occurred during the active phase of labor, second stage of labor, birth and immediately after delivery, stratified by parity. STUDY DESIGN: This was a population-based cohort study of 67,267 pregnancies with deliveries between 2008 and 2020 in the Stockholm-Gotland Regions, Sweden. Nulliparous and parous women without a history of cesarean delivery in spontaneous labor with a term (≥37 weeks of gestation), singleton, live, and vertex fetus without major malformations were included. Imputation was used if the notation of the end of the latent phase of labor (ie, cervical dilation of 5 cm) was missing in the partograph. Multivariable logistic regression was used to estimate the association with adjusted odds ratios and 95% confidence intervals, controlling for potential covariates. RESULTS: Including the time from painful contraction onset to a cervical dilation of 5 cm, the median durations of the latent phase of labor were 16.0 (interquartile range, 10.0-26.6) hours for nulliparous women and 9.4 (interquartile range, 5.9-15.3) hours for multiparous women. The durations of the latent phase of labor beyond the median were associated with increased odds of labor dystocia diagnosis during the first stage active phase or second stage of labor and interventions commonly associated with dystocia (amniotomy, oxytocin augmentation, epidural, and cesarean delivery). The duration of the latent phase of labor of ≥90th percentile vs less than the median in nulliparous women demonstrated an increased risk of adverse neonatal outcomes (Apgar score of <7 at 5 minutes and neonatal intensive care unit admission), chorioamnionitis, and fetal occiput posterior. In multiparous women, longer duration of the latent phase of labor was associated with an increased risk of neonatal intensive care unit admission and chorioamnionitis but was not associated with an Apgar score of <7 at 5 minutes. The duration of the latent phase of labor was not associated with additional markers of maternal risk. CONCLUSION: The duration of the latent phase of labor in nulliparous women was longer than that of multiparous women at each point of distribution. A longer duration of the latent phase of labor was associated with more frequent dystocia diagnoses and related interventions during the first stage active phase or second stage of labor, including cesarean delivery, nulliparous fetal occiput posterior position, chorioamnionitis, and markers of neonatal morbidity. More research is needed to identify potential mediating paths between the duration of the latent phase of labor and neonatal morbidity.

The evolution of the labor curve and its implications for clinical practice: the relationship between cervical dilation, station, and time during labor.

The assessment of labor progress is germane to every woman in labor. Two labor disorders-arrest of dilation and arrest of descent-are the primary indications for surgery in close to 50% of all intrapartum cesarean deliveries and are often contributing indications for cesarean deliveries for fetal heart rate abnormalities. Beginning in 1954, the assessment of labor progress was transformed by Friedman. He published a series of seminal works describing the relationship between cervical dilation, station of the presenting part, and time. He proposed nomenclature for the classification of labor disorders. Generations of obstetricians used this terminology and normal labor curves to determine expected rates of dilation and fetal descent and to decide when intervention was required. The analysis of labor progress presents many mathematical challenges. Clinical measurements of dilation and station are imprecise and prone to variation, especially for inexperienced observers. Many interrelated factors influence how the cervix dilates and how the fetus descends. There is substantial variability in when data collection begins and in the frequency of examinations. Statistical methods to account for these issues have advanced considerably in recent decades. In parallel, there is growing recognition among clinicians of the limitations of using time alone to assess progress in cervical dilation in labor. There is wide variation in the patterns of dilation over time and most labors do not follow an average dilation curve. Reliable assessment of labor progression is important because uncertainty leads to both over-use and under-use of cesarean delivery and neither of these extremes are desirable. This review traces the evolution of labor curves, describes how limitations are being addressed to reduce uncertainty and to improve the assessment of labor progression using modern statistical techniques and multi-dimensional data, and discusses the implications for obstetrical practice.

Sonographic evaluation of the fetal head position and attitude during labor.

Fetal malpresentation, malposition, and asynclitism are among the most common determinants of a protracted active phase of labor, arrest of dilatation during the first stage, and arrest of descent in the second stage. The diagnosis of these conditions is traditionally based on vaginal examination, which is subjective and poorly reproducible. Intrapartum sonography has been demonstrated to yield higher accuracy than vaginal examination in characterizing fetal malposition, and some guidelines endorse its use for the verification of the occiput position before performing an instrumental delivery. It is also useful for the objective diagnosis of the malpresentation or asynclitism of the fetal head. According to our experience, the sonographic assessment of the head position in labor is simple to perform also for clinicians with basic ultrasound skills, whereas the assessment of malpresentation and asynclitism warrants a higher level of expertise. When clinically appropriate, the fetal occiput position can be easily ascertained using transabdominal sonography combining the axial and the sagittal planes. With the transducer positioned on the maternal suprapubic region, the fetal head can be visualized, and landmarks including the fetal orbits, the midline, and the occiput itself with the cerebellum and the cervical spine (depending on the type of fetal position) can be demonstrated below the probe. Sinciput, brow, and face represent the 3 "classical" variants of cephalic malpresentation and are characterized by a progressively increasing degree of deflexion from vertex presentation. Transabdominal sonography has been recently suggested for the objective assessment of the fetal head attitude when a cephalic malpresentation is clinically suspected. Fetal attitude can be evaluated on the sagittal plane with either a subjective or an objective approach. Two different sonographic parameters such as the occiput-spine angle and the chin-chest angle have been recently described to quantify the degree of flexion in fetuses in non-occiput-posterior or occiput-posterior position, respectively. Finally, although clinical examination still represents the mainstay of diagnosis of asynclitism, the use of intrapartum sonography has been shown to confirm the digital findings. The sonographic diagnosis of asynclitism can be achieved in expert hands using a combination of transabdominal and transperineal sonography. At suprapubic sonography on the axial plane only, 1 orbit can be visualized (squint sign) while the sagittal suture appears anteriorly (posterior asynclitism) or posteriorly (anterior asynclitism) displaced. Eventually the transperineal approach does not allow the visualization of the cerebral midline on the axial plane if the probe is perpendicular to the fourchette. In this expert review we summarize the indications, technique, and clinical role of intrapartum sonographic evaluation of fetal head position and attitude.

The effect of maternal body mass index on duration of induced labor.

INTRODUCTION: Obese primiparous women with induction of labor are at high risk for a cesarean section. There are contradictory results regarding time in induced labor in relation to maternal body mass index (BMI). It is important to characterize the course of induced labor to prevent unnecessary cesarean section. We aimed to evaluate whether the duration of labor was associated with maternal BMI in primiparous women with induction of labor. MATERIAL AND METHODS: A national retrospective cohort study, including 15 259 primiparae with a single term pregnancy, admitted for induction of labor from January 2014 to August 2017. Data were obtained from the Swedish Pregnancy Registry. Cox regression analyses were used to illustrate the association between BMI and active labor and between BMI and time from admission until start of active labor. RESULTS: Duration of active labor was shorter in underweight women and prolonged in women with BMI ≥40 kg/m2 compared with women in other BMI classes, illustrated by Cox regression graphs (P < .001). The median durations of active labor in underweight women were 6.1 and 7.4 hours in women with BMI ≥40 kg/m2 . The time from admission until start of active labor increased with maternal BMI, illustrated by Cox regression graphs (P < .001) and the median duration increased from 12.9 hours in underweight women to 22.6 hours in women with BMI ≥40 kg/m2 . The cesarean section rate in active labor increased significantly with BMI (P < .001) from 7.4% in underweight women to 22.0% in women with BMI ≥40 kg/m2 . Obese and normal weight women had similar rates of spontaneous vaginal delivery (69.9% in the total study population). CONCLUSIONS: The duration of active labor was associated with maternal BMI for underweight women and women with BMI ≥40 kg/m2 . Although women with BMI ≥40 kg/m2 who reached the active phase of labor had the same chance for a spontaneous vaginal delivery as normal weight women, the duration of active labor and the cesarean section rate were increased. The time from admission until start of active labor increased successively with maternal BMI.

The association between longer durations of the latent phase of labor and subsequent perinatal processes and outcomes among midwifery patients.

BACKGROUND/OBJECTIVE: To evaluate the association between the duration of the latent phase of labor and subsequent processes and outcomes. METHODS: Secondary analysis of prospectively collected data among 1,189 women with low-risk pregnancies and spontaneous labor. RESULTS: Longer latent phase duration was associated with labor dystocia (eg, nulliparous ≥ mean [compared with < mean] aOR 3.95 [2.70-5.79]; multiparous ≥ mean [compared with < mean] aOR 5.45 [3.43-8.65]), interventions to ameliorate dystocia, and epidurals to cope or rest (eg, oxytocin augmentation: nulliparous > 80th% [compared with < 80th%] aOR 6.39 [4.04-10.12]; multiparous ≥ 80th% [compared with < 80th%] aOR 6.35 [3.79-10.64]). Longer latent phase duration was also associated with longer active phase and second stage. There were no associations between latent phase duration and risk for cesarean delivery or postpartum hemorrhage in a practice setting with relatively low rates of primary cesarean. Newborns born to multiparous women with latent phase of labor durations at and beyond the 80th% were more frequently admitted to the NICU (≥80th% [compared with < 80th%] aOR 2.7 [1.22-5.84]); however, two-thirds of these NICU admissions were likely for observation only. CONCLUSIONS: Longer duration of the spontaneous latent phase of labor among women with low-risk pregnancies may signal longer total labor processes, leading to an increase in diagnosis of dystocia, interventions to manage dystocia, and epidural use. Apart from multiparous neonatal NICU admission, no other maternal or child morbidity outcomes were elevated with longer duration of the latent phase of labor.

Maternal plasma leptin levels in relation to the duration of the active phase of labor.

INTRODUCTION: Obese women have increased leptin levels and longer duration of labor compared with normal-weight women. Leptin has an inhibitory effect on myometrial contractility in vitro. Our purpose was to examine whether maternal leptin levels in active labor were associated with the duration of the active phase of labor. MATERIAL AND METHODS: This prospective cohort study included 914 women. Maternal blood samples were collected in active labor. The plasma-leptin concentration was obtained using a direct sandwich-based ELISA. Bivariate and multiple linear regression analyses were used to study the association between leptin levels and the duration of labor. RESULTS: A 1 ng/mL increase in maternal plasma leptin was associated with a 0.015 hour increase in duration of labor (P < .007). This association was not statistically significant in the adjusted analyses nor when analyzing nulliparous and multiparous women separately. In women with spontaneous labor (n = 766) leptin levels were not associated with an increase in duration of labor in the adjusted analyses. CONCLUSIONS: There was no significant association between leptin levels and duration of the active phase of labor. Leptin in vivo might display a similar dose-response effect on myometrial contractility as demonstrated in in vitro studies. Future studies need to explore the association between leptin levels and time in labor in obese women with high leptin levels to evaluate a possible dose-response effect.

A predictive model for successfully inducing active labor among pregnant women: Combining cervical status assessment and clinical characteristics.

Objective: To develop a predictive model for successfully inducing active labor by using a combination of cervical status and maternal and fetal characteristics. Study design: A retrospective cohort study was conducted among pregnant women who underwent labor induction between January 2015 and December 2019. Successfully inducing active labor was defined as achieving a cervical dilation > 4 cm within 10 h after adequate uterine contractions. The medical data were extracted from the hospital database; statistical analyses were performed using a logistic regression model to identify the predictors associated with the successful induction of labor. The receiver operating characteristic (ROC) curve and area under the curve (AUC) were used to assess the accuracy of the model. Results: In total, 1448 pregnant women were enrolled; 960 (66.3 %) achieved successful induction of active labor. Multivariate analysis revealed that maternal age, parity, body mass index, oligohydramnios, premature rupture of membranes, fetal sex, dilation, station, and consistency were significant factors associated with successful labor induction. The ROC curve of the logistic regression model had an AUC of 0.7736. For the validated score system to predict the probability of success, we found that a total score > 60 has a 73.0 % (95 % CI 59.0-83.5) probability of successful induction of labor into the active phase stage within 10 h. Conclusions: The predictive model for successfully achieving active labor using the combination of cervical status and maternal and fetal characteristics had good predictive ability.

Applying a physiotherapy protocol to women during the active phase of labor improves obstetrical outcomes: a randomized clinical trial.

BACKGROUND: Labor is a physiological process triggered by mechanical and hormonal events that promote uterine contractions to expel the fetus. OBJECTIVE: This study aimed to evaluate the effectiveness of a nonpharmacologic childbirth care protocol in women in the active phase of labor in improving obstetrical and perinatal outcomes. STUDY DESIGN: This was a randomized trial with concealed allocation, assessor blinding, and intention-to-treat analysis. A total of 80 low-risk primigravida women at the end of pregnancy admitted at the beginning of the active phase of labor participated in the study. The participants were divided into an experimental group (n=40) and a control group (n=40). Women in the experimental group received 4 interventions: ambulation at 4 to 6 cm of cervical dilation, alternation of maternal postures, transcutaneous electrical nerve stimulation at 6 to 7 cm, and a warm shower bath at >7 cm. The control group received only routine obstetrical care during labor. The parturient could request pharmacologic analgesia at any time during the study. The main outcome measures were the duration of the active phase of the first stage of labor, the duration of the expulsive phase of labor, and the prevalence of labor dystocia as assessed by the partograph. The researchers collected other maternal and neonatal data from official birth records. RESULTS: The parturients who received the nonpharmacologic protocol had a shorter active phase of the first stage of labor (444 minutes in the control group and 373 minutes in the experimental group; P=.02), presented rupture of membranes later in labor (7 cm in the control group and 8 cm in the experimental group; P<.01), requested pharmacologic analgesia with more significant cervical dilation (5 cm in the control group and 8 cm in the experimental group; P<.01), requested fewer additional doses of analgesics, and had lower labor dystocia rates than the patients in the control group. In addition, there was no difference in other maternal and perinatal variables between the control group and the experimental group. CONCLUSION: The implementation of a sequential nonpharmacologic protocol composed of ambulation, transcutaneous electrical nerve stimulation with change of upright positions, and warm shower bath has the potential to reduce labor pain, as reflected in decreased and delayed use of pharmacologic analgesia and reduced duration of the active phase of labor and dystocia rates. Maternity hospitals should provide this protocol, and women should be encouraged to request this childbirth care protocol.

Continuous oxytocin versus intermittent oxytocin for induction of labor: a randomized study.

Objective: To assess whether intermittent usage of oxytocin infusion increases the duration of the active phase of labor and reduces maternal and neonatal complications or not.Materials and Methods: A prospective randomized controlled study was conducted of 200 consenting women with singleton pregnancy in the vertex position undergoing labor induction or augmentation at the Zeynep Kamil Maternity and Children's Training and Research Hospital. Participants with cervical dilation of 3 cm were randomized to either continued or intermittent oxytocin infusion when cervical dilation reached 5 cm. The primary outcome measures were the duration of the active phase of labor, defined as the period of labor from 5 cm of cervical dilation to vaginal delivery. Secondary outcomes were the duration of oxytocin infusion, mode of delivery, hyperstimulation, abnormalities in fetal heart rate, perineal tears, and neonatal outcomes.Results: The median duration of the active phase for the women with a vaginal delivery was longer in the intermittent oxytocin group than the continued oxytocin group, but it was not statistically significant (median, 6.91 vs. 7.58 h, p = .37). There was a significant difference in the duration of oxytocin infusion (median, 12.38 h in the intermittent group vs. 15.79 h in the continued group, p = .005). The incidence of uterine hyperstimulation was significantly greater in the continued group (21.1%) than the intermittent oxytocin group (3.8%) (p=.001).Conclusions: Intermittent usage of oxytocin infusion seems to make labor less complicated without lengthening duration of labor.

Dehiscence of cesarean section scar during pregnancy and delivery - risk factors.

OBJECTIVE: We wanted to identify risk factors for dehiscence of cesarean section (CS) scars in patients undergoing repeated cesarean section. MATERIAL AND METHODS: This was a retrospective case-control study over a 3-year period in our medical center (2011-2014), comparing women who had repeated CS without complications and women diagnosed with dehiscence. Data were collected from medical records and the groups were compared for demographic and obstetrical data. RESULTS: Dehiscence was identified in 27 women, while 54 women without dehiscence were the control group. Statistically significant differences were found in the need for augmentation, the number of previous cesarean sections, cesarean section in the active phase of labor and length of hospitalization. DISCUSSION: The need for augmentation of labor, CS in the nonactive stage and more than one cesarean section, all increased the risk of dehiscence. There was no association between dehiscence and scar pain, time elapsed since the previous cesarean section, the method of wound closure or fever.

The Effect of Auriculotherapy on Labor Pain, Length of Active Phase and Episiotomy Rate Among Reproductive Aged Women.

Objective: This study aimed to evaluate the effect of auriculotherapy on labor pain, the length of the active phase, and episiotomy rate among reproductive aged Iranian women. Materials and methods: In this study, 80 women were assigned to two groups: auriculotherapy (n = 40) and control group (n = 40). Auriculotherapy was performed in the earlobe in the Zero, Shen Men, Uterus, Pelvic, Abdomen, Spleen, External genitalia, and Master cerebral regions in the cervix dilation of 4, 6, and 8 cm between uterine contractions. The control group received routine hospital care. The labor pain, duration of the active phase, and rate of episiotomy were assessed in two groups. The independent t- test and chi-square were used for statistical purposes. Results: The mean of labor pain during the active phase was 7.56 ± 0.83 in the auriculotherapy group and 8.43 ± 0.69 in the control group (p < 0.001). The length of active phase was significantly lower in the auriculotherapy than that in the control group (176.2 ± 1 min vs. 342.8±87.2 min, p < 0.001). The rate of normal vaginal delivery (without an episiotomy or perineal tears) was significantly higher in the auriculotherapy group than that in the control group (50% vs. 2.5%, p < 0.001). Conclusion: Auriculotherapy is safe, cost effective and devoid of side effects to reduce the labour pain, length of the active phase and the rate of episiotomy in nulliparous women. This method can be considered as a complementary medicine in labour.

Effect of oxytocin discontinuation during the active phase of labor.

OBJECTIVE: To observe the progression of labor when oxytocin use is limited to the onset of the active stage of labor. METHODS: A randomized, prospective controlled study was performed to address the issue of oxytocin infusion after the onset of active labor in 140 patients. In the study group, infusion of oxytocin was discontinued at the onset of the active phase of labor, which was accepted as a cervical dilatation of 5 cm. In the control group, incremental oxytocin infusion was administered until 5 cm cervical dilatation, and then was maintained at the same level until delivery. RESULTS: The primary outcome variable was duration from the beginning of the active phase to delivery. In the study group, the duration of the active phase of labor was about 30 min longer than in the control group and this difference was significant. The secondary outcomes of the study were maternal-fetal complications of oxytocin and in both groups there were no significant differences. CONCLUSION: It is not reasonable to discontinue oxytocin infusion at the beginning of active labor. Nevertheless, for an accurate conclusion expanded investigations are needed.

Effect of intravenous hyoscine-N-butyl bromide on active phase of labor progress: a randomized double blind placebo controlled trial.

INTRODUCTION: Appropriate cervical dilatation and effacement are essential for the progression of labor. With the active management of labor, number of cesarean deliveries reduces and the duration of labor shortens. Cervical dilatation can be facilitated by mechanical, pharmacological and non-pharmacologic methods. Cervix is richly supplied by autonomic nerves, which may play a role in the dilatation of cervix. Hyoscine-N-butylbromide (HBB) is a muscarinic antagonist and acts as a cervical spasmolytic agent. After intravenous administration it is rapidly distributed into the tissues. We aimed to study the effects and safety of a single dose 20 mg HBB injection during the active phase of labor in both primi- and multigravid women. MATERIALS AND METHOD: A randomized, double-blinded, controlled trial, with healthy primigravid and multigravid women in spontaneous labor at term was considered in this study. Once the active phase of labor was achieved, either a single dose of 20 mg (1 mL) of HBB or placebo (1 mL saline) was given intravenously. RESULTS: The mean duration of the first stage of labor was 191.1 ± 43.06 min in the primigravid patients of the HBB group, while it was 248.2 ± 66.1 min in the placebo group, a statistically significant difference of 57 min (p < 0.001). The mean duration of the first stage of labor was 170.1 ± 50.8 min in the multigravid patients of the HBB group, while it was 224.06 ± 53.7 min in the placebo group (difference of 54 min, p < 0.001). The mean duration of the first stage of labor was significantly different both for multigravida and primigravid patients. There was no significant change in the times for the second and third stages of labor. There were no significant differences in terms of APGAR scores noted at 1 and 5 min, prepartum and postpartum hemoglobin levels and birth weight. No adverse maternal and fetal effects were observed in both HBB and placebo groups. CONCLUSION: A single dose of 20 mg intravenous HBB is effective and safe in shortening the duration of the first stage of labor without any adverse effects on fetus and mother.

Maternal body mass index and duration of labor.

OBJECTIVE: To evaluate whether the duration of the active phase of labor is associated with maternal body mass index (BMI), in nulliparous women with spontaneous onset of labor. STUDY DESIGN: Historical prospective cohort study including 63,829 nulliparous women with a singleton pregnancy and a spontaneous onset of labor, who delivered between January 1, 1995 and December 31, 2009. Data were collected from the Perinatal Revision South registry, a regional perinatal database in Southern Sweden. Women were categorized into six classes of BMI. Overweight and obese women were compared to normal weight women regarding duration of active labor. Adjustments were made for year of delivery, maternal age and infant birth weight. RESULTS: The median duration of labor was significantly longer in obese women (class I obesity (BMI 30-34.9) = 9.1h, class II obesity (BMI 35-39.9) = 9.2h and class III obesity (BMI > 40) = 9.8h) compared to normal-weight women (BMI 18.5-24.9) = 8.8h (p < 0.001). The risk of labor lasting more than 12h increased with increasing maternal BMI: OR 1.04 (1.01-1.06) (OR per 5-units BMI-increase).The risk of labor lasting more than 12h or emergency cesarean section within 12h, compared to vaginal deliveries within 12h, increased with increasing maternal BMI. Duration of the second stage of labor was significantly shorter in obese women: in class III obesity the median value was 0.45 h compared to normal weight women, 0.55 h (p < 0.001). CONCLUSION: In nulliparous women with a spontaneous onset of labor, duration of the active phase of labor increased significantly with increasing maternal BMI. Once obese women reach the second stage they deliver more quickly than normal weight women, which implies that the risk of prolonged labor is restricted to the first stage of labor. It is clinically important to consider the prolonged first stage of labor in obese women, for example when diagnosing first stage labor arrest, in order to optimize management of this rapidly growing at-risk group of women. Thus, it might be reasonable to adapt the considered upper limit for duration of labor, according to maternal BMI.