Just go with your body? A conversation analytic study of the transition from first to second stage of labor in UK midwife-led care.

BACKGROUND: The transition from first to second stage of labor is poorly understood. While the onset of second stage is defined by cervical measurement, dilation cannot be directly sensed or externally observed. Thus, uncertainty exists when women report pushing urges before dilation is confirmed. This study aimed to explore how sensations of pushing and uncertainty over progress are interactionally managed. METHODS: We audio/video recorded the labors of 37 women in two midwife-led units in England. Our analysis focused on a subset of 28 recordings that featured discussion of transition from first to second stage of labor. The interactions between midwives, laboring women and their birth partners were transcribed and analyzed using conversation analysis. RESULTS: We identified a 'pushing until proven otherwise' rule granting temporary, contingent authority to bodily urges to push while tracking progress over time. Specifically, midwives supported reported pushing sensations without insisting on examinations. Caution was occasionally expressed in distinguishing between irresistible and forced pushing. Across multiple contractions, midwives watched and waited for alignment of sensations with signs of descent. Where signs of progress were absent over time, examinations were treated as clinically indicated. DISCUSSION: Thus, a complex interplay of women's sensations and midwifery expertise produced care. Compared to past research, our analysis demonstrates increased validation of embodied experience in contemporary midwife-led practice. However, uncertainty still requires navigation through collaborative work. We evidence how this navigation is accomplished in real-time interactions.

Cesarean section at full dilatation in the first birth is not associated with an increased risk of subsequent miscarriage: A historical cohort study.

INTRODUCTION: Cesarean section at full dilatation has been associated with an increased risk of subsequent preterm birth. We hypothesized that there may be an increased risk of miscarriage in pregnancies that follow cesarean section at full dilatation. This study aimed to determine if a first-term (≥37 weeks) cesarean section at full dilatation is associated with an increased risk of miscarriage in the next pregnancy. MATERIAL AND METHODS: A historical cohort study was conducted using routinely collected hospital data within the Aberdeen Maternity and Neonatal Databank (AMND). The population included were women who had a first-term birth and who had a second birth recorded within the AMND. Logistic and multinomial regression was used to determine any association with miscarriage at any gestation and for early (<13 weeks gestation) and late (13-23 + 6 weeks gestation) miscarriage, with cesarean section at full dilatation defined as the exposure. Miscarriage in the second pregnancy (spontaneous loss of intrauterine pregnancy prior to 24 weeks gestation) was the primary outcome. RESULTS: In total, 33 452 women were included. Women who had a first cesarean section at full dilatation were no more likely to have a miscarriage at any gestation than women with all other modes of first birth (including all vaginal births, planned CS, and the first stage of labor (<10 cm dilated CS)) [adjusted OR 0.84 (0.66-1.08); p = 0.18]. There was no association with early or late miscarriage after a CSfd, though the sample size for late miscarriage was small. CONCLUSIONS: This is the first observational study to investigate the risk of miscarriage following first-term CSfd. We found no association between miscarriage at any gestation following a first-term CSfd compared to all other modes of first birth.

Prolonged second stage of labor and risk of postpartum hemorrhage in nullipara with epidural anesthesia and vaginal delivery: A cohort study with propensity score analysis.

OBJECTIVE: To conduct an analysis using propensity score methods, exploring the association between a prolonged second stage (>3 h) and the risk of postpartum hemorrhage (PPH) in a diverse population. METHODS: We conducted a prospective cohort study involving nullipara with epidural anesthesia and vaginal delivery, aged ≥18 years, presenting cephalically, and with a gestational age (GA) of ≥24 weeks at a tertiary maternity hospital in China (chictr.org.cn identifier: ChiCTR2200063094). Women undergoing emergency cesarean section in labor were excluded. The primary outcome was PPH, with secondary outcomes including severe postpartum hemorrhage and blood transfusion. We employed propensity score overlap weighting to analyze the association between prolonged second stage labor and PPH. RESULTS: The study included 3643 nullipara with epidural anesthesia, comprising 77 with a second stage of labor >3 h and 3566 with a second stage ≤3 h. Utilizing propensity score overlap weighting, there were no significant differences observed between the two groups regarding the risk of PPH (29.87% in >3 h group vs 17.64% in ≤3 h group; weighted odds ratio 1.01; 95% CI: 0.51-2.02). Subgroup interaction tests for PPH were not significant for assisted vaginal delivery, induction of labor, macrosomia, third-/fourth-degree perineal laceration, GA >41 weeks, twin pregnancies, episiotomy and GA >37 weeks. Sensitivity analysis did not reveal significant differences. CONCLUSION: This study did not find evidence supporting an increased risk of PPH associated with a second stage of labor lasting >3 h in our population, providing additional evidence for clinical practice.

Understanding the dynamics of Meloidogyne incognita infestation in pomegranate orchards of Himachal Pradesh, India (year 2018, 2019 and 2021) and its management strategies.

This study investigates the prevalence and dynamics of pomegranate wilt disease induced by Meloidogyne incognita across the Kullu, Mandi and Solan districts of Himachal Pradesh (India), revealed notable spatial and temporal variations in nematode populations and galling severity across the regions. The highest average nematode infestation of 9.25 % was observed at Nauni with highest counts of average second-stage juvenile (J2) larvae (449 larvae per 100 cc of soil) followed by Hurla (Kullu) with 7.42 % infestation. Correlation analysis reveals a strong positive relationship between larval population and galling severity suggesting a potential link between nematode levels and plant damage. Common disease symptoms were leaf size reduction, yellowing and gradual decline of pomegranate plants, often observed in patches within orchards. Microscopic identification revealed distinctive pear-shaped body of mature females while J2 larvae displayed vermiform shapes and the associated species of M. incognita was confirmed through examination of the perineal pattern. Pathogenicity test reveals initiation of leaf yellowing symptom after 45 days of inoculation of larval suspension and root galling was observed after 60 days onward followed by plant decline under greenhouse conditions. Results from pot and field experiments demonstrated the efficacy of Fluopyram and Fluensulfone in reducing nematode populations and galling severity. Treatment with drenching of Fluopyram at the rate of 2 ml/L reduced 98.56 % larvae under field and 99.00 % larvae/100 cc soil under pot conditions. Statistical analysis (paired t-test and MANOVA) confirms significant differences in galling severity and larval population before and after drenching. The study also underscores the importance of weed management in disease mitigation as several weed species (Chenopodium album and Solanum nigrum) were identified as potential reservoirs for M. incognita in infested pomegranate plant basin. This investigation contributes to the advancement of management practices for pomegranate cultivation that addresses both nematode and weed infestations ultimately enhancing crop resilience and productivity.

Circumferential Vaginal Tear During the Cesarean Section: A Complication of Vaginal Hand Assistance in a Deeply Impacted Fetal Head.

We present the case of a 29-year-old, G2P1+0 pregnant woman who was unbooked and presented to the emergency room at 36+5 weeks gestation with complaints of leaking liquor, labour pains, vaginal bleeding and raised blood pressure. Her history revealed previous vaginal delivery and index pregnancy complicated with obstetric cholestasis, pre-eclampsia, and fetal growth restriction. During her hospital course, the patient underwent an emergency cesarean section due to uncontrolled blood pressure and pathological cardiotocograph (CTG) revealing a deeply impacted fetal head intraoperatively and necessitating an inverted T incision on the uterus. Although the newborn was delivered successfully, a full-thickness circumferential tear in the vaginal vault was discovered, requiring immediate surgical repair with the involvement of a urologist. The patient experienced postoperative complications related to pre-eclampsia and sepsis but was eventually discharged in stable condition. This case highlights the importance of prompt diagnosis and management of obstetric emergencies especially in the case of deeply impacted fetal head, and the need for a multidisciplinary approach to address complications such as vaginal tears during cesarean sections due to vaginal assistance in delivering the baby.

Modified Roll Envelope Technique Combined With Apically Repositioned Flap (MRARF) for Peri-Implant Soft Tissue Augmentation-A Case Series.

In the present case series, we performed implant surgery using a modified roll envelope technique and an apically repositioned flap (MRARF). To improve patients' peri-implant soft tissue phenotypes, they underwent dental implantation following the buccal contour concavities, inadequate keratinized tissue width, and soft tissue thickness simultaneously. This case series includes 4 patients treated between July 2021 and February 2022 who received dental implants and guided bone regeneration treatment 6 months earlier and were to be taken up for second-stage surgery. They were eligible for the MRARF technique if each implant site showed a labial and buccal deficiency and a reduced keratinized mucosa width than the adjacent teeth. Sutures were removed 2 weeks after surgery, and a provisional restoration was delivered. A final impression was taken at 6 weeks to produce the definitive implant-supported restoration. All surgery sites healed uneventfully, and no postoperative pain or excessive swelling was reported. The modified flap design allowed for increasing the width and thickness of keratinized mucosa with a minimally invasive technique. A harmonious color, texture, and mucogingival junction position that matched the surrounding tissue and adjacent teeth was achieved, and all patients were satisfied with the final results. MRARF at second-stage implant surgery could obtain satisfactory results regarding vertical and horizontal aesthetic gingival contours and an adequate width and thickness of keratinized mucosa around the implants.

Inconsistent definitions of prolonged labor in international literature: a scoping review.

Objective: Prolonged labor is the commonest indication for intrapartum cesarean section, but definitions are inconsistent and some common definitions were recently found to overestimate the speed of physiological labor. The objective of this review is to establish an overview of synonyms and definitions used in the literature for prolonged labor, separated into first and second stages, and establish types of definitions used. Data sources: A systematic search was conducted in PubMed, Embase, Web of Science, Cochrane Library, Emcare, and Academic Search Premier. Study eligibility criteria: All articles in English that (1) attempted to define prolonged labor, (2) included a definition of prolonged labor, or (3) included any synonym for prolonged labor, were included. Methods: Data on study design, year of publication, country or region of origin, synonyms used, definition of prolonged first and/or second stage, and origin of provided definition (if not primarily established by the study) were collected into a database. Results: In total, 3402 abstracts and 536 full-text papers were screened, and 232 papers were included. Our search established 53 synonyms for prolonged labor. Forty-three studies defined prolonged labor and 189 studies adopted a definition of prolonged labor. Definitions for prolonged first stage of labor were categorized into: time-based (n=14), progress-based (n=12), clinician-based (n=5), or outcome-based (n=4). For the 33 studies defining prolonged second stage, the majority of definitions (n=25) were time-based, either based on total duration or duration of no descent of the presenting part. Conclusions: Despite efforts to arrive at uniform labor curves, there is still little uniformity in definitions of prolonged labor. Consensus on which definition to use is called for, in order to safely and respectfully allow physiological labor progress, ensure timely management, and assess and compare incidence of prolonged labor between settings.

Improving management of first and second stages of labour in low- and middle-income countries.

Labour care must balance aspirations of parents with vigilance for unanticipated calamities. The 'on-site midwife-led primary care birth unit' facilitates this. The World Health Organization have replaced the traditional partograph with the 'Labour Care Guide'. An implementation project in Botswana included the mnemonic COPE: Companion, Oral fluids, Pain relief and Eliminate the supine position. The Parto-Ma project in Tanzania used guidelines, training and support to improve childbirth outcomes. We list labour practices supported by recent evidence, and highlight new developments. Foetal macrosomia increases risk but mistaken diagnosis increases caesarean births. Obstructed labour is a complex clinical diagnosis, and is difficult to predict. For shoulder dystocia prioritise delivery of the posterior shoulder, facilitated if needed by posterior axilla sling traction. 'Extended balloon labour induction' with two or three Foley catheters side by side, may reduce risks associated with uterine stimulants. Bedside ultrasound may facilitate the diagnosis of cephalic malpositions and malpresentations.

Effects of perineal massage at different stages on perineal and postpartum pelvic floor function in primiparous women: a systematic review and meta-analysis.

BACKGROUND: Perineal massage, as a preventive intervention, has been shown to reduce the risk of perineal injuries and may have a positive impact on pelvic floor function in the early postpartum period. However, there is still debate concerning the best period to apply perineal massage, which is either antenatal or in the second stage of labor, as well as its safety and effectiveness. Meta-analysis was used to evaluate the effect of implementing perineal massage in antenatal versus the second stage of labor on the prevention of perineal injuries during labor and early postpartum pelvic floor function in primiparous women. METHODS: We searched nine different electronic databases from inception to April 16, 2024. The randomized controlled trials (RCTs) we included assessed the effects of antenatal and second-stage labor perineal massage in primiparous women. All data were analyzed with Revman 5.3, Stata Statistical Software, and Risk of Bias 2 was used to assess the risk of bias. Subgroup analyses were performed based on the different periods of perineal massage. The primary outcomes were the incidence of perineal integrity and perineal injury. Secondary outcomes were perineal pain, duration of the second stage of labor, postpartum hemorrhage, urinary incontinence, fecal incontinence, and flatus incontinence. RESULTS: This review comprised a total of 10 studies that covered 1057 primigravid women. The results of the analysis showed that perineal massage during the second stage of labor reduced the perineal pain of primigravid women in the immediate postpartum period compared to the antenatal period, with a statistical value of (MD = -2.29, 95% CI [-2.53, -2.05], P < 0.001). Additionally, only the antenatal stage reported that perineal massage reduced fecal incontinence (P = 0.04) and flatus incontinence (P = 0.01) in primiparous women at three months postpartum, but had no significant effect on urinary incontinence in primiparous women at three months postpartum (P = 0.80). CONCLUSIONS: Reducing perineal injuries in primiparous women can be achieved by providing perineal massage both antenatally and during the second stage of labor. Pelvic floor function is improved in the postnatal phase by perineal massage during the antenatal stage. TRIAL REGISTRATION: CRD42023415996 (PROSPERO).

Passive second stage of labor: Does a fourth hour increase maternal morbidity in nulliparous patients at term with epidural?

OBJECTIVES: Prolonging the passive second stage of labor could increase vaginal birth rate, but the data concerning maternal and fetal morbidity are contradictory. The French guidelines did not specify a maximum duration of the passive second stage. Our objective was to assess if allowing a 4th hour after full dilatation before pushing increased maternal morbidity, compared to 3 h after full dilatation. STUDY DESIGN: This single-center, retrospective, observational cohort study took place from January 1-December 31, 2020, in a tertiary maternity unit. All consecutive term nulliparous women who delivered under epidural anesthesia and without pathological fetal heart rate and reaching a second-stage passive phase of labor lasting at least 3 h were included. We compared 2 groups according to the duration of the passive second stage: "3-hour group" and "4-hour group". In the "3-hour group," featuring a second-stage passive phase of up to 3 h, pushing is initiated for favorable conditions, while a cesarean section is performed if conditions are deemed unfavorable. In the "4-hour group", obstetric conditions not justifying immediate pushing after three hours, and the obstetric team believed that an additional hour of expectant management could lead to a successful vaginal delivery. The principal endpoint was a composite criterion of maternal morbidity including obstetric anal sphincter injuries, postpartum hemorrhage, transfusion and intrauterine infection. RESULTS: We included 111 patients in the "4-hour group" and 349 in the "3-hour group". Composite maternal morbidity did not increase in the "4-hour group" compared to the "3-hour group" (21 (18.9 %) versus 61 (17.5 %); p = 0.73). Neonatal morbidity was similar between the two groups. In the "4-hour group, 91 (82 %) patients had vaginal deliveries", 62 (55,9 %) by spontaneous vaginal delivery and 29 (26,1 %) with instrumental assistance. CONCLUSION: For selected patients, waiting for 4 h at full dilation can be beneficial due to the high rate of vaginal delivery and low incidence of maternal and fetal complications.

Prediction of spontaneous vaginal delivery in the prolonged second stage using the delta angle of progression.

BACKGROUND: It is clinically challenging to determine when to intervene in the prolonged second stage. Although individualized prediction of spontaneous vaginal delivery is crucial to avoid maternal and neonatal complications associated with operative deliveries, the approach has not been fully established. OBJECTIVE: We aimed to evaluate the predictability of spontaneous vaginal delivery using the difference in angle of progression between pushing and rest, delta angle of progression, to establish a novel method to predict spontaneous vaginal delivery during the prolonged second stage in nulliparous women with epidural anesthesia. STUDY DESIGN: We retrospectively analyzed deliveries of nulliparous women with epidural anesthesia between September 2018 and October 2023. Women were included if their delta angle of progression during the second stage was available. Operative deliveries were defined as the cases that required forceps, vacuum, and cesarean deliveries due to labor arrest. Women requiring operative deliveries due to fetal and maternal concerns, or women with fetal occiput posterior presentation were excluded. The second stage was stratified into the prolonged second stage, the period after 3 hours in the second stage, and the normal second stage, the period from the beginning until the third hour of the second stage. The association of the delta angle of the progression measured during each stage with spontaneous vaginal delivery and operative deliveries was investigated. Furthermore, the predictability of spontaneous vaginal delivery was evaluated by combining the delta and rest angle of progression. RESULTS: A total of 129 women were eligible for analysis. The delta angle of progression measured during the prolonged second stage and normal second stage were significantly larger in women who achieved spontaneous vaginal delivery compared to operative deliveries (p<.001 and p<.05, respectively). During the prolonged second stage, a cutoff of 18.8 derived from the receiver operative characteristic curves in the context of the delta angle of progression predicted the possibility of spontaneous vaginal delivery (sensitivity, 81.8%; specificity, 60.0%; AUC, 0.76). Combining the rest angle of progression (>140) and delta angle of progression (>18.8) also provided quantitative prediction of spontaneous vaginal delivery (sensitivity, 86.7%; specificity, 70.0%; AUC, 0.80). CONCLUSION: The delta angle of progression alone or in combination with the rest angle of progression can be used to predict spontaneous vaginal delivery in the second stage in nulliparous women with epidural anesthesia. Quantitative analysis of the effect of pushing using the delta angle of progression provides an objective guide to assist with an assessment of labor dystocia in the prolonged second stage on an individualized basis, which may optimize labor management in the prolonged second stage by reducing neonatal and maternal complications related to unnecessary operative deliveries and prolonged second stage of labor.

Correlative analysis of different treatments of persistent occipitotransverse position on the outcome for mother and infant.

OBJECTIVE: To explore the clinical feasibility of different treatment methods for persistent occipitotransverse position and the influence on maternal and infant complications. METHOD: During the trial of vaginal delivery from April 2020 to March 2023 in our hospital, the cervix was fully dilated and the presentation was located at +2 station. Ninety-six pregnant women with fetal presentation at +4 station, occipitotransverse fetal position, maternal complications, abnormalities in the second stage of labor, and or fetal distress were divided into two groups: 65 patients with Kielland forceps vaginal delivery and 31 patients underwent emergency cesarean section. The delivery time, vaginal laceration rate, postpartum blood loss volume, puerperal infection rate, neonatal birth injury rate, and neonatal 1 min Apgar scores were analyzed. RESULTS: The delivery outcomes and maternal and neonatal complications of 96 pregnant women were analyzed: the application of Kielland forceps delivery time was shorter, while the vaginal laceration rate, postpartum hemorrhage, puerperal infection rate were significantly lower than that of patients undergoing emergency cesarean section and the neonatal 1 min Apgar score was higher than that of emergency cesarean section group (p < 0.05). CONCLUSION: It was clinically appropriate to use Kielland forceps in vaginal delivery when the persistent occipitotransverse position was present and delivery needed to be expediated. Use of Kielland forceps can shorten the delivery time, improve the success rate of vaginal delivery and reduce the complications of mothers and infants.

Midwives' experiences of professional learning when practicing collegial midwifery assistance during the active second stage of labour: data from the oneplus trial.

BACKGROUND: Learning is a lifelong process and the workplace is an essential arena for professional learning. Workplace learning is particularly relevant for midwives as essential knowledge and skills are gained through clinical work. A clinical practice known as 'Collegial Midwifery Assistance' (CMA), which involves two midwives being present during the active second stage of labour, was found to reduce severe perineal trauma by 30% in the Oneplus trial. Research regarding learning associated with CMA, however, is lacking. The aim was to investigate learning experiences of primary and second midwives with varying levels of work experience when practicing CMA, and to further explore possible factors that influence their learning. METHODS: The study uses an observational design to analyse data from the Oneplus trial. Descriptive statistics and proportions were calculated with 95% confidence intervals. Stratified univariable and multivariable logistic regression analysis were performed. RESULTS: A total of 1430 births performed with CMA were included in the study. Less experienced primary midwives reported professional learning to a higher degree (< 2 years, 76%) than the more experienced (> 20 years, 22%). A similar but less pronounced pattern was seen for the second midwives. Duration of the intervention ≥ 15 min improved learning across groups, especially for the least experienced primary midwives. The colleague's level of experience was found to be of importance for primary midwives with less than five years' work experience, whereas for second midwives it was also important in their mid to late career. Reciprocal feedback had more impact on learning for the primary midwife than the second midwife. CONCLUSIONS: The study provides evidence that CMA has the potential to contribute with professional learning both for primary and second midwives, for all levels of work experience. We found that factors such as the colleague's work experience, the duration of CMA and reciprocal feedback influenced learning, but the importance of these factors were different for the primary and second midwife and varied depending on the level of work experience. The findings may have implications for future implementation of CMA and can be used to guide the practice.

[Update on the management modalities of expulsive efforts during childbirth]. / Mise au point sur les modalités de gestion des efforts expulsifs lors de l'accouchement.

The second stage of labour includes both the passive and active stages, involving expulsive efforts. The management of this phase of labour aims to minimise the maternal and neonatal complications that could be associated with a prolonged active2nd stage, but also to limit medical interventions. On the maternal side, prolonged duration of expulsive effort appears to be correlated with increased postpartum haemorrhage, perineal injury and, in the long term, urinary and anal incontinence. From a neonatal viewpoint, expulsive efforts carry risks of neonatal acidosis, asphyxia, admission to the neonatal intensive care unit and trauma. Optimal management of expulsive efforts involves several strategies. Various aspects need to be addressed in order to optimise this management, including the timing of the start of expulsive efforts, comparing immediate pushing with delayed pushing, and the duration of expulsive efforts. In addition, it is important to examine the different pushing modalities, whether intense or moderate, using open or closed-glottis pushing, as well as the maternal position during pushing. According to the current literature, no specific technique or predefined duration appears to reduce the risk of neonatal or maternal complications. It therefore seems essential to adopt an individualised approach for each woman, placing her at the centre of the care and decision-making process, in order to take account of her preferences during childbirth.

On the uncertainty quantification of the active uterine contraction during the second stage of labor simulation.

Uterine contractions in the myometrium occur at multiple scales, spanning both organ and cellular levels. This complex biological process plays an essential role in the fetus delivery during the second stage of labor. Several finite element models of active uterine contractions have already been developed to simulate the descent of the fetus through the birth canal. However, the developed models suffer severe reliability issues due to the uncertain parameters. In this context, the present study aimed to perform the uncertainty quantification (UQ) of the active uterine contraction simulation to advance our understanding of pregnancy mechanisms with more reliable indicators. A uterus model with and without fetus was developed integrating a transversely isotropic Mooney-Rivlin material with two distinct fiber orientation architectures. Different contraction patterns with complex boundary conditions were designed and applied. A global sensitivity study was performed to select the most valuable parameters for the uncertainty quantification (UQ) process using a copula-based Monte Carlo method. As results, four critical material parameters ( C 1 , C 2 , K , Ca 0 ) of the active uterine contraction model were identified and used for the UQ process. The stress distribution on the uterus during the fetus descent, considering first and second fiber orientation families, ranged from 0.144 to 1.234 MPa and 0.044 to 1.619 MPa, respectively. The simulation outcomes revealed also the segment-specific contraction pattern of the uterus tissue. The present study quantified, for the first time, the effect of uncertain parameters of the complex constitutive model of the active uterine contraction on the fetus descent process. As perspectives, a full maternal pelvis model will be coupled with reinforcement learning to automatically identify the delivery mechanism behind the cardinal movements of the fetus during the active expulsion process.

Parturition at term: induction, second and third stages of labor, and optimal management of life-threatening complications-hemorrhage, infection, and uterine rupture.

Childbirth is a defining moment in anyone's life, and it occurs 140 million times per year. Largely a physiologic process, parturition does come with risks; one mother dies every two minutes. These deaths occur mostly among healthy women, and many are considered preventable. For each death, 20 to 30 mothers experience complications that compromise their short- and long-term health. The risk of birth extends to the newborn, and, in 2020, 2.4 million neonates died, 25% in the first day of life. Hence, intrapartum care is an important priority for society. The American Journal of Obstetrics & Gynecology has devoted two special Supplements in 2023 and 2024 to the clinical aspects of labor at term. This article describes the content of the Supplements and highlights new developments in the induction of labor (a comparison of methods, definition of failed induction, new pharmacologic agents), management of the second stage, the value of intrapartum sonography, new concepts on soft tissue dystocia, optimal care during the third stage, and common complications that account for maternal death, such as infection, hemorrhage, and uterine rupture. All articles are available to subscribers and non-subscribers and have supporting video content to enhance dissemination and improve intrapartum care. Our hope is that no mother suffers because of lack of information.

The physiology and pharmacology of oxytocin in labor and in the peripartum period.

Oxytocin is a reproductive hormone implicated in the process of parturition and widely used during labor. Oxytocin is produced within the supraoptic nucleus and paraventricular nucleus of the hypothalamus and released from the posterior pituitary lobe into the circulation. Oxytocin is released in pulses with increasing frequency and amplitude in the first and second stages of labor, with a few pulses released in the third stage of labor. During labor, the fetus exerts pressure on the cervix of the uterus, which activates a feedforward reflex-the Ferguson reflex-which releases oxytocin. When myometrial contractions activate sympathetic nerves, it decreases oxytocin release. When oxytocin binds to specific myometrial oxytocin receptors, it induces myometrial contractions. High levels of circulating estrogen at term make the receptors more sensitive. In addition, oxytocin stimulates prostaglandin synthesis and release in the decidua and chorioamniotic membranes by activating a specific type of oxytocin receptor. Prostaglandins contribute to cervical ripening and uterine contractility in labor. The oxytocin system in the brain has been implicated in decreasing maternal levels of fear, pain, and stress, and oxytocin release and function during labor are stimulated by a social support. Moreover, studies suggest, but have not yet proven, that labor may be associated with long-term, behavioral and physiological adaptations in the mother and infant, possibly involving epigenetic modulation of oxytocin production and release and the oxytocin receptor. In addition, infusions of synthetic oxytocin are used to induce and augment labor. Oxytocin may be administered according to different dose regimens at increasing rates from 1 to 3 mIU/min to a maximal rate of 36 mIU/min at 15- to 40-minute intervals. The total amount of synthetic oxytocin given during labor can be 5 to 10 IU, but lower and higher amounts of oxytocin may also be given. High-dose infusions of oxytocin may shorten the duration of labor by up to 2 hours compared with no infusion of oxytocin; however, it does not lower the frequency of cesarean delivery. When synthetic oxytocin is administered, the plasma concentration of oxytocin increases in a dose-dependent way: at infusion rates of 20 to 30 mIU/min, plasma oxytocin concentration increases approximately 2- to 3-fold above the basal level. Synthetic oxytocin administered at recommended dose levels is not likely to cross the placenta or maternal blood-brain barrier. Synthetic oxytocin should be administered with caution as high levels may induce tachystole and uterine overstimulation, with potentially negative consequences for the fetus and possibly the mother. Of note, 5 to 10 IU of synthetic oxytocin is often routinely given as an intravenous or intramuscular bolus administration after delivery to induce uterine contractility, which, in turn, induces uterine separation of the placenta and prevents postpartum hemorrhage. Furthermore, it promotes the expulsion of the placenta.

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.

Optimizing the length of the second stage and management of pushing.

Although the optimal length of the second stage of labor to minimize maternal and neonatal morbidities and optimize spontaneous vaginal delivery is not known, available evidence suggests that increasing length of the second stage is associated with increasing maternal and neonatal morbidity. Thus, evidence-based strategies to safely shorten the second stage, such as initiating pushing when complete dilation is reached among those with neuraxial anesthesia, is prudent. Many aspects of optimal management of the second stage of labor require future study to continue to guide clinical second-stage management.

Soft-tissue dystocia due to paradoxical contraction of the levator ani as a cause of prolonged second stage: concept, diagnosis, and potential treatment.

Smaller pelvic floor dimensions seem to have been an evolutionary need to provide adequate support for the pelvic organs and the fetal head. Pelvic floor dimension and shape contributed to the complexity of human birth. Maternal pushing associated with pelvic floor muscle relaxation is key to vaginal birth. Using transperineal ultrasound, pelvic floor dimensions can be objectively measured in both static and dynamic conditions, such as pelvic floor muscle contraction and pushing. Several studies have evaluated the role of the pelvic floor in labor outcomes. Smaller levator hiatal dimensions seem to be associated with a longer duration of the second stage of labor and a higher risk of cesarean and operative deliveries. Furthermore, smaller levator hiatal dimensions are associated with a higher fetal head station at term of pregnancy, as assessed by transperineal ultrasound. With maternal pushing, most women can relax their pelvic floor, thus increasing their pelvic floor dimensions. Some women contract rather than relax their pelvic floor muscles under pushing, which is associated with a reduction in the anteroposterior diameter of the levator hiatus. This phenomenon is called levator ani muscle coactivation. Coactivation in nulliparous women at term of pregnancy before the onset of labor is associated with a higher fetal head station at term of pregnancy and a longer duration of the second stage of labor. In addition, levator ani muscle coactivation in nulliparous women undergoing induction of labor is associated with a longer duration of the active second stage of labor. Whether we can improve maternal pelvic floor relaxation with consequent improvement in labor outcomes remains a matter of debate. Maternal education, physiotherapy, and visual feedback are promising interventions. In particular, ultrasound visual feedback before the onset of labor can help women increase their levator hiatal dimensions and correct levator ani muscle coactivation in some cases. Ultrasound visual feedback in the second stage of labor was found to help women push more efficiently, thus obtaining a lower fetal head station at ultrasound and a shorter duration of the second stage of labor. The available evidence on the role of any intervention aimed to aid women to better relax their pelvic floor remains limited, and more studies are needed before considering its routine clinical application.