A deep learning approach to identify the fetal head position using transperineal ultrasound during labor.

OBJECTIVES: To develop a deep learning (DL)-model using convolutional neural networks (CNN) to automatically identify the fetal head position at transperineal ultrasound in the second stage of labor. MATERIAL AND METHODS: Prospective, multicenter study including singleton, term, cephalic pregnancies in the second stage of labor. We assessed the fetal head position using transabdominal ultrasound and subsequently, obtained an image of the fetal head on the axial plane using transperineal ultrasound and labeled it according to the transabdominal ultrasound findings. The ultrasound images were randomly allocated into the three datasets containing a similar proportion of images of each subtype of fetal head position (occiput anterior, posterior, right and left transverse): the training dataset included 70 %, the validation dataset 15 %, and the testing dataset 15 % of the acquired images. The pre-trained ResNet18 model was employed as a foundational framework for feature extraction and classification. CNN1 was trained to differentiate between occiput anterior (OA) and non-OA positions, CNN2 classified fetal head malpositions into occiput posterior (OP) or occiput transverse (OT) position, and CNN3 classified the remaining images as right or left OT. The DL-model was constructed using three convolutional neural networks (CNN) working simultaneously for the classification of fetal head positions. The performance of the algorithm was evaluated in terms of accuracy, sensitivity, specificity, F1-score and Cohen's kappa. RESULTS: Between February 2018 and May 2023, 2154 transperineal images were included from eligible participants across 16 collaborating centers. The overall performance of the model for the classification of the fetal head position in the axial plane at transperineal ultrasound was excellent, with an of 94.5 % (95 % CI 92.0--97.0), a sensitivity of 95.6 % (95 % CI 96.8-100.0), a specificity of 91.2 % (95 % CI 87.3-95.1), a F1-score of 0.92 and a Cohen's kappa of 0.90. The best performance was achieved by the CNN1 - OA position vs fetal head malpositions - with an accuracy of 98.3 % (95 % CI 96.9-99.7), followed by CNN2 - OP vs OT positions - with an accuracy of 93.9 % (95 % CI 89.6-98.2), and finally, CNN3 - right vs left OT position - with an accuracy of 91.3 % (95 % CI 83.5-99.1). CONCLUSIONS: We have developed a DL-model capable of assessing fetal head position using transperineal ultrasound during the second stage of labor with an excellent overall accuracy. Future studies should validate our DL model using larger datasets and real-time patients before introducing it into routine clinical practice.

Association between interpregnancy interval and the labor curve.

BACKGROUND: Both short and long interpregnancy intervals are associated with adverse pregnancy outcomes; however, the impact of interpregnancy intervals on labor progression is unknown. OBJECTIVE: We examined the impact of interpregnancy intervals on the labor curve, hypothesizing that those with a longer interpregnancy intervals would have slower labor progression. STUDY DESIGN: This is a retrospective cohort study of patients with a history of one prior vaginal delivery admitted for induction of labor or spontaneous labor with a singleton gestation ≥37 weeks at an academic medical center between 2004 and 2015. Repeated measures regression was used to construct labor curves, which were compared between patients with short interpregnancy intervals, defined as <3 years since the last delivery, and long interpregnancy intervals, defined as >3 years since the last delivery. We chose this interval as it approximates the median birth interval in the United States. Interval-censored regression was used to estimate the median duration of labor after 4 centimeters of dilation, stratified by type of labor (spontaneous vs induced). Multivariate analysis was used to adjust for potential confounders. RESULTS: Of the 1331 patients who were included in the analysis, 544 (41%) had a long interpregnancy interval. Among the entire cohort, there were no significant differences in first or second-stage progression between short and long interpregnancy interval groups. In the stratified analysis, first-stage progression varied between groups on the basis of labor type: long interpregnancy interval was associated with a slower active phase among those being induced and a quicker active phase among those in spontaneous labor. The second-stage duration was similar between cohorts regardless of labor type. CONCLUSION: Multiparas with an interpregnancy interval >3 years may have a slower active phase than those with a shorter interpregnancy interval when undergoing induction of labor. Interpregnancy interval does not demonstrate an effect on the length of the second stage.

Impact of collegial midwifery assistance during second stage of labour on women's experience: a follow-up from the Swedish Oneplus randomised controlled trial.

OBJECTIVE: To compare experiences of the second stage of labour in women randomised to assistance by one or by two midwives to reduce severe perineal trauma (SPT). DESIGN: Analysis of a secondary outcome within the Swedish Oneplus multicentre randomised trial. SETTING: Five obstetric units in Sweden between December 2018 and March 2020. PARTICIPANTS: Inclusion criteria in the Oneplus trial were women opting for their first vaginal birth from gestational week 37+0 with a singleton pregnancy and a live fetus in the vertex presentation. Further inclusion criteria were language proficiency in Swedish, English, Arabic or Farsi. Exclusion criteria were multiple pregnancies, intrauterine fetal demise and planned caesarean section. Of the 3059 women who had a spontaneous vaginal birth, 2831 women had consented to participate in the follow-up questionnaire. INTERVENTIONS: Women were randomly assigned (1:1) to assistance by two midwives (intervention group) or one midwife (standard care) when reaching the second stage of labour. OUTCOME MEASURES: Data were analysed by intention to treat. Comparisons between intervention and standard care regarding experiences of the second stage of labour were evaluated with items rated on Likert scales. The Student's t-test was used to calculate mean differences with 95% CIs. RESULTS: In total 2221 (78.5%) women responded to the questionnaire. There were no statistically significant differences regarding women's experiences of being in control, feelings of vulnerability or pain. Women randomised to be assisted by two midwives agreed to a lesser extent that they could handle the situation during the second stage (mean 3.18 vs 3.26, 95% CI 0.01 to 0.15). Conducted subgroup analyses revealed that this result originated from one of the study sites. CONCLUSIONS: The intervention's lack of impact on the experience of the second stage is of importance considering the reduction in SPT when being assisted by two midwives. TRIAL REGISTRATION NUMBER: NCT03770962.

Women's experience of adopting lateral positions during the second stage of labour compared with conventional lithotomy positions: A cross-sectional study.

AIMS: Maternal positions during childbirth play an important role in safe vaginal births and might also influence women's childbirth experiences greatly. Lateral positions, as a potential position to reduce negative maternal and neonatal outcomes, have become popular in recent years, especially in China where the adoption of conventional lithotomy positions is still common. However, the childbirth experience of those who gave birth in lateral positions has been rarely studied. This study aimed to describe and compare women's childbirth experiences of adopting the newly introduced lateral positions and the conventional lithotomy positions during the second stage of labour. STUDY DESIGN: A cross-sectional study was conducted in two tertiary hospitals in China involving a total of 658 primiparous and parous women who adopted lateral and lithotomy positions during the second stage of labour from July to November 2020. Sociodemographic characteristics, maternal and neonatal outcomes as well as childbirth experience assessed by the Childbirth Experience Questionnaire (CEQ) were collected. This study followed the STROBE guidelines. RESULTS: Women who once adopted lateral positions during the second stage of labour had better positive childbirth experiences compared with those in the lithotomy positions group, as demonstrated by their overall higher CEQ scores. Women in the lateral position group also reported better participation and perceived safety, and a greater sense of control during childbirth. Lateral positions remained an influential factor in CEQ scores after controlling for potential confounders. In this study, adverse maternal and neonatal outcomes were rare. Women in lateral positions had comparatively better perineal outcomes. CONCLUSION: This study described and compared women's childbirth experiences of adopting conventional lithotomy positions and lateral positions during the second stage of labour using a valid instrument. Women who adopted lateral positions during the second stage of labour reported better childbirth experiences than those giving birth in the conventional lithotomy positions. Thus, assisting women in giving birth in lateral positions might be a promising way to improve women's childbirth experience.

Nulliparous women's lived experiences of the prolonged passive stage of labour: A thematic analysis based on descriptive phenomenology.

INTRODUCTION: Prolonged progress can occur in the first and second stages of labour and may contribute to a negative birth experience. However, previous studies have mainly focused on quantitative aspects or overall birth experience, and little is known about women's experiences of a prolonged passive second stage. OBJECTIVE: To describe the lived experiences of a prolonged passive second stage of labour in nulliparous women. METHODS: A qualitative study was conducted with 15 nulliparous women with a passive second stage lasting three hours or more. Data were analysed using thematic analysis based on descriptive phenomenology. RESULTS: The analysis resulted in four themes: "An unknown phase" that entailed remaining in a phase that the women lacked an awareness of. "Trust and mistrust in the body's ability" represents the mindset for vaginal birth as well as feelings of powerlessness and self-guilt. The theme "Loss of control" included experiences of frustration, fatigue, and having to deny bodily instincts. "Support through presence and involvement" signifies support through the midwife's presence in the birthing room, although there were also descriptions of emotional or physical absence. CONCLUSIONS: The findings contribute to the understanding of prolonged labour based on women's lived experiences and add to the body of knowledge about the prolonged passive second stage. This study highlights that women need support through information, presence, and encouragement to remain in control. It can be beneficial during birth preparation to include knowledge about the passive second stage together with unexpected or complicated situations during birth, such as prolonged labour.

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.

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.

Informed consent to midwifery practices and interventions during the second stage of labor-An observational study within the Oneplus trial.

OBJECTIVES: To study informed consent to midwifery practices and interventions during the second stage of labor and to investigate the association between informed consent and experiences of these practices and interventions and women's experiences of the second stage of labor. METHODS: This study uses an observational design with data from a follow-up questionnaire sent to women one month after giving birth spontaneously in the Oneplus trial, a study aimed at evaluating collegial midwifery assistance to reduce severe perineal trauma. The trial was conducted between 2018-2020 at five Swedish maternity wards and trial registered at clinicaltrials.gov, no NCT03770962. The follow-up questionnaire contained questions about experiences of the second stage of labor, practices and interventions used and whether the women had provided informed consent. Evaluated practices and interventions were the use of warm compresses held at the perineum, manual perineal protection, vaginal examinations, perineal massage, levator pressure, intermittent catheterization of the bladder, fundal pressure, and episiotomy. Associations between informed consent and women's experiences were assessed by univariate and multivariable logistic regression. FINDINGS: Of the 3049 women participating in the trial, 2849 consented to receive the questionnaire. Informed consent was reported by less than one in five women and was associated with feelings of being safe, strong, and in control. Informed consent was further associated with more positive experiences of clinical practices and interventions, and with less discomfort and pain from interventions involving physical penetration of the genital area. CONCLUSION: The findings indicate that informed consent during the second stage is associated with feelings of safety and of being in control. With less than one in five women reporting informed consent to all practices and interventions performed by midwives, the results emphasize the need for further action to enhance midwives' knowledge and motivation in obtaining informed consent prior to performance of interventions.

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).

Factors Associated with Obstetric Anal Sphincter Injury During Vacuum-Assisted Vaginal Delivery.

INTRODUCTION AND HYPOTHESIS: Obstetric anal sphincter injury (OASI) is a major complication associated with vacuum-assisted vaginal delivery (VAVD). The aim of this study was to evaluate risk factors related to vacuum extraction that are associated with OASI. METHODS: This was a case-control study performed at a tertiary university teaching hospital. Included were patients aged 18-45 years who had a singleton pregnancy resulting in a live, term, VAVD. The study group consisted of women diagnosed with OASI following vacuum extraction. The control group included women following VAVD without OASI. Matching at a ratio of 1:2 was performed. Groups were compared regarding demographic, obstetric. and labor-related parameters, specifically focusing on variables related to the vacuum procedure itself. RESULTS: One hundred and ten patients within the study group and 212 within the control group were included in the final analysis. Patients in the OASI group were more likely to undergo induction of labor, use of oxytocin during labor, increased second stage of labor, higher likelihood of the operator being a resident, increased number of pulls, procedure lasting under 10 min, occipito-posterior head position at vacuum initiation, episiotomy, increased neonatal head circumference, and birthweight. Multivariate logistic regression analysis revealed that increased week of gestation (OR 1.67, 95% CI 1.25-2.22, p < 0.001), unsupervised resident performing the procedure (OR 4.63, 95% CI 2.17-9.90), p < 0.001), indication of VAVD being fetal distress (OR 2.72, 95% CI 1.04-7.10, p = 0.041), and length of procedure under 10 min (OR 4.75, 95% CI 1.53-14.68, p = 0.007) were associated with OASI. Increased maternal age was associated with lower risk of OASI (OR 0.9, 95% CI 0.84-0.98, p = 0.012). CONCLUSIONS: When performing VAVD, increased week of gestation, unsupervised resident performing the procedure, fetal distress as vacuum indication, and vacuum procedure under 10 min were associated with OASI. In contrast, increased maternal age was shown to be a protective factor.

Duration of labor in consecutive deliveries: a retrospective data analysis.

PURPOSE: Labor is shorter in multiparous women. However, there are no individualized data on differences in duration of labor for consecutive deliveries in the same parturient. METHODS: We conducted a retrospective data analysis from 2004 to 2021 at the University Hospital of Zurich and included all women with 2 or more vaginal deliveries of a singleton child in cephalic position, between 22 and 42 weeks of gestation. Descriptive statistics were performed with SPSS version 25.0 (IBM, SPSS Inc., USA). The primary endpoint was the ratio between durations of labor stages in consecutive deliveries of the same parturient. RESULTS: A total of 3344 women with 7066 births (2601 first [P0], 2987 s [P1], 1176 third [P2], and 302 fourth [P3]) were included. The ratio of duration of the active first stage of labor between P1 and P0 was 0.49 (95% CI 0.47-0.51, p < 0.001) meaning that the active first stage of labor was 51% shorter. The second stage of labor with a ratio of 0.26 (95% CI 0.24-0.27, p < 0.001) was 74% shorter in P1 compared to P0. Higher birthweight of the first child led to an even greater decrease in duration of the second stage of labor in P1 compared to P0 (p = 0.003). Neuraxial anesthesia was an independent risk factor for a longer duration of labor, irrespective of parity (p < 0.001). Birthweight and HC of the neonates did not significantly differ between the children born by the same women. However, higher birthweight in of the first child significantly augmented the rate of second stage of labor between P0 and P1 (p = 0.003). DISCUSSION: Up to the third delivery, duration of labor decreased with each consecutive delivery of the same parturient. An individualized assessment of the expected duration of labor in multiparous women should be encouraged.

Effects of Fetal Position on the Loading of the Fetal Brain During the Onset of the Second Stage of Labor.

During vaginal delivery, the delivery requires the fetal head to mold to accommodate the geometric constraints of the birth canal. Excessive molding can produce brain injuries and long-term sequelae. Understanding the loading of the fetal brain during the second stage of labor (fully dilated cervix, active pushing, and expulsion of fetus) could thus help predict the safety of the newborn during vaginal delivery. To this end, this study proposes a finite element model of the fetal head and maternal canal environment that is capable of predicting the stresses experienced by the fetal brain at the onset of the second phase of labor. Both fetal and maternal models were adapted from existing studies to represent the geometry of full-term pregnancy. Two fetal positions were compared: left-occiput-anterior and left-occiput-posterior. The results demonstrate that left-occiput-anterior position reduces the maternal tissue deformation, at the cost of higher stress in the fetal brain. In both cases, stress is concentrated underneath the sutures, though the location varies depending on the presentation. In summary, this study provides a patient-specific simulation platform for the study of vaginal delivery and its effect on both the fetal brain and maternal anatomy. Finally, it is suggested that such an approach has the potential to be used by obstetricians to support their decision-making processes through the simulation of various delivery scenarios.

A Prospective Study of Lactate Levels in Uncomplicated Spontaneous and Induced Labor.

OBJECTIVE: Maternal pushing can yield lactate levels that are above the normal range for nonpregnant individuals. Many hospitals require lactate levels as part of sepsis bundles, and this can confuse the clinicians when measured during labor. The objective of this study was to observe lactate levels in uncomplicated labor. STUDY DESIGN: This was a prospective study of patients presenting to Labor and Delivery in early labor. Patients met inclusion criteria if they presented at 37 weeks' gestation or greater and were either 3 to 4 cm dilated, in early labor with rupture of membranes less than 12 hours, or were being induced for oligohydramnios or postdates gestation. A baseline maternal lactate level was collected at enrollment. Further levels were collected at complete cervical dilation and every 30 minutes during the second stage of labor up to 3 hours or until delivery. RESULTS: From January 7, 2021, through December 30, 2021, a total of 148 screened patients met the inclusion criteria and 38 were enrolled. Eight (21%) patients withdrew after baseline lactate level was drawn. Twenty-three (61%) patients had a level drawn at complete dilation. Of the 12 (32%) patients with a lactate level drawn at complete and after 30 minutes of pushing, the mean change in lactate level was 2.0 ± 1.8 mmol/L or 0.07 ± 0.06 mmol/L/min (p < 0.01). This change is more pronounced in the second stage of labor for patients with chorioamnionitis (2.6 mmol/L), although this difference is not statistically significant (p = 0.41). CONCLUSION: Lactate levels increase significantly once a patient reaches complete cervical dilation within 30 minutes of pushing. This increase is more pronounced, although significantly, in patients with chorioamnionitis. As sepsis is one of the leading causes of maternal morbidity and mortality, this pilot study is relevant for providers to see the natural course of lactate levels in labor. KEY POINTS: · The change in lactate level during normal labor is unknown.. · We measured lactate levels in uncomplicated labor.. · Lactate levels can be elevated in uncomplicated labor..

Novel hybrid rigid-deformable fetal modeling for simulating the vaginal delivery within the second stage of labor.

BACKGROUND AND OBJECTIVE: The fetal representation as a 3D articulated body plays an essential role to describe a realistic vaginal delivery simulation. However, the current computational solutions have been oversimplified. The objective of the present work was to develop and evaluate a novel hybrid rigid-deformable modeling approach for the fetal body and then simulate its interaction with surrounding fetal soft tissues and with other maternal pelvis soft tissues during the second stage of labor. METHODS: CT scan data was used for 3D fetal skeleton reconstruction. Then, a novel hybrid rigid-deformable model of the fetal body was developed. This model was integrated into a maternal 3D pelvis model to simulate the vaginal delivery. Soft tissue deformation was simulated using our novel HyperMSM formulation. Magnetic resonance imaging during the second stage of labor was used to impose the trajectory of the fetus during the delivery. RESULTS: Our hybrid rigid-deformable fetal model showed a potential capacity for simulating the movements of the fetus along with the deformation of the fetal soft tissues during the vaginal delivery. The deformation energy density observed in the simulation for the fetal head fell within the strain range of 3 % to 5 %, which is in good agreement with the literature data. CONCLUSIONS: This study developed, for the first time, a hybrid rigid-deformation modeling of the fetal body and then performed a vaginal delivery simulation using MRI-driven kinematic data. This opens new avenues for describing more realistic behavior of the fetal body kinematics and deformation during the second stage of labor. As perspectives, the integration of the full skeleton body, especially the upper and lower limbs will be investigated. Then, the completed model will be integrated into our developed next-generation childbirth training simulator for vaginal delivery simulation and associated complication scenarios.

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.

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.

First and Second Stage Risk Factors Associated with Perineal Lacerations.

OBJECTIVE: To determine intrapartum factors associated with perineal laceration at delivery. METHODS: This was a planned secondary analysis of a multicenter randomized clinical trial of delayed versus immediate pushing among term nulliparous women in labor with neuraxial analgesia conducted in the United States. Intrapartum characteristics were extracted from the medical charts. The primary outcome was perineal laceration, defined as second degree or above, characterized at delivery in women participating in longer term pelvic floor assessments post-delivery. Multivariable logistic regression was used to refine risk estimates while adjusting for randomization group, birth weight, and maternal age. RESULTS: Among the 941 women participating in the pelvic floor follow-up, 40.6% experienced a perineal laceration. No first stage labor characteristics were associated with perineal laceration, including type of labor or length of first stage. Receiving an amnioinfusion appeared protective of perineal laceration (adjusted odds ratio, 0.48; 95% confidence interval 0.26-0.91; P = 0.01). Second stage labor characteristics associated with injury were length of stage (2.01 h vs. 1.50 h; adjusted odds ratio, 1.36; 95% confidence interval 1.18-1.57; P < 0.01) and a prolonged second stage (adjusted odds ratio, 1.64; 95% confidence interval 1.06-2.56; P < 0.01). Operative vaginal delivery was strongly associated with perineal laceration (adjusted odds ratio, 3.57; 95% confidence interval 1.85-6.90; P < 0.01). CONCLUSION: Operative vaginal delivery is a modifiable risk factor associated with an increased risk of perineal laceration. Amnioinfusion appeared protective against injury, which could reflect a spurious finding, but may also represent true risk reduction similar to the mechanism of warm perineal compress.

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.

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

INTRODUCTION: Efforts to reduce primary cesarean birth may include supporting longer second stages of labor. Although midwifery-led care is associated with lower cesarean use, little has been published on associated outcomes of prolonged second stage (≥3 hours of pushing) for nulliparous individuals in US hospital-based midwifery care. Epidural analgesia and the role of passive descent in midwifery-led care are also underexplored in relation to the second stage. In this study, we report the incidence of prolonged second stage stratified by epidural analgesia and/or passive descent. Secondary aims included calculating the odds of cesarean birth, obstetric anal sphincter injury (OASI), postpartum hemorrhage (PPH), and neonatal complications. METHODS: Data were collected prospectively from a single academic center in the United States from 2012 through 2019. Our cohort analysis of labors attended by midwives for nulliparous, term, singleton, and vertex pregnancies included both descriptive and inferential statistics comparing outcomes between prolonged versus nonprolonged pushing groups. We stratified the sample and quantified second stage outcomes by epidural analgesia and by use of passive descent. RESULTS: Of the 1465 births, 17% (n = 247) included prolonged pushing. Cesarean ranged from 2.2% without prolonged pushing to 26.7% with prolonged pushing. Fetal malposition, epidural analgesia, and longer passive descent were more common among those with prolonged active pushing. Despite these factors, neither odds for PPH nor poor neonatal outcomes were associated with prolonged pushing. Those with more than one hour of passive descent in the second stage who also had prolonged active pushing had lower odds for cesarean but higher odds for OASI relative to those who had little passive descent before pushing for more than 3 hours. DISCUSSION: Prolonged pushing occurred in nearly 2 of 10 nulliparous labors. Fetal malposition, epidural analgesia, and prolonged pushing were commonly observed with longer passive descent, cesarean, and OASI. Passive descent in these data likely reflects individualized midwifery care strategies when pushing was complicated by fetal malposition or other complexities.