Assisted Vaginal Delivery Research Articles

Transient Isolated Polyhydramnios and Perinatal Outcomes.

To evaluate labor and perinatal outcomes of transient isolated polyhydramnios. A retrospective cohort study (2008-2013) at a university-affiliated, tertiary medical center. Eligibility was limited to patients with singleton gestations, no maternal diabetes or known structural/chromosomal anomalies, and no rupture of the membranes prior to delivery, at > 34 weeks of gestation. All women underwent routine sonogram for estimation of fetal weight (sEFW) between 28-34 weeks of gestation, and a second routine sonogram at admission. We compared women diagnosed with polyhydramnios at the time of the sEFW which later resolved, with women who had normal AFI during the sEFW. Overall, 44 263 women delivered during this time period, of which 292 (0.7 %) with transient polyhydramnios (study group) and 29 682 with a normal amniotic fluid level (control group) were eligible for analysis. Women with transient polyhydramnios had a higher risk for assisted vaginal delivery (AVD), mainly due to abnormal/intermediate fetal heart rate tracings (aOR 2.3, 95 % CI 1.2-5.5), and a higher risk for cesarean delivery (CD), mostly because of labor dystocia (aOR 2.5, 95 % CI 1.2-5.1 for 1st stage arrest and aOR 3.4, 95 % CI 1.6-7.2) for 2nd stage arrest), suspected macrosomia (aOR 3.2, 95 % CI 1.6-6.6) and malpresentation (aOR 6.6, 95 % CI 2.0-21.1). Transient isolated polyhydramnios detected during the sonogram at 28-32 weeks of gestation is an independent risk factor for the need for obstetrical intervention during labor.

Is there any association between abdominal strength training before and during pregnancy and delivery outcome? The Norwegian Mother and Child Cohort Study

BackgroundAbdominal strength training before and during pregnancy has been recommended to enhance normal vaginal birth by enabling increased force needed for active pushing. However, to date there is little research addressing this hypothesis. ObjectiveTo investigate whether nulliparous pregnant women reporting regular abdominal strength training prior to and at two time points during pregnancy have reduced risk of cesarean section, instrumental assisted vaginal delivery and third- and fourth-degree perineal tears. MethodsAnalysis of 36124 nulliparous pregnant women participating in the Norwegian Mother and Child Cohort Study during the period 1999–2009 who responded to questions regards the main exposure; regular abdominal strength training. Data on delivery outcomes were retrieved from the Medical Birth Registry of Norway. Logistic regression analyses were used to evaluate the association between exposure and outcome before pregnancy and at gestational weeks 17 and 30. ResultsAmongst participants, 66.9% reported doing abdominal strength training exercises before pregnancy, declining to 31.2% at gestational week 30. The adjusted odds ratios were 0.97 (95% CI 0.79–1.19) for acute cesarean section, among those training with the same frequency before and during pregnancy compared to those that never trained. The results were similar for instrumental assisted vaginal delivery and third- and fourth-degree perineal tear. ConclusionThere was no association between the report of regular abdominal strength training before and during pregnancy and delivery outcomes in this prospective population-based cohort.

Perinatal variables influencing cord blood thyroid stimulating hormone

Background: Newborn screening using cord blood Thyroid Stimulating Hormone (TSH) is an effective and an easy way to screen babies for congenital hypothyroidism. Congenital hypothyroidism is a common preventable and treatable cause of mental retardation. Early diagnosis with the help of newborn screening aids in timely management and decreased morbidity. Various maternal and neonatal variables can affect cord blood TSH level thereby affecting the accurate diagnosis of congenital hypothyroidism. This study aims at studying the perinatal variables affecting cord blood TSH.Methods: In a retrospective cross-sectional study conducted in a tertiary care hospital, the hospital case records of 1465 newborn and their mother were studied for variables including cord blood TSH, maternal age, mode of delivery, parity, gender of baby, gestational age and growth of baby. The effect of these perinatal variables on cord blood TSH was analysed statistically. P value below 0.05 was considered as statistically significant. The statistical analysis was done used the SPSS software version 18.0.Results: The median cord blood TSH was 8 microIU/ml (IQR= 6-12) with 8.1% newborns having values more than 20 microIU/ml. Cord blood TSH was significantly raised in male babies (p <0.01) and in neonates born by assisted vaginal delivery (p <0.01). Significant increase in cord blood TSH (p <0.02) was observed in neonates born to primiparous mothers. Maternal age, gestational age of the newborn and growth of the newborn did not have significant effect on cord blood TSH values.Conclusions: The mode of delivery, parity and gender of the baby were found to be significant variables affecting cord blood TSH values. Hence, cord blood TSH values should be interpreted in the light of these perinatal variables.

Induction of Labor in Post Dated Pregnancy with Intra-cervical Foley Catheter in Antenatal Ward

Introduction: Induction of labor is one of the commonest obstetric procedures done these days with the aim of normal vaginal delivery. Among the different methods, transcervical Foley catheter is one of them used with great success and less complications.Objective: This study assesses the effect of intra-cervical Foley catheter in induction of labor in post dated pregnancy.Methodology: This was a descriptive observational study. Patients admitted in antenatal ward of BP Koirala Institute of Health Sciences (BPKIHS) with period of gestation (POG) ≥ 41 weeks without any complications were taken. Patients were induced either with Foley catheter or directly with misoprostol. Patients induced with Foley catheter were included in the study. Sixteen French Gauge Foley catheter was inserted intracervically and bulb was inflated with 40- 60 ml of distilled water and observed for 24 hours. If patient didn't go into labor after 24 hours with or without Foley expulsion, patient was reassessed and prostaglandin was used for further induction. Structured Pro forma was used for data collection and collected data was analyzed using SPSS software 11.5.Results: During the study period 353 patients were induced with intracervical Foley catheter. Among them 97(27.48%) went to labor and 256 (72.52%) needed further prostaglandin. Among 97 patients who went to labor 80 had normal vaginal delivery, 16 underwent cesarean section and one patient had vacuum assisted vaginal delivery. There were nine patients who had delivered baby with meconium stained liquor. Four patients had postpartum hemorrhage and two patients had intrapartum fever. None of the patients had hyper stimulation syndrome but one patient had still birth.Conclusion: Intracervical Foley catheter is one of the options to induce the patient in postdatism for priming the cervix to increase the rate of normal vaginal delivery with less complications.BJHS 2018;3(1)5 : 338-341

Forceps Assisted Vaginal Delivery Simulation Training: Changes in Resident Confidence, Knowledge and Skill [31M

INTRODUCTION: Simulation is a powerful learning tool for low frequency events. In 2015, 3.1% of all deliveries were operative vaginal deliveries and only 0.56% were forceps assisted vaginal deliveries (FAVD). The aim of this study is to create a simulation-based curriculum on FAVD and evaluate resident knowledge, confidence, and performance before and after training. METHODS: An IRB-approved prospective cohort study was conducted. Obstetrics and gynecology residents participated in three hours of a three-part simulation training including a video, didactic teaching, and hands-on simulation practice during the 2016-2017 academic year. A 26 item pre- and post-survey and skills assessments was conducted to assess confidence, knowledge, and ability to perform a forceps delivery. Our primary outcome was improvement in resident confidence and skill. RESULTS: Twenty residents consented to participate and 14 surveys were completed (70%). There was a 28.5% increase in self-perceived confidence before and after training for all residents (P<.001). Significant differences in perceived confidence between resident classes were seen pre-simulation (P<.001). Junior residents demonstrated an increase in perceived confidence (P<.001), while senior residents did not (P=.13). There was an overall improvement in the percentage of residents who performed the required skills for an accurate forceps delivery post-simulation (P=.001). CONCLUSION: Our developed forceps simulation curriculum improves resident perceived confidence and skill. Additional simulation training will involve consenting training sessions. Future analysis will look at the number of forceps deliveries at our institution since the initiation of the simulation-based training curriculum.

Differences in outcomes between cesarean section in the second versus the first stages of labor

Objective: We aimed to compare maternal morbidity and mortality of cesarean sections (CS) in the second versus first stage of labor.Study design: Retrospective study of all CS at a single, university-affiliated medical center, between January 2010 and December 2014. Eligibility was limited to term, singleton pregnancies with cephalic presentation. Maternal outcomes of second-stage CS were compared to those of first-stage CS. The primary outcome was defined as estimated blood loss >1000 ml.Results: Overall, 1004 women met the inclusion criteria, of which 290 (29%) had a second-stage CS and 714 (71%) had a first-stage CS. Women in the second-stage CS group had a higher nulliparity and hypertensive disorders rates and a lower rate of previous CS. Second-stage CS was associated with more than double the rate of estimated blood loss >1000 ml (9.7% versus 3.8%, p<.001), and more prone to unintentional uterine incision extension, uterine atony, hemoglobin decrease >2 g/l and antibiotic treatment for suspected endometritis. In a multivariable logistic regression model, second-stage CS was found to be independently associated with unintentional uterine incision extension (OR 6.8, 95% CI 4.1–11.2), uterine atony (OR 3.3, 95% CI 1.4–8.0) and antibiotic treatment for suspected endometritis (OR 2.6, 95% CI 1.4–5.1), but not with excessive blood loss (OR 1.5, 95% CI 0.8–2.8). Additionally, failed assisted vaginal delivery prior to second-stage CS was not associated with a higher rate of complications.Conclusion: Second-stage CS is associated with higher rates of adverse maternal outcomes, mainly unintentional uterine incision extension, uterine atony, and suspected endometritis.

Failure to perform assisted deliveries is resulting in an increased neonatal and maternal morbidity and mortality: An expert opinion.

The need to perform assisted vaginal delivery (AVD) has been regarded as self-evident. In high-income countries, rates of AVD range between 5% and 20% of all births. In South Africa, the rate of AVD is only 1%. This has resulted in increased neonatal morbidity and mortality due to intrapartum asphyxia, and increased maternal morbidity and mortality due to a rise in second-stage caesarean deliveries. In this article, we address the possible causes leading to a decrease in AVD and propose measures to be taken to increase the rates of AVD and subsequently reduce morbidity and mortality.

Failure to perform assisted deliveries is resulting in an increased neonatal and maternal morbidity and mortality: An expert opinion

The need to perform assisted vaginal delivery (AVD) has been regarded as self-evident. In high-income countries, rates of AVD range between 5% and 20% of all births. In South Africa, the rate of AVD is only 1%. This has resulted in increased neonatal morbidity and mortality due to intrapartum asphyxia, and increased maternal morbidity and mortality due to a rise in second-stage caesarean deliveries. In this article, we address the possible causes leading to a decrease in AVD and propose measures to be taken to increase the rates of AVD and subsequently reduce morbidity and mortality.

A comparative study of low concentration of levobupivacaine versus ropivacaine with fentanyl for patient-controlled epidural labour analgesia

Background and Aims: Lumbar epidural analgesia is considered the modality of choice for labour analgesia. Despite its super analgesia and improved safety profile, it has been associated with maternal adverse effects like higher incidence of instrumental assisted vaginal delivery (AVD) and motor block leading to decreased ambulation. This study was designed to evaluate the efficacy of low concentrations of local anaesthetics (0.1% ropivacaine and 0.1% levobupivacaine) with 2 μg/ml fentanyl as a patient controlled epidural analgesia (PCEA) technique on the incidence of instrumental AVD along with evaluation of obstetric, maternal, and foetal outcomes. Materials and Methods: In this prospective study, 60 labouring parturients were randomly allocated into two equal groups to receive either 0.1% ropivacaine with 2 μg/ml fentanyl or 0.1% levobupivacaine with 2 μg/ml fentanyl as epidural solutions via PCEA pump infusions (4 ml/h) after 15 ml loading dose of the respective solutions. The incidence of instrumental AVD was noted as the primary outcome along with demographic data, maternal and foetal vital parameters, maternal VAS scores, degree of motor blockade and total epidural drug consumption. Results: The incidence of instrumental AVD was found to be 43.3% in the levobupivacaine group and 30% in the ropivacaine group. This difference was not statistically significant. Both the groups were comparable in terms of demographic data, maternal VAS scores, total epidural drug consumption and foetal APGAR scores. Conclusion: The use of newer local anaesthetics (levobupivacaine and ropivacaine) in low concentrations with opioids (fentanyl) as a PCEA technique may offer high maternal satisfaction in terms of quality of pain relief with fewer adverse events like instrumental AVD and adverse foetal outcomes.

Instrumental vaginal deliveries: A review

In contemporary obstetric practice, safety with caesarean section in developed countries has witnessed its increased application in deliveries and the decreasing use of instrumental deliveries. This trend follows the relative hazards complicating instrumental vaginal deliveries and increasing litigations arising thereof. In developing countries however, caesarean sections are not so readily available to parturients and are relatively unsafe, especially with mothers presenting late in health facilities with complicated (commonly obstructed) labors, not infrequently with fetal death. In these circumstances, instrumental vaginal deliveries serve as suitable options. It is with this background that this review considers the role of instrumental vaginal delivery and gives a critical account of current techniques of operative procedures. Important issues, including case choice, documentation, application and use, avoidance of complications, and the need for medical staff training, are included. To this end, nondestructive instrumental (vacuum and forceps), “corrective” instrumental (symphysiotomy), and destructive instrumental assisted vaginal deliveries are considered and carefully analyzed.

366: Long-term pediatric neurologic outcome following cesarean versus assisted vaginal delivery in breech deliveries

366: Long-term pediatric neurologic outcome following cesarean versus assisted vaginal delivery in breech deliveries

An original and effective technique to improve exposure in open surgery

BackgroundExposure, especially when the organs are enlarged, remains one of the most important issue in open surgery. Considering this constraint appears critical in the progress of the surgical procedure. We highlight our technique which affords optimal exposure and improves manipulation and extraction of enlarged organs.ResultsThis original and effective technique is derived from an obstetrical device used to perform an assisted vaginal delivery. It improves exposure, reduces tissue manipulation, and enhances removal of the surgical specimen during hysterectomies and myomectomies. It can be similarly helpful sometimes to grasp and remove (by mini laparotomy) enlarged adnexa during laparoscopic procedures. Moreover, this trick appears particularly suited in case of obese patients.ConclusionThis new technique procures a real benefit for both the patient and the surgeon in terms of ergonomics and safety.

Assisted vaginal delivery in low and middle income countries: an overview.

To assess the use of assisted vaginal delivery (AVD) in low- and middle-income countries (LMICs), highlighting what level of care procedures were performed and identifying systemic barriers to its use. Cross-sectional health facility assessments. Up to 40 countries in Latin America, sub-Saharan Africa and Asia. Assessments tended to be national in scope and included all hospitals and samples of midlevel facilities in public and private sectors. Descriptive secondary data analysis. Percentage of facilities where health workers performed AVD in the 3 months prior to the assessment, instrument preference, which health workers performed the procedure, and reasons AVD was not practiced. Fewer than 20% of facilities in Latin America reported performing AVD in the last 3 months. In sub-Saharan Africa, 53% of 1728 hospitals had performed AVD but only 6% of nearly 10 000 health centres had done so. It was not uncommon to find <1% of institutional births delivered by AVD. Vacuum extraction appears preferred over forceps. Lack of equipment and trained health workers were the most frequent reasons for non-performance. The low use of AVD in LMICs is in contrast with many high-income countries, where high caesarean rates are also associated with significant rates of AVD. In many LMICs, rising caesarean rates have not been associated with maintenance of skills and practice of AVD. AVD is underused precisely in countries where pregnant women continue to face hardships accessing emergency obstetric care and where caesarean delivery can be relatively unsafe. Many LMICs exhibit low use of assisted vaginal delivery where access to EmONC continues to be a hardship.

Vacuum Assisted Vaginal Delivery in Singleton Term Pregnancies: Short Term Maternal and Neonatal Outcome in a Tertiary Hospital of Nepal

Introduction: Other than cesarean delivery, assisted vaginal delivery is an alternative procedure for delivery in emergency obstetrics. Presently, vacuum delivery has gained more popularity than forceps for operative/ assisted vaginal delivery, when and where indicated, with success as well as lesser neonatal and maternal complications. This study was done to estimate the short term maternal and fetal morbidity/mortality due to vacuum assisted vaginal delivery.&#x0D; &#x0D; Methods: A prospective observational study was conducted at Lumbini Medical College Teaching Hospital from January 2015 to May 2016. One hundred and four pregnant women who had successful vacuum assisted vaginal deliveries were enrolled. Fetal and maternal outcome were assessed.&#x0D; &#x0D; Results: One hundred and four successful vacuum deliveries (2.9%) were conducted among 3457 deliveries during our study period. Sixty seven (64.4%) were primigravida and most (n=59, 56.7%) parturients were of age group 20-30 years. The commonest (n=65, 62.5%) indication for vacuum application was prolonged second stage of labor. The maternal morbidity variables were: 6.7% (n=7) had genital tract injury, 3.8% (n=4) had primary post-partum hemorrhage, 3.8% (n=4) had urinary retention, 2.8% (n=3) needed blood transfusion. Among neonatal morbidity indicators, 19.2% (n=20) neonates had birth asphyxia, 4.8% (n=5) neonates had cephalohematoma, 0.96% (n=1) had brachial plexus injury. There was one early neonatal death due to meconium aspiration syndrome.&#x0D; &#x0D; Conclusion: A successful vacuum assisted delivery can be achieved with lesser maternal and neonatal morbidity with timely assessment of labor, skilled operator, and availability of neonatal team.

Reducing obstetric anal sphincter injuries using perineal support: our preliminary experience.

Obstetric anal sphincter injuries (OASIs) are associated with significant short-term and long-term morbidity. Over the past decade, there has been a steady rise in the rate of OASIs. There is therefore a compelling need to identify strategies to minimize OASIs. The objective of this study was to determine if perineal support at the time of vaginal delivery can reduce the incidence and severity of OASIs. All labour ward staff including midwives and doctors were invited to train in the technique of perineal support during vaginal delivery. Two experts from Norway conducted workshops with practical hands-on training on pelvic models. The midwives and doctors underwent further training with women in labour, and mandatory training was continued within the department. All midwives and doctors were instructed to support the perineum during both spontaneous and assisted vaginal delivery. From April 2011 to November 2014, 11,135 women underwent vaginal delivery. The OASI rate decreased from 4.7% to 4.1% (p = 0.11). There was a significant reduction (0.9% to 0.3%, p < 0.001) in 3c third-degree and fourth-degree tears (major OASIs). In a multivariate analysis, perineal support was associated with a significant reduction in the rates of OASIs (23%; OR 0.77, 95% CI 0.63-0.95, p = 0.01]) and major OASIs (71%; OR 0.34, 95% CI 0.17-0.69, p = 0.03). This interventional study showed that perineal support during vaginal delivery can reduce the risk of major OASIs. With sustained reinforcement of this intervention programme, we anticipate a further reduction in OASI rates.

Assessment of an urgency classification for assisted vaginal delivery

We performed a prospective observational audit to evaluate the application of the Lucas caesarean section urgency classification to assisted vaginal delivery in the operating theatre. We collected data from 400 women having category 1–3 delivery in the operating theatre. Twenty percent of the caesarean sections and 4% of the vaginal deliveries were category 1. The median (IQR) decision-delivery interval was 25 (19.5–37) min for category 1 caesarean section and 19.5 (15–29) min for category 1 vaginal delivery, and 43.5 (36–57) min and 45 (32–57) for category 2 caesarean section and vaginal delivery, respectively. Sixty-three percent of category 1 caesarean section and 75% of category 1 vaginal delivery were performed in ≤30 min. Antenatal or intrapartum risk factors were present before the decision for delivery in 82% of caesarean sections and 80% of vaginal deliveries. The application of the Lucas urgency classification to assisted vaginal delivery merits further evaluation.

Effect of maternal and neonatal factors on cord blood thyroid stimulating hormone.

Background:Congenital hypothyroidism (CH) is most common preventable cause of mental retardation in children. Cord blood Thyroid Stimulating Hormone (CBTSH) level is an accepted screening tool for CH.Objectives:To study CBTSH profile in neonates born at tertiary care referral center and to analyze the influence of maternal and neonatal factors on their levels.Design:Cross retrospective sectional study.Methods:Study population included 979 neonates (males = 506 to females = 473). The CBTSH levels were estimated using electrochemiluminescence immunoassay on Cobas analyzer. Kit based cut-offs of TSH level were used for analysis. All neonates with abnormal CBSTH levels, were started on levothyroxine supplementation 10 μg/Kg/day and TSH levels were reassessed as per departmental protocol.Results:The mean CBTSH was 7.82 μIU/mL (Range 0.112 to 81.4, SD = 5.48). The mean CBTSH level was significantly higher in first order neonates, neonates delivered by assisted vaginal delivery and normal delivery, delivered at term or preterm, neonates with APGAR score <5 and those needing advanced resuscitation after birth. The CBTSH level >16.10 and <1.0 μIU/mL was found in 4.39 % and 1.02 % neonates respectively. The prevalence rate of CBTSH level >16.1 μIU/mL was significantly higher in neonates delivered by assisted vaginal delivery and normal delivery, term and preterm neonates, APAGR score of <5, presence of fetal distress, need for resuscitation beyond initial steps and in those with birth weight of <1.5 Kg. Three neonates were confirmed to have CH after retesting of TSH level.Conclusions:The CBTSH estimation is an easy, non-invasive method for screening for CH. The cutoff level of CB TSH (μIU/mL) >16.10 and <1.0 led to a recall of 5.41% of neonates which is practicable given the scenario in our Country. The mode of delivery and perinatal stress factors have a significant impact on CBTSH levels and any rise to be seen in the light of these factors. The prevalence rate of CH after recall was ~3 in 1000 live births.

Turning Disaster into an Opportunity for Quality Improvement in Essential Intrapartum and Newborn Care Services in the Philippines: Pre- to Posttraining Assessments.

Background. On 8 November 2013, supertyphoon Haiyan made landfall in the Philippines, severely disrupting health service delivery. Reestablishment of essential services for birthing mothers and their newborns became high priority. Methodology. Following a baseline assessment, an Essential Intrapartum and Newborn Care (EINC) training package was implemented and posttraining assessments (1 and 3 months after training) were undertaken. Results. Baseline assessments (n = 56 facilities) revealed gaps in provider's skill and shortage of life-saving commodities. Facilities lacked newborn bags/masks (9%), towels (6%), and magnesium sulfate (39%). Service providers lacked skills in partograph use (54%), antenatal steroid (44%) use, and breastfeeding initiation (50%). At 3 months after training (n = 51 facilities), dramatic increases in correct partograph use (to 92%), antenatal steroid use (to 98%), breastfeeding initiation (to 86%), kangaroo mother care (to 94%), availability of magnesium sulfate (to 94%), and bag/masks (to 88%) were documented. Gaps persisted for skills in assisted vaginal delivery and removal of placental fragments. Conclusion. Health services were severely disrupted after supertyphoon Haiyan. Our study demonstrates that essential birthing services and quality improvements to strengthen local health systems can be restored in a timely manner even in immediate postdisaster settings.

Birth by Caesarean Section and the Risk of Adult Psychosis: A Population-Based Cohort Study.

Despite the biological plausibility of an association between obstetric mode of delivery and psychosis in later life, studies to date have been inconclusive. We assessed the association between mode of delivery and later onset of psychosis in the offspring. A population-based cohort including data from the Swedish National Registers was used. All singleton live births between 1982 and 1995 were identified (n= 1,345,210) and followed-up to diagnosis at age 16 or later. Mode of delivery was categorized as: unassisted vaginal delivery (VD), assisted VD, elective Caesarean section (CS) (before onset of labor), and emergency CS (after onset of labor). Outcomes included any psychosis; nonaffective psychoses (including schizophrenia only) and affective psychoses (including bipolar disorder only and depression with psychosis only). Cox regression analysis was used reporting partially and fully adjusted hazard ratios (HR) with 95% confidence intervals (CI). Sibling-matched Cox regression was performed to adjust for familial confounding factors. In the fully adjusted analyses, elective CS was significantly associated with any psychosis (HR 1.13, 95% CI 1.03, 1.24). Similar findings were found for nonaffective psychoses (HR 1.13, 95% CI 0.99, 1.29) and affective psychoses (HR 1.17, 95% CI 1.05, 1.31) (χ(2)for heterogeneityP= .69). In the sibling-matched Cox regression, this association disappeared (HR 1.03, 95% CI 0.78, 1.37). No association was found between assisted VD or emergency CS and psychosis. This study found that elective CS is associated with an increase in offspring psychosis. However, the association did not persist in the sibling-matched analysis, implying the association is likely due to familial confounding by unmeasured factors such as genetics or environment.

Measurement of subpubic arch angle by three-dimensional transperineal ultrasound and impact on vaginal delivery.

To assess whether antepartum measurement of the subpubic arch angle (SPAA) as a parameter of the bony pelvic outlet can predict vaginal delivery. Between January 2007 and June 2011, 625 nulliparous women with a singleton pregnancy were recruited from the antenatal clinic to be interviewed and have a four-dimensional transperineal ultrasound examination. Ultrasound examinations were performed between 34 and 36 weeks of gestation. Volume ultrasound data were saved for offline analysis, blinded against all other data. The SPAA was measured in the axial plane and logistic regression analysis was used to examine the association between SPAA and outcomes of vaginal delivery vs Cesarean section in the second stage of labor, and normal vs assisted vaginal delivery. The association between SPAA and the duration of second stage of labor was also analyzed. Of the 625 women recruited initially, 14 ultrasound data files could not be retrieved, providing a total of 611 ultrasound images for measurement of SPAA. Complete obstetric and ultrasound data were obtained from 593 patients. Mean SPAA was 109.3° (range, 65.6-131.6°). There was no association between SPAA and the odds of a vaginal delivery (odds ratio, 1.01 (95% CI, 0.97-1.06)). However, there was evidence of an association between SPAA and duration of second stage of labor within the subgroup of women with a normal vaginal delivery (cause-specific hazard ratio, 1.02 (95% CI, 1.01-1.03); P = 0.003). SPAA is not useful for predicting vaginal delivery; however, there is an association between this parameter and the duration of the second stage of labor.