New labor curves of dilation and station to improve the accuracy of predicting labor progress

BACKGROUND

The diagnosis of failure to progress, the most common indication for intrapartum cesarean delivery, is based on the assessment of cervical dilation and station over time. Labor curves serve as references for expected changes in dilation and fetal descent. The labor curves of Friedman, Zhang et al, and others are based on time alone and derived from mothers with spontaneous labor onset. However, labor induction is now common, and clinicians also consider other factors when assessing labor progress. Labor curves that consider the use of labor induction and other factors that influence labor progress have the potential to be more accurate and closer to clinical decision-making.

OBJECTIVE

This study aimed to compare the prediction errors of labor curves based on a single factor (time) or multiple clinically relevant factors using two modeling methods: mixed-effects regression, a standard statistical method, and Gaussian processes, a machine learning method.

STUDY DESIGN

This was a longitudinal cohort study of changes in dilation and station based on data from 8022 births in nulliparous women with a live, singleton, vertex-presenting fetus ≥35 weeks of gestation with a vaginal delivery. New labor curves of dilation and station were generated with 10-fold cross-validation. External validation was performed using a geographically independent group. Model variables included time from the first examination in the 20 hours before delivery; dilation, effacement, and station recorded at the previous examination; cumulative contraction counts; and use of epidural anesthesia and labor induction. To assess model accuracy, differences between each model's predicted value and its corresponding observed value were calculated. These prediction errors were summarized using mean absolute error and root mean squared error statistics.

RESULTS

Dilation curves based on multiple parameters were more accurate than those derived from time alone. The mean absolute error of the multifactor methods was better (lower) than those of the single-factor methods (0.826 cm [95% confidence interval, 0.820-0.832] for the multifactor machine learning and 0.893 cm [95% confidence interval, 0.885-0.901] for the multifactor mixed-effects method and 2.122 cm [95% confidence interval, 2.108-2.136] for the single-factor methods; P<.0001 for both comparisons). The root mean squared errors of the multifactor methods were also better (lower) than those of the single-factor methods (1.126 cm [95% confidence interval, 1.118-1.133] for the machine learning [P<.0001] and 1.172 cm [95% confidence interval, 1.164-1.181] for the mixed-effects methods and 2.504 cm [95% confidence interval, 2.487-2.521] for the single-factor [P<.0001 for both comparisons]). The multifactor machine learning dilation models showed small but statistically significant improvements in accuracy compared to the mixed-effects regression models (P<.0001). The multifactor machine learning method produced a curve of descent with a mean absolute error of 0.512 cm (95% confidence interval, 0.509-0.515) and a root mean squared error of 0.660 cm (95% confidence interval, 0.655-0.666). External validation using independent data produced similar findings.

CONCLUSION

Cervical dilation models based on multiple clinically relevant parameters showed improved (lower) prediction errors compared to models based on time alone. The mean prediction errors were reduced by more than 50%. A more accurate assessment of departure from expected dilation and station may help clinicians optimize intrapartum management.

Is there a difference in labor patterns after induction with prostaglandins and double-balloon catheters?

BACKGROUND

Labor progression curves are believed to differ between spontaneous and induced labors. However, data describing labor progression patterns with different modes of induction are insufficient.

OBJECTIVE

This study aimed to compare the progress patterns between labors induced with slow-release prostaglandin E2 vaginal analogue and those induced with a double-balloon catheter.

STUDY DESIGN

This retrospective cohort study included all nulliparous women who delivered at term and who underwent cervical ripening with prostaglandin E2 vaginal analogue or a double-balloon catheter from 2013 to 2021 in a tertiary hospital in Israel. Included in the analysis were women who achieved 10 cm cervical dilatation. The time intervals between centimeter-to-centimeter changes were evaluated.

RESULTS

A total of 1087 women were included of whom 786 (72.3%) were induced using prostaglandin E2 vaginal analogue and 301 (27.7%) were induced using a double-balloon catheter. The time from induction to birth was similar between the groups (32.5 hours for the prostaglandin E2 vaginal analogue group [5th-95th percentiles, 6.5-153.8] vs 29.2 hours for the double-balloon group [5th-95th percentiles, 9.1-157.1]; P=.100). The median time of the latent phase (2-6 cm dilation) was longer for the double-balloon catheter group than for the prostaglandin E2 vaginal analogue group (7.3 hours [5th-95th percentiles, 5.6-14.5] vs 6.0 hours [5th-95th percentiles, 2.4-18.8]; P=.042). The median time of active labor (6-10 cm dilatation) was similar between groups (1.9 hours [5th-95th percentiles, 0.3-7.4] for the prostaglandin E2 vaginal analogue group vs 2.3 hours [5th-95th percentiles, 0.3-6.5] for the double-balloon catheter group; P=.307).

CONCLUSION

Deliveries subjected to cervical ripening with a double-balloon catheter were characterized by a slightly longer latent phase than deliveries induced by prostaglandin E2 vaginal analogue. After reaching the active phase of labor, the mode of cervical ripening did not influence the labor progress pattern.

New insights on labor progression: a systematic review

The past 20 years witnessed an invigoration of research on labor progression and a change of thinking regarding normal labor. New evidence is emerging, and more advanced statistical methods are applied to labor progression analyses. Given the wide variations in the onset of active labor and the pattern of labor progression, there is an emerging consensus that the definition of abnormal labor may not be related to an idealized or average labor curve. Alternative approaches to guide labor management have been proposed; for example, using an upper limit of a distribution of labor duration to define abnormally slow labor. Nonetheless, the methods of labor assessment are still primitive and subject to error; more objective measures and more advanced instruments are needed to identify the onset of active labor, monitor labor progression, and define when labor duration is associated with maternal/child risk. Cervical dilation alone may be insufficient to define active labor, and incorporating more physical and biochemical measures may improve accuracy of diagnosing active labor onset and progression. Because the association between duration of labor and perinatal outcomes is rather complex and influenced by various underlying and iatrogenic conditions, future research must carefully explore how to integrate statistical cut-points with clinical outcomes to reach a practical definition of labor abnormalities. Finally, research regarding the complex labor process may benefit from new approaches, such as machine learning technologies and artificial intelligence to improve the predictability of successful vaginal delivery with normal perinatal outcomes.

A wider agreement is needed on basic intrapartum concepts

Healthcare professionals working in labor wards worldwide regularly deal with the pressure of managing an emotionally charged and life-changing period for women, their families, and their friends. Furthermore, they frequently deal with long working hours, sleep deprivation, occasional scrutiny from the press, and legal dispute. The existing disagreements among leading scientific institutions on basic concepts of intrapartum care hinder the creation of a collective mental model in the labor ward, an aspect that is required for consistency in patient counseling and effective teamwork. Some of these disagreements are as follows: 1. When should laboring women be admitted to the hospital? 2. How long is the absence of labor progress acceptable before an intervention is proposed? 3. How long should women be allowed to push during the second stage of labor before an intervention is proposed? The international scientific community owes it to the vast number of healthcare professionals working in labor wards worldwide to agree on and provide clear definitions of these basic intrapartum concepts, thus making their work a little easier. International institutions, such as the International Federation of Gynecology and Obstetrics and the World Health Organization, have the highest authority to produce guidelines for the whole world, but the participation of leading national organizations, whose influence reaches well beyond the borders of their countries, is important for the wide dissemination of concepts.

Partogram of Grandmultiparous Parturients: A Multicenter Cohort Study

Sparse and conflicting data exist regarding the normal partogram of grand-multiparous (GMP, defined as parity of 6+) parturients. Customized partograms may potentially lower cesarean delivery rates for protraction disorders in this population. In this study, we aim to construct a normal labor curve of GMP women and compare it to the multiparous (MP, defined as parity of 2-5) partogram. We conducted a multicenter retrospective cohort analysis of deliveries between the years 2003 and 2019. Eligible parturients were the trials of labor of singletons ≥37 + 0 weeks in cephalic presentation with ≥2 documented cervical examinations during labor. Exclusion criteria were elective cesarean delivery without a trial of labor, preterm labor, major fetal anomalies, and fetal demise. GMP comprised the study group while the MP counterparts were the control group. A total of 78,292 deliveries met the inclusion criteria, comprising 10,532 GMP and 67,760 MP parturients. Our data revealed that during the first stage of labor, cervical dilation progressed at similar rates in MPs and GMPs, while head descent was a few minutes faster in GMPs compared to MPs, regardless of epidural anesthesia. The second stage of labor was faster in GMPs compared to MPs; the 95th percentile of the second stage duration of GMPs (48 min duration) was 43 min less than that of MPs (91 min duration). These findings remained similar among deliveries with and without epidural analgesia or labor induction. We conclude that GMPs' and MPs' cervical dilation progression in the active phase of labor was similar, and the second stage of labor was shorter in GMPs, regardless of epidural use. Thus, GMPs' uterus function during labor corresponds, and possibly surpasses, that of MPs. These findings indicate that health providers can use the standard partogram of the active phase of labor when caring for GMP parturients.

Normal labor curve in twin gestation

BACKGROUND

Failure to progress is one of the leading indications for cesarean delivery in trials of labor in twin gestations. However, assessment of labor progression in twin labors is managed according to singleton labor curves.

OBJECTIVE

This study aimed to establish a partogram for twin deliveries that reflects normal and abnormal labor progression and customized labor curves for different subgroups of twin labors.

STUDY DESIGN

This was a multicenter, retrospective cohort analysis of twin deliveries that were recorded in 3 tertiary medical centers between 2003 and 2017. Eligible parturients were those with twin gestations at ≥34 weeks' gestation with cephalic presentation of the presenting twin and ≥2 cervical examinations during labor. Exclusion criteria were elective cesarean delivery without a trial of labor, major fetal anomalies, and fetal demise. The study group comprised twin gestations, whereas singleton gestations comprised the control group. Statistical analysis was performed using Python 3.7.3 and SPSS, version 27. Categorical variables were analyzed using chi-square tests. Student t test and Mann-Whitney U test were applied to analyze the differences in continuous variables, as appropriate.

RESULTS

A total of 1375 twin deliveries and 142,659 singleton deliveries met the inclusion criteria. Duration of the active phase of labor was significantly longer in twin labors than in singleton labors in both nulliparous and multiparous parturients; the 95th percentile duration was 2 hours longer in nulliparous twin labors and >3.5 hours longer in multiparous twin labors than in singleton labors. The cervical dilation progression rate was significantly slower in twin deliveries than in singleton deliveries with a mean rate in twin deliveries of 1.89 cm/h (95th percentile, 0.51 cm/h) and a mean rate of 2.48 cm/h (95th percentile, 0.73 cm/h) in singleton deliveries (P<.001). In addition, epidural use further slowed labor progression in twin deliveries. The second stage of labor was also markedly longer in twin deliveries, both in nulliparous and multiparous women (95th percentile, 3.04 vs 2.83 hours, P=.002).

CONCLUSION

Twin labors are characterized by a slower progression of the active phase and second stage of labor compared with singleton labors in nulliparous and multiparous parturients. Epidural analgesia further slows labor progression in twin labors. Implementation of these findings in clinical management might lower cesarean delivery rates among cases with protracted labor in twin gestations.

Impact of analysis technique on our understanding of the natural history of labour: a simulation study

OBJECTIVE

To evaluate the discrepancy between historical and more recent descriptions of the first stage of labour by testing whether the statistical techniques used recently (repeated-measures polynomial and interval-censored regression) were appropriate for detection of periods of rapid acceleration of cervical dilatation as might occur at the time of transition from a latent to an active phase of labour.

DESIGN AND SETTING

A simulation study using regression techniques.

SAMPLE

We created a simulated data set for 500 000 labours with clearly defined latent and active phases using the parameters described by Friedman. Additionally, we created a data set comprising 500 000 labours with a progressively increasing rate of cervical dilatation.

METHODS

Repeated-measures polynomial regression was used to create summary labour curves based on simulated cervical examinations. Interval-censored regression was used to create centimetre-by-centimetre estimates of rates of cervical dilatation and their 95th centiles.

MAIN OUTCOME MEASURES

Labour summary curves and rates of cervical dilatation.

RESULTS

Repeated-measures polynomial regression did not detect the rapid acceleration in cervical dilatation (i.e. acceleration phase) and overestimated lengths of labour, especially at smaller cervical dilatations. There was a two-fold overestimation in the mean rate of cervical dilatation from 4 to 6 cm. Interval-censored regression overestimated median transit times, at 4- to 5-cm cervical dilatation or when cervical examinations occurred less frequently than 0.5- to 1.5-hourly.

CONCLUSION

Repeated-measures polynomial regression and interval-censored regression should not be routinely used to define labour progress because they do not accurately reflect the underlying data.

TWEETABLE ABSTRACT

Repeated-measures polynomial and interval-censored regression techniques are not appropriate to model first stage of labour.

Increased length of active labor is associated with adverse perinatal outcomes among nulliparous women undergoing labor induction

OBJECTIVE

Evaluate the association between current recommendations for active labor duration in nulliparous women undergoing labor induction and adverse perinatal outcomes.

STUDY DESIGN

Retrospective cohort study from 2012 to 2015. Subjects were nulliparous, 18-44 years, cephalic, singleton ≥37 weeks undergoing labor induction who reached active labor. We created three subgroups, defined by active labor duration from 6 to 10cm as < the median, median-95th percentile, and >95th percentile based on contemporary labor curves. We evaluated the association between subgroups and cesarean delivery, chorioamnionitis, blood loss (EBL), 5-minute Apgar score < 7, and neonatal intensive care unit (NICU) admission using logistic regression.

RESULTS

Among 356 women, 34.8% had an active labor duration < median, 43.3% were between the median-95th percentile, and 21.9% were >95th percentile. The risk of cesarean delivery increased with longer active labor duration; 1.8-fold (95%CI = 1.1-3.1) and 4.0-fold (95%CI = 2.5-6.5) for women whose active labors were between the median-95th percentile and >95th percentile, respectively. Chorioamnionitis increased by 3.9-fold (95%CI = 1.2-13.2) in the >95th percentile subgroup. Active labor length was not associated with EBL, Apgar scores, or NICU admission.

CONCLUSIONS

Cesarean delivery and chorioamnionitis increased significantly as induced active labor duration exceeded the median. This study provides a better understanding regarding the risks of longer active labor as defined by contemporary labor curves.

Evidence-based labor management: first stage of labor (part 3)

There are several interventions during the first stage of labor that have been studied. Vaginal disinfection with chlorhexidine cannot be recommended. Intrapartum antibiotic prophylaxis is recommended for group B streptococcus-positive women. Antibiotic therapy can be considered in women with term prelabor rupture of membranes whose latency is expected to be >12 hours. Aromatherapy with essential oils through inhalation or back massage can be considered. Immersion in water can be considered. Oral restriction of fluid or solid food is not recommended. In the setting of oral restriction, intravenous fluid containing dextrose at a rate of 250 mL/h is recommended. Upright positions and ambulation are recommended in women without regional anesthesia, and women with regional anesthesia can adopt whatever position they find most comfortable and choose to ambulate or not ambulate. Continuous bladder catheterization cannot be recommended. There is no recommended frequency of cervical examinations or sweeping of membranes. The use of a partogram cannot be recommended as a routine intervention. Routine use of the peanut ball cannot be recommended. Antispasmodic agents cannot be recommended. Routine amniotomy alone in normally progressing spontaneous first stage of labor cannot be recommended. Oxytocin augmentation is recommended to shorten the time to delivery for women making slow progress in spontaneous labor, and higher doses of oxytocin can be considered. Early intervention with oxytocin and amniotomy for the prevention and treatment of dysfunctional or slow labor is recommended. Routine use of intrauterine pressure catheter and ultrasound cannot be recommended. Cesarean delivery for arrest should not be performed unless labor has arrested for a minimum of 4 hours with adequate uterine activity or 6 hours with inadequate uterine activity in a woman with rupture of membranes, adequate oxytocin, and ≥6 cm cervical dilation.

Contemporary patterns of labor in nulliparous and multiparous women

BACKGROUND

Controversy surrounds the definition of "normal" and "abnormal" labor.

OBJECTIVE

In this study, we used contemporary labor charts to explore labor patterns in large obstetric population (2011-2016).

STUDY DESIGN

Detailed information from electronic medical records of live singleton deliveries at term (≥37 weeks of gestation) was extracted. Cases of elective cesarean deliveries, nonvertex presentation, and cesarean deliveries during the first stage of labor were excluded.

RESULTS

Overall, 35,146 deliveries were included, of whom 15,948 deliveries (45.3%) were of nulliparous women. Median cervical dilation at admission was not significantly different between nulliparous (median, 4 cm; interquartile range, 3-5 cm) and multiparous women (median, 4 cm; interquartile range, 3-6 cm). In all, 99.3% of the women delivered vaginally. For nulliparous women, the median duration of the first stage of labor was 274 minutes (interquartile range, 145-441 minutes; 95th percentile, 747.5 minutes). Likewise, for multiparous women, the corresponding duration was 133 minutes (interquartile range, 56-244 minutes; 95th percentile, 494 minutes). During the latent phase (cervical dilation at admission, ≤4 cm), the time elapsed to the second stage of labor was 120-140 minutes longer in nulliparous women, whereas the gap between the groups decreased dramatically with advanced cervical dilation on admission. Nulliparous and multiparous women appeared to progress at a similar pace during the latent phase; however, after 5 cm, labor accelerated faster in multiparous women. Epidural anesthesia lengthens duration first and second stages of labor in all parities. Partograms according to cervical dilation at presentation are proposed.

CONCLUSION

Cervical dilation rate is relatively constant between nulliparous and multiparous pregnant women during the latent phase. Time interval of the first stage was far slower than previously described, which allowed labor to continue for a longer period during this stage. These findings may reduce the rate of intrapartum iatrogenic interventions.

Labor progress determined by ultrasound is different in women requiring cesarean delivery from those who experience a vaginal delivery following induction of labor

BACKGROUND

The diagnosis of labor dystocia generally is determined by the deviation of labor progress, which is assessed by the use of a partogram. Recently, intrapartum transperineal ultrasound for the assessment of fetal head descent has been introduced to assess labor progress in the first stage of labor in a more objective and noninvasive way.

OBJECTIVE

The objective of the study was to determine the differences in labor progress by the use of serial transperineal ultrasound assessment of fetal head descent between women having vaginal and cesarean delivery.

STUDY DESIGN

This was a prospective longitudinal study performed in 315 women with singleton pregnancy who were undergoing labor induction at term between December 2016 and December 2017. Paired assessment of cervical dilation and fetal head station by vaginal examination and transperineal ultrasonographic assessment of parasagittal angle of progression and head-perineum distance were made serially after the commencement of labor induction. According to the hospital protocol, assessment was performed every 24 hours and 4 hours, respectively, during latent and active phases of labor. The researchers and the clinical team were blinded to each other's findings. The repeated measures data were analyzed by mixed effect models. To determine the effect of mode of delivery on the association between parasagittal angle of progression and head-perineum distance against fetal head station and cervical dilation, the significance of the interaction term between each mode of delivery and fetal head station or cervical dilation was determined, which accounted for parity and obesity. Area under receiver-operating characteristic curve was used to evaluate the performance of serial intrapartum sonography in predicting women with cesarean delivery because of failure to progress.

RESULTS

The total number of paired vaginal examination and ultrasound assessments was 1198, with a median of 3 per woman. The median assessment-to-assessment interval was 4.6 hours (interquartile range, 4.3-5.1 hours). Women who achieved vaginal delivery (n=261) had steeper slopes of parasagittal angle of progression and head-perineum distance against fetal head station and cervical dilation than those who achieved cesarean delivery (n=54). Objectively, an additional decrease of 5.11 and 1.37 degrees in parasagittal angle of progression was observed for an unit increase in fetal head station and cervical dilation, respectively, in women who required cesarean delivery (P<.01; P=.01), compared with women who achieved vaginal delivery, after taking account of repeated measures from individuals and confounding factors. The respective additional increases in head-perineum distance for a unit increase in fetal head station and cervical dilation were 0.27 cm (P<.01) and 0.12 cm (P<.01). A combination of maternal characteristics with the temporal changes of parasagittal angle of progression for an unit increase in fetal head station achieved an area under receiver-operating characteristic curve of 0.85 (95% confidence interval, 0.76-0.94), with sensitivity of 79% and specificity of 80%, for the prediction of women who required cesarean delivery because of failure to progress.

CONCLUSION

The differences in labor progress between vaginal and cesarean delivery have been illustrated objectively by serial intrapartum transperineal ultrasonographic assessment of fetal head descent. This tool is potentially predictive of women who will require cesarean delivery because of failure to progress.

Impact factors on fetal descent rates in the active phase of labor: a retrospective cohort study

AIM

To assess fetal descent rates of nulliparous and multiparous women in the active phase of labor and to evaluate significant impact factors.

METHODS

In a retrospective cohort study at the University Hospital of Zurich, Switzerland, we evaluated 6045 spontaneous vaginal deliveries with a singleton in vertex presentation between January 2007 and July 2014 at 34 0/7 to 42 0/7 gestational weeks. Median fetal descent rates and their 10th and 90th percentiles were assessed in the active phase of labor and different impact factors were evaluated.

RESULTS

Fetal descent rates are exponentially increasing. Nulliparous women have slower fetal descent than multiparous women (P<0.001), ranging from 0 to 5.81 cm/h and from 0 to 15 cm/h, respectively. The total duration of fetal descent in labor is 5.42 h for nulliparous and 2.71 h for multiparous women. Accelerating impact factors are a lower fetal station, multiparity, increasing maternal weight and fetal occipitoanterior position, whereas epidural anesthesia decelerates fetal descent (P<0.001).

CONCLUSIONS

Fetal descent is a hyperbolic increasing process with faster descent in multiparous women compared to nulliparous women, is highly inter individual and is associated with different impact factors. The diagnosis of labor arrest or prolonged labor should therefore be based on such rates as well as on individual evaluation of every parturient.

The feasibility and accuracy of ultrasound assessment in the labor room

Objective: Vaginal examination is widely used to assess the progress of labor; however, it is subjective and poorly reproducible. We aim to assess the feasibility and accuracy of transabdominal and transperineal ultrasound compared to vaginal examination in the assessment of labor and its progress. Methods: Women were recruited as they presented for assessment of labor to a tertiary inner city maternity service. Paired vaginal and ultrasound assessments were performed in 192 women at 24-42 weeks. Fetal head position was assessed by transabdominal ultrasound defined in relation to the occiput position transformed to a 12-hour clock face; fetal head station defined as head-perineum distance by transperineal ultrasound; cervical dilatation by anterior to posterior cervical rim measurement and caput succedaneum by skin-skull distance on transperineal ultrasound. Results: Fetal head position was recorded in 99.7% (298/299) of US and 51.5% (154/299) on vaginal examination (p < .0001 ¹ ). Bland-Altman analysis showed 95% limits of agreement, -5.31 to 4.84 clock hours. Head station was recorded in 96.3% (308/320) on vaginal examination (VE) and 95.9% (307/320) on US (p = .79 ¹ ). Head station and head perineum distance were negatively correlated (Spearman's r = -.57, p < .0001). 54.4% (178/327) of cervical dilatation measurements were determined using US and 100% on VE/speculum (p < .0001). Bland-Altman analysis showed 95% limits of agreement -2.51-2.16 cm. The presence of caput could be assessed in 98.4% (315/320) of US and was commented in 95.3% (305/320) of VEs, with agreement for the presence of caput of 76% (p < .05). Fetuses with caput greater than 10 mm had significantly lower head station (p < .0001). Conclusions: We describe comprehensive ultrasound assessments in the labor room that could be translated to the assessment of women in labor. Fetal head position is unreliably determined by vaginal examination and agrees poorly with US. Head perineum distance has a moderate correlation with fetal head station in relation to the ischial spines based on vaginal examination. Cervical dilatation is not reliably assessed by ultrasound except at dilatations of less than 4 cm. Caput is readily quantifiable by ultrasound and its presence is associated with lower fetal head station. Transabdominal and transperineal ultrasound is feasible in the labor room with an accuracy that is generally greater than vaginal examinations.

Impact factors on cervical dilation rates in the first stage of labor

AIMS

To assess cervical dilation rates of nulliparous and multiparous women in the active first stage of labor and to evaluate significant impact factors.

METHODS

In a retrospective cohort study between January 2007 and July 2014 at the University Hospital of Zurich in Switzerland, we analyzed 8378 women with singleton pregnancies in vertex presentation with a vaginal delivery at 34+0 to 42+5 gestational weeks. Median cervical dilation rates were calculated and different impact factors evaluated.

RESULTS

Cervical dilation rates increase during labor progress with faster rates in multiparous compared with nulliparous women (P<0.001). Dilation rates exceed 1 cm/h at a dilatation of 6-7 cm, but are very individual. Accelerating impact factors are multiparity, a greater amount of cervical dilation and fetal occipitoanterior position, whereas the use of epidural anesthesia, a higher fetal weight and head circumference decelerate dilation (P<0.001).

CONCLUSION

Cervical dilation is a hyperbolic increasing process, with faster dilation rates in multiparous compared to nulliparous women and a reversal point of labor around 6-7 cm, respectively. Besides, cervical dilation is highly individual and affected by several impact factors. The diagnosis of labor arrest or prolonged labor should therefore be based on such rates and on the individual evaluation of every woman.

Evaluation of the alert line of partogram in recognizing the need for neonatal resuscitation

Background:

A major problem of the first moments of childbirth, especially in “prolonged labor,” is perinatal asphyxia which necessitates neonatal resuscitation. This study aimed at evaluating the alert line of the partogram in recognizing the need for neonatal resuscitation 20–30 s after delivery.

Materials and Methods:

140 full-term pregnant women were kept under surveillance through using a partogram. In order to decide on the onset of resuscitation, the three indicators of fetal respiration, heart rate, and skin color were used 20–30 s after delivery. The findings from the evaluation of fetal conditions were compared to the position of the ultimate cervical dilatation graph to the alert line of the partogram, and through using appropriate statistical procedures, sensitivity, specificity, and positive and negative prediction values of the alert line to recognize the need for neonatal resuscitation were computed.

Results:

There was a significant relationship between the need for neonatal resuscitation within 20–30 seconds after delivery and the graph of the cervical dilatations on the partogram (P = 0.001). The indices of the alert line for predicting the need for resuscitation 20–30 s after birth had a sensitivity of 97.5%, specificity of 80.2%, positive prediction value of 97.2%, and negative prediction value of 98.7%.

Conclusions:

In mothers who had normal vaginal delivery, with normal fetal heart rate, and with no oxytocin administration or omniotomy, the alert line showed appropriate sensitivity, specificity, and negative prediction value. So, it can assist in predicting the necessity of action for neonatal resuscitation 20–30 s after delivery.

Statistical aspects of modeling the labor curve

In a recent review by Cohen and Friedman, several statistical questions on modeling labor curves were raised. This article illustrates that asking data to fit a preconceived model or letting a sufficiently flexible model fit observed data is the main difference in principles of statistical modeling between the original Friedman curve and our average labor curve. An evidence-based approach to construct a labor curve and establish normal values should allow the statistical model to fit observed data. In addition, the presence of the deceleration phase in the active phase of an average labor curve was questioned. Forcing a deceleration phase to be part of the labor curve may have artificially raised the speed of progression in the active phase with a particularly large impact on earlier labor between 4 and 6 cm. Finally, any labor curve is illustrative and may not be instructive in managing labor because of variations in individual labor pattern and large errors in measuring cervical dilation. With the tools commonly available, it may be more productive to establish a new partogram that takes the physiology of labor and contemporary obstetric population into account.

Misguided guidelines for managing labor

In a recent review we expressed concerns about new guidelines for the assessment and management of labor recommended jointly by the American Congress of Obstetricians and Gynecologists (ACOG) and the Society for Maternal-Fetal Medicine (SMFM). These guidelines are based heavily on a new concept of how cervical dilatation and fetal descent progress, derived from the work of Zhang et al. In their Viewpoint article they have addressed, but not allayed, the concerns we described in our review. We assert that the dilatation curve promulgated by Zhang et al cannot be reconciled with direct clinical observation. Even if they were correct, however, it still does not follow that the ACOG/SMFM guidelines should recommend replacing the coherent system of identifying and managing labor aberrations described by Friedman. That system is grounded in well-established clinical principles based on decades of use and the objectively documented association of some labor abnormalities with poor fetal and maternal outcomes. Recommendations for new clinical management protocols should require the demonstration of superior outcomes through extensive, preferably prospective, assessment. Using untested guidelines for the management of labor may adversely affect women and children. Even if those guidelines were to reduce the currently excessive cesarean delivery rate, the price of that benefit is likely to be a trade-off in harm to parturients and their offspring. The nature and degree of that harm needs to be documented before considering adoption of the guidelines.

Perils of the new labor management guidelines

Recent guidelines issued jointly by the American College of Obstetricians and Gynecologists and the Society for Maternal-Fetal Medicine for assessing labor progress differ substantially from those described initially by Friedman, which have guided clinical practice for decades. The guidelines are based on results obtained from new and untested methods of analyzing patterns of cervical dilatation and fetal descent. Before these new guidelines are adopted into clinical practice, the results obtained by these unconventional analytic approaches should be validated and shown to be superior, or at least equivalent, to currently accepted standards. The new guidelines indicate the patterns of labor originally described by Friedman are incorrect and, further, are inapplicable to modern obstetric practice. We contend that the original descriptions of normal and abnormal labor progress, which were based on direct clinical observations, accurately describe progress in dilatation and descent, and that the differences reported more recently are likely attributable to patient selection and the potential inaccuracy of very high-order polynomial curve-fitting methods. The clinical evaluation of labor is a process of serially estimating the likelihood of a safe vaginal delivery. Because many factors contribute to that likelihood, such as cranial molding, head position and attitude, and the bony architecture and capacity of the pelvis, graphic labor patterns should never be used in isolation. The new guidelines are based heavily on unvalidated notions of labor progress and ignore clinical parameters that should remain cornerstones of intrapartum decision-making.

The sonopartogram: a novel method for recording progress of labor by ultrasound

OBJECTIVES

Progress of labor has hitherto been assessed by digital vaginal examination (VE). We introduce the concept of a non-intrusive ultrasound (US)-based assessment of labor progress (the 'sonopartogram') and investigate its feasibility for assessing cervical dilatation and fetal head descent and rotation.

METHODS

This was a prospective study performed in 20 women in the first stage of labor in two European maternity units. Almost simultaneous assessment of cervical dilatation and fetal head descent and rotation were made by US and digital VE.

RESULTS

The total number of paired US and digital VE assessments was 52, with a median of three per woman. Overall, 5% of sonopartogram parameters were not obtained compared with 18% of conventional digital VE parameters (P < 0.001). Assessment of cervical dilatation was possible in 86.5% of US examinations and 100% of digital VEs (P = 0.02), and dilatation was assessed as being greater by digital VE than by US (mean difference, 1.16 (95% limits of agreement, -0.76, 3.08) cm, r(2) = 0.68, P = 0.01). Fetal head descent was measured in all 52 cases by both methods (r(2) = 0.33, P < 0.001), but correlation between the two was only moderate. Head rotation was obtainable in 98% of US examinations and 46% of digital VEs (P < 0.001), with a mean difference of -3.9° (95% limits of agreement, -144.1°, 136.3°).

CONCLUSION

In this proof-of-concept study, the acquisition of data regarding progress of labor was more successful for the sonopartogram than the conventional partogram. The agreement between digital VE and US was good for cervical dilatation and head rotation but less so for head descent. US assessment of the progress of labor is feasible in most cases.