A clinical prediction model to assess the risk of operative delivery

The relation between low-grade fever during prolonged rupture of membranes (>12 hours) at term and infectious outcomes: a retrospective cohort study

BACKGROUND

Intrapartum fever (>38°C) is associated with adverse maternal and neonatal outcomes. However, the correlation between low-grade fever (37.5°C-37.9°C) and adverse perinatal outcomes remains controversial.

OBJECTIVE

This study aimed to compare maternal and neonatal outcomes of women with prolonged rupture of membranes (≥12 hours) at term between those with low-grade fever and those with normal body temperature.

STUDY DESIGN

This retrospective study included women hospitalized in a tertiary university-affiliated hospital between July 2021 and May 2023 with singleton term and rupture of membranes ≥12 hours. Women were classified as having intrapartum low-grade fever (37.5°C-37.9°C) or normal body temperature (<37.5°C). The co-primary outcomes, postpartum endometritis and neonatal intensive care unit admission rates, were compared between these groups. The secondary maternal outcomes were intrapartum leukocytosis (>15,000/mm2), cesarean delivery rate, postpartum hemorrhage, postpartum fever, surgical site infection, and postpartum length of stay. The secondary neonatal outcomes were early-onset sepsis, 5-minute Apgar score of <7, umbilical artery cord pH<7.2 and pH<7.05, neonatal intensive care unit admission length of stay, and respiratory distress. The data were analyzed according to rupture of membranes 12 to 18 hours and rupture of membranes ≥18 hours. In women with rupture of membranes ≥18 hours, intrapartum ampicillin was administered, and chorioamniotic membrane swabs were obtained. The likelihood ratios and 95% confidence intervals were calculated for the co-primary outcomes. A multivariate logistic regression model was used to predict puerperal endometritis controlled for rupture of membranes duration, low-grade fever (compared with normal body temperature), positive group B streptococcus status, mechanical cervical ripening, cervical ripening by prostaglandins, artificial rupture of membranes, meconium staining, epidural analgesia, and cesarean delivery. A multivariate logistic regression model was used to predict neonatal intensive care unit admission controlled for rupture of membranes duration, low-grade fever, positive group B streptococcus status, mechanical cervical ripening, artificial rupture of membranes, meconium staining, cesarean delivery, and neonatal weight of <2500 g.

RESULTS

This study included 687 women with rupture of membranes 12 to 18 hours and 1109 with rupture of membranes ≥18 hours. In both latency groups, the rates were higher for cesarean delivery, endometritis, surgical site infections, umbilical cord pH<7.2, neonatal intensive care unit admission, and sepsis workup among those with low-grade fever than among those with normal body temperature. Among women with low-grade fever, the positive likelihood ratios were 12.7 (95% confidence interval, 9.6-16.8) for puerperal endometritis and 3.2 (95% confidence interval, 2.0-5.3) for neonatal intensive care unit admission. Among women with rupture of membranes ≥18 hours, the rates were higher of Enterobacteriaceae isolates in chorioamniotic membrane cultures for those with low-grade fever than for those with normal intrapartum temperature (22.0% vs 11.0%, respectively; P=.006). Low-grade fever (odds ratio, 9.0; 95% confidence interval, 3.7-21.9; P<.001), artificial rupture of membranes (odds ratio, 4.2; 95% confidence interval, 1.5-11.7; P=.007), and cesarean delivery (odds ratio, 5.4; 95% confidence interval, 2.2-13.4; P<.001) were independently associated with puerperal endometritis. Low-grade fever (odds ratio, 3.2; 95% confidence interval, 1.7-6.0; P<.001) and cesarean delivery (odds ratio, 1.9; 95% confidence interval, 1.1-13.1; P=.023) were independently associated with neonatal intensive care unit admission.

CONCLUSION

In women with rupture of membranes ≥12 hours at term, higher maternal and neonatal morbidities were reported among those with low-grade fever than among those with normal body temperature. Low-grade fever was associated with a higher risk of Enterobacteriaceae isolates in chorioamniotic membrane cultures. Moreover, low-grade fever may be the initial presentation of peripartum infection.

Exposures during pregnancy and at birth are associated with the risk of offspring eating disorders

BACKGROUND

Eating disorders (ED) are severe psychiatric disorders, commonly debuting early. Aberrances in the intrauterine environment and at birth have been associated with risk of ED. Here, we explore if, and at what effect size, a variety of such exposures associate with offspring ED, that is, anorexia nervosa (AN), bulimia nervosa (BN), and eating disorder not otherwise specified (EDNOS).

METHODS

This population-based cohort study, conducted from September 2021 to August 2023, used Finnish national registries of all live births in 1996-2014 (N = 1,097,753). Cox proportional hazards modeling was used to compare ED risk in exposed versus unexposed offspring, adjusting for potential confounders and performing sex-stratified analyses.

RESULTS

A total of 6614 offspring were diagnosed with an ED; 3668 AN, 666 BN, and 4248 EDNOS. Lower risk of offspring AN was seen with young mothers, continued smoking, and instrumental delivery, while higher risk was seen with older mothers, inflammatory disorders, prematurity, small for gestational age, and low Apgar. Offspring risk of BN was higher with continued smoking and prematurity, while lower with postmature birth. Offspring risk of EDNOS was lower with instrumental delivery, higher for older mothers, polycystic ovary syndrome, insulin-treated pregestational diabetes, antibacterial treatment, prematurity, and small for gestational age. Sex-specific associations were found.

CONCLUSIONS

Several prenatal and at birth exposures are associated with offspring ED; however, we cannot exclude confounding by maternal BMI. Nevertheless, several exposures selectively associate with risk of either AN, BN, or EDNOS, and some are sex-specific, emphasizing the importance of subtype- and sex-stratified analyses of ED.

PUBLIC SIGNIFICANCE

We define environmental factors involved in the development of different ED, of importance as preventive measure, but also in order to aid in defining the molecular pathways involved and thus in the longer perspective contribute to the development of pharmacological treatment of ED.

Grand multiparity, is it a help or a hindrance in a trial of labor after cesarean section (TOLAC)?

OBJECTIVE

Parity is a prognostic variable when considering trial of labor after cesarean section (TOLAC). This study aimed to determine whether grandmultiparous patients are at increased risk of poor TOLAC outcomes such as uterine rupture.

STUDY DESIGN

A retrospective cohort was conducted at a single university-affiliated medical center with approximately 10,000 deliveries per year. The study group included women post one cesarean section who attempted TOLAC carrying a singleton fetus in vertex presentation. We divided the cohort into three groups: group 1 - women who had a parity of 1; group 2 - parity of 2-4; group 3 - parity of 5 and above. The primary outcome was successful VBAC. Secondary outcomes included mode of delivery, uterine rupture, and combined maternal and neonatal adverse outcomes. Data were analyzed using Fisher's exact test, Chi-square test, ANOVA, and paired t-test.

RESULTS

Five thousand four hundred and forty-seven women comprised the study group: group 1 - 879 patients, group 2 - 2374 patients, and group 3 - 2194 patients. No significant between-group differences were found in gestational age at delivery. Rates of a successful VBAC were 80.6%, 95.4%, and 95.5%, respectively. Group 1 were more likely to have a failed TOLAC compared to group 2 (OR 5.02, 95% CI 3.9-6.5, p<.001) and group 3 (OR 5.17, 95% CI 4.0-6.7, p<.001). There was no increased risk of failed TOLAC when comparing groups 2 and 3 (OR 1.03; 95% CI 0.8-1.4, p=.89). Operative delivery rate differed significantly between all three groups; 25.1%, 6.2%, and 3.6%, for groups 1, 2, and 3, respectively (p<.001). The rate of uterine rupture was significantly higher in group 1 compared to group 2 (1.02% vs. 0.29% p=.02) and group 3 (1.02% vs. 0.2%, p=.01, respectively). There were no differences between group 2 and group 3 (0.29% vs. 0.2% p=.78).

CONCLUSIONS

Grandmultiparity is not associated with an increased risk of uterine rupture during TOLAC.

Epidural analgesia and emergency delivery: exploring causal misconceptions

Linked article: This Correspondence comments on Tabernée Heijtmeijer et al. Click here to view the article.

Should we use composite outcomes in obstetric clinical prediction models?

Clinical prediction models assist clinicians to estimate the natural course of a condition, and thus facilitate treatment decisions. The development of prediction models is increasingly common in obstetric research. Composite outcomes, whereby multiple outcomes are combined into a single endpoint, are frequently used in obstetric prediction models to increase statistical power when predicting rare events. Although existing literature has reviewed the positives and negatives of using composite outcomes in clinical trials, there has been minimal commentary on the implications of their use in the development and reporting of prognostic models. In this article, we review these issues, in particular, highlighting how unequal individual relationships between predictors and individual component outcomes can result in misleading conclusions, which may result in the omission of important but rare predictors or inappropriately inform clinical decisions to implement an intervention. We propose careful use, or where possible avoidance, of composite outcomes in the development of prognostic models in obstetrics. Methodological standards for developing prognostic models should be updated to standardise and appraise composite outcomes when their use is necessary. We also support previous recommendations to report on the accuracy of key components and inconsistencies among predictor variables.

Minimum sample size for developing a multivariable prediction model using multinomial logistic regression

AIMS

Multinomial logistic regression models allow one to predict the risk of a categorical outcome with > 2 categories. When developing such a model, researchers should ensure the number of participants (n ) is appropriate relative to the number of events (E k ) and the number of predictor parameters (p k ) for each category k. We propose three criteria to determine the minimum n required in light of existing criteria developed for binary outcomes.

PROPOSED CRITERIA

The first criterion aims to minimise the model overfitting. The second aims to minimise the difference between the observed and adjusted R 2 Nagelkerke. The third criterion aims to ensure the overall risk is estimated precisely. For criterion (i), we show the sample size must be based on the anticipated Cox-snell R 2 of distinct 'one-to-one' logistic regression models corresponding to the sub-models of the multinomial logistic regression, rather than on the overall Cox-snell R 2 of the multinomial logistic regression.

EVALUATION OF CRITERIA

We tested the performance of the proposed criteria (i) through a simulation study and found that it resulted in the desired level of overfitting. Criterion (ii) and (iii) were natural extensions from previously proposed criteria for binary outcomes and did not require evaluation through simulation.

SUMMARY

We illustrated how to implement the sample size criteria through a worked example considering the development of a multinomial risk prediction model for tumour type when presented with an ovarian mass. Code is provided for the simulation and worked example. We will embed our proposed criteria within the pmsampsize R library and Stata modules.

Are levator hiatal dimensions in mid-pregnancy associated with mode of delivery?

INTRODUCTION AND HYPOTHESIS

Slow progress of labour is a risk for operative delivery. Smaller levator hiatal dimensions are possible risk factors for slow progress and operative delivery. Our aim was to explore associations between hiatal dimensions antenatally, duration of second stage of labour and mode of delivery.

METHODS

Prospective cohort study of 65 nullipara examined at 20 weeks gestation and 6 months postpartum. Levator hiatal anteroposterior diameter and area were measured using 2D/3D transperineal ultrasound and compared between women with normal vaginal delivery and operative delivery (vacuum or caesarean) using t-test and with Spearman's rank to explore correlations with duration of second stage. ROC analysis established a cut-off for high risk of operative delivery.

RESULTS

Two-dimensional anteroposterior diameter and 3D hiatal area at rest were smaller in women with operative delivery than with normal delivery, 5.0 cm vs. 5.7 cm, p = 0.007 and 18.5 cm² vs. 14.9 cm², p < 0.001. From the ROC curve for 2D anteroposterior diameter, a cut-off of 5.6 cm, (sensitivity = 0.94, specificity = 0.63) and for 3D hiatal area a cut-off of 17.6 cm² (sensitivity = 0.94, specificity = 0.65) predicted operative delivery. We found inverse correlations between second stage of labour and anteroposterior diameter at rest, r = -0.330, contraction, r = -0.365, area at rest, r = -0.324, and contraction, r = -0.521, all p < 0.05.

CONCLUSIONS

Smaller hiatal dimensions at 20 weeks gestation were associated with longer second stage of labour and increased risk of operative delivery in nullipara. A 2D anteroposterior hiatal diameter < 5.6 cm and 3D hiatal area < 17.6 cm² at rest imply increased risk of operative delivery.

Association between screening for antenatal depressive symptoms and delivery outcomes: The Born in Queensland Study

BACKGROUND

Evidence shows that depressive symptoms during pregnancy increase the risk of an intervention during delivery (induction, the use of forceps or vacuum, and caesarean sections (CS)). Many women with depression during pregnancy are not identified and therefore will not receive appropriate follow up of their symptoms. We hypothesised that routine screening for depressive symptoms during pregnancy could reduce detrimental consequences of depressive symptoms on delivery outcomes.

AIM

We explored the association between screening for depressive symptoms during pregnancy and delivery outcomes.

MATERIALS AND METHODS

A cross-sectional analysis of state-wide administrative data sets. The population included all women who delivered a singleton in Queensland between the July and December of 2015. Logistic regression analyses were run in 27 501 women (93.1% of the total population) with information in all variables. The following were the main outcomes: onset of labour, CS, instrumental vaginal delivery, and all operative deliveries (including both CS and instrumental vaginal deliveries).

RESULTS

Women who completed the screening had increased odds of a spontaneous onset of labour (adjusted odds ratio (aOR) 1.18; 95% CI 1.09-1.27) and decreased odds of an operative delivery (instrumental or CS) (aOR 0.88; 95% CI 0.81-0.96). Among women who had a vaginal delivery, those who completed the screening had decreased odds of having an instrumental delivery (aOR 0.84; 95% CI 0.74-0.97). Sensitivity analyses in women who did not have a formal diagnosis of depression showed similar results.

CONCLUSION

Our findings suggest that screening may decrease interventions during delivery in women with depressive symptoms.

Accuracy of approximations to recover incompletely reported logistic regression models depended on other available information

OBJECTIVE

To provide approximations to recover the full regression equation across different scenarios of incompletely reported prediction models that were developed from binary logistic regression.

STUDY DESIGN AND SETTING

In a case study, we considered four common scenarios and illustrated their corresponding approximations: (A) Missing: the intercept, Available: the regression coefficients of predictors, overall frequency of the outcome and descriptive statistics of the predictors; (B) Missing: regression coefficients and the intercept, Available: a simplified score; (C) Missing: regression coefficients and the intercept, Available: a nomogram; (D) Missing: regression coefficients and the intercept, Available: a web calculator.

RESULTS

In the scenario A, a simplified approach based on the predicted probability corresponding to the average linear predictor was inaccurate. An approximation based on the overall outcome frequency and an approximation of the linear predictor distribution was more accurate, however, the appropriateness of the underlying assumptions cannot be verified in practice. In the scenario B, the recovered equation was inaccurate due to rounding and categorization of risk scores. In the scenarios C and D, the full regression equation could be recovered with minimal error.

CONCLUSION

The accuracy of the approximations in recovering the regression equation varied depending on the available information.

Nomogram predicting cesarean delivery undergoing induction of labor among high-risk nulliparous women at term: a retrospective study

Background

Our aim was to create and validate a nomogram predicting cesarean delivery after induction of labor among nulliparous women at term.

Methods

Data were obtained from medical records from Nanjing Drum Tower Hospital. Nulliparous women with singleton pregnancies undergoing induction of labor at term were involved. A total of 2950 patients from Jan. 2014 to Dec. 2015 were served as derivation cohort. A nomogram was constructed by multivariate logistic regression using maternal, fetal and pregnancy characteristics. The predictive accuracy and discriminative ability of the nomogram were internal validated by 1000-bootstrap resampling, followed by external validation of a new dataset from Jan. 2016 to Dec. 2016.

Results

Logistic regression revealed nine predictors of cesarean delivery, including maternal height, age, uterine height, abdominal circumference, estimated fetal weight, indications for induction of labor, initial cervical consistency, cervical effacement and station. Nomogram was well calibrated and had an AUC of 0.73 (95% confidence interval [CI], 0.70-0.75) after bootstrap resampling for internal validation. The AUC in external validation reached 0.67, which was significantly higher than that of three models published previously (P<0.05).

Conclusions

This validated nomogram, constructed by variables that were obtained form medical records, can help estimate risk of cesarean delivery before induction of labor.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12884-022-04386-8.

Does antenatal depression predict post-partum depression and obstetric complications? Results from a longitudinal, long-term, real-world study

BACKGROUND

Main aims of the present paper are to: (1) assess the prevalence of antenatal depression (AD) and identify its predictors; (2) analyse the impact of AD on obstetric outcomes and on the incidence of post-partum depression.

METHODS

All pregnant women referring to the Gynecology and Obstetrics inpatients unit of the University of Campania "Luigi Vanvitelli" were invited to participate. Upon acceptance, women completed the Italian version of the Edinburgh Postnatal Depression Scale and an ad-hoc questionnaire on the women's sociodemographic, gynecological and peripartum characteristics as well as their psychiatric history. Women were assessed at each trimester of pregnancy, immediately after the childbirth and after one, three, 6 and 11 months.

RESULTS

268 pregnant women were recruited, with a mean of 32.2 (±5.81) years. Ninety-seven women (36.2%) reported the presence of depressive symptoms during pregnancy. Predictors of AD were personal history of depression, a family history for depressive disorders and problematic relationships with the partner. The presence of AD was associated to a reduced gestational age at the time of delivery, a lower APGAR score at 1 and 5 min, labor induction and admission of the new-born into neonatal intensive care unit. Mothers with antenatal depression are less likely to natural breastfeed. Lastly, antenatal depression was a risk factor for higher EPDS scores at follow-ups.

CONCLUSIONS

Our results support the idea that women should be screened during pregnancy and post-partum for the presence of depressive and anxiety symptoms. Health professionals should be adequately trained to detect psychiatric symptoms during pregnancy.

The impact of levothyroxine exposure on delivery outcome in hypothyroid pregnant women (PETAL study): A five-year retrospective cohort study

Background

Hypothyroidism affects 3% of pregnant women, and to date, no studies have addressed the impact levothyroxine-treated hypothyroidism on delivery outcome.

Methods

This retrospective cohort study was conducted among 750 women with a singleton pregnancy who gave birth between 2015 and 2019. Delivery modes were compared between 250 hypothyroid women exposed to levothyroxine and 500 euthyroid control women. The aim of this study was to determine the impact of levothyroxine exposure on delivery outcome.

Results

Multiple logistic regression showed no significant association between exposure to levothyroxine and the overall rate of caesarean delivery (aOR 1.1; 95% CI 0.8 to 1.6). Mean TSH concentrations were significantly higher throughout the pregnancy in hypothyroid women despite levothyroxine treatment. Maternal and neonatal outcomes in both groups were not different.

Conclusion

Hypothyroidism treated with levothyroxine during pregnancy according to local guidelines is not a significant risk factor for caesarean delivery.

Customized Probability of Vaginal Delivery With Induction of Labor and Expectant Management in Nulliparous Women at 39 Weeks of Gestation

OBJECTIVE

To develop models to predict vaginal delivery in low-risk, nulliparous women contemplating elective induction of labor or expectant management at 39 weeks of gestation.

METHODS

We conducted a secondary analysis of a randomized controlled trial of planned elective induction of labor at 39 weeks of gestation compared with expectant management for low-risk nulliparous women. Two groups were included for this analysis: 1) women who were randomized to the induction of labor group and underwent elective induction at 39 0/7-39 4/7 weeks of gestation and 2) women who were randomized to the expectant management group who experienced spontaneous labor or medically indicated delivery (including postterm). Multivariable logistic regression models were developed for each group using patient characteristics that would be available at the time of counseling. Model selection was based on k-fold cross-validation using backward elimination and variables that remained significant at P<.05 were retained. To compare estimated with observed rates, the elective induction of labor model was then applied to each woman in both groups to estimate individualized predicted probabilities of vaginal delivery with elective induction of labor.

RESULTS

Of 6,106 women enrolled in the trial, 4,661 met criteria for this analysis. Vaginal delivery occurred in 80.6% of the 2,153 women in the elective induction of labor group and 77.2% of the 2,508 women in the expectant management group (P=.005). The final elective induction of labor model included age, height, weight, and modified Bishop score (area under the receiver operating characteristic curve [AUROC] 0.72, 95% CI 0.70-0.75). The same variables were included in the final expectant management model (AUROC 0.70, 95% CI 0.67-0.72). Across the range of predicted probability deciles derived from the elective induction of labor model, almost all women who underwent elective induction of labor at 39 weeks of gestation had a higher observed chance of vaginal delivery than expectant management.

CONCLUSION

Irrespective of the individual predicted chance of vaginal delivery from elective induction of labor at 39 weeks of gestation, vaginal delivery is generally more frequent if elective induction of labor is undertaken rather than expectant management. These data can be used to counsel nulliparous women regarding their "customized" chances of vaginal delivery as they choose between elective induction of labor or expectant management at 39 weeks of gestation.

CLINICAL TRIAL REGISTRATION

ClinicalTrials.gov, NCT01990612.

Determinants of length of stay after cesarean sections in the Friuli Venezia Giulia Region (North-Eastern Italy), 2005-2015

Since Italy has the highest cesarean section (CS) rate (38.1%) among all European countries, the containment of health care costs associated with CS is needed, along with control of length of hospital stay (LOS) following CS. This population based cross-sectional study aims to investigate LoS post CS (overall CS, OCS; planned CS, PCS; urgent/emergency CS, UCS), in Friuli Venezia Giulia (a region of North-Eastern Italy) during 2005–2015, adjusting for a considerable number factors, including various obstetric conditions/complications. Maternal and newborn characteristics (health care setting and timeframe; maternal health factors; child’s size factors; child’s fragility factors; socio-demographic background; obstetric history; obstetric conditions) were used as independent variables. LoS (post OCS, PCS, UCS) was the outcome measure. The statistical analysis was conducted with multivariable linear (LoS expressed as adjusted mean, in days) as well as logistic (adjusted proportion of LoS > 4 days vs. LoS ≤ 4 days, using a 4 day cutoff for early discharge, ED) regression. An important decreasing trend over time in mean LoS and LoS > ED was observed for both PCS and UCS. LoS post CS was shorter with parity and history of CS, whereas it was longer among non-EU mothers. Several obstetric conditions/complications were associated with extended LoS. Whilst eclampsia/pre-eclampsia and preterm gestations (33–36 weeks) were predominantly associated with longer LoS post UCS, for PCS LoS was significantly longer with birthweight 2.0–2.5 kg, multiple birth and increasing maternal age. Strong significant inter-hospital variation remained after adjustment for the major clinical conditions. This study shows that routinely collected administrative data provide useful information for health planning and monitoring, identifying inter-hospital differences that could be targeted by policy interventions aimed at improving the efficiency of obstetric care. The important decreasing trend over time of LoS post CS, coupled with the impact of some socio-demographic and obstetric history factors on LoS, seemingly suggests a positive approach of health care providers of FVG in decision making on hospitalization length post CS. However, the significant role of several obstetric conditions did not influence hospital variation. Inter-hospital variations of LoS could depend on a number of factors, including the capacity to discharge patients into the surrounding non-acute facilities. Further studies are warranted to ascertain whether LoS can be attributed to hospital efficiency rather than the characteristics of the hospital catchment area.

Clinical prediction models to predict the risk of multiple binary outcomes: a comparison of approaches

Clinical prediction models (CPMs) can predict clinically relevant outcomes or events. Typically, prognostic CPMs are derived to predict the risk of a single future outcome. However, there are many medical applications where two or more outcomes are of interest, meaning this should be more widely reflected in CPMs so they can accurately estimate the joint risk of multiple outcomes simultaneously. A potentially naïve approach to multi-outcome risk prediction is to derive a CPM for each outcome separately, then multiply the predicted risks. This approach is only valid if the outcomes are conditionally independent given the covariates, and it fails to exploit the potential relationships between the outcomes. This paper outlines several approaches that could be used to develop CPMs for multiple binary outcomes. We consider four methods, ranging in complexity and conditional independence assumptions: namely, probabilistic classifier chain, multinomial logistic regression, multivariate logistic regression, and a Bayesian probit model. These are compared with methods that rely on conditional independence: separate univariate CPMs and stacked regression. Employing a simulation study and real-world example, we illustrate that CPMs for joint risk prediction of multiple outcomes should only be derived using methods that model the residual correlation between outcomes. In such a situation, our results suggest that probabilistic classification chains, multinomial logistic regression or the Bayesian probit model are all appropriate choices. We call into question the development of CPMs for each outcome in isolation when multiple correlated or structurally related outcomes are of interest and recommend more multivariate approaches to risk prediction.

Explanatory variables and nomogram of a clinical prediction model to estimate the risk of caesarean section after term induction

The aims of this study were to identify the explanatory variables associated with failure of induction of labour (IOL) and to designate nomograms that predict probability. This retrospective study included 1328 singleton term pregnant women (37-42 weeks). The penalised maximum likelihood estimation (PMLE) method was used instead of traditional logistic regression. Of the 25,678 deliveries that occurred during the study period, 1328 (5.1%) women underwent term delivery. Of those, 1125 (84.7%) had successful vaginal deliveries and 203 (15.3%) had failed vaginal deliveries following use of a dinoprostone slow-release vaginal insert. Explanatory variables were discovered that were associated with delivery failure in term pregnancy undergoing induction of labour with an unfavourable cervix, and a nomogram that predicted probability was developed.IMPACT STATEMENTWhat is already known on this subject? The caesarean rate has continued to climb worldwide over the past decade. Most caesarean sections are performed because of suspected foetal distress or failure to progress. In absolute numbers, most caesarean deliveries are performed in women with a term pregnancy with a foetus in cephalic presentation. Despite these numbers, predicting the mode of delivery by which these women will deliver remains a challenge.What do the results of this study add? Five explanatory variables were strongly associated with failure of dinoprostone delivery of term pregnancies: nulliparity, induction time, premature rupture of membranes, Bishop score and foetal genderWhat are the implications of these findings for clinical practice and further research? The developed nomograms enable fast and easy implementation in clinical practice. After external validation and proof of generalisability, the present model could be used in obstetric clinical management.

Radiomics Nomogram for Prediction of Peritoneal Metastasis in Patients With Gastric Cancer

Objective: The aim of this study is to evaluate whether radiomics imaging signatures based on computed tomography (CT) could predict peritoneal metastasis (PM) in gastric cancer (GC) and to develop a nomogram for preoperative prediction of PM status.

Methods: We collected CT images of pathological T4 gastric cancer in 955 consecutive patients of two cancer centers to analyze the radiomics features retrospectively and then developed and validated the prediction model built from 292 quantitative image features in the training cohort and two validation cohorts. Lasso regression model was applied for selecting feature and constructing radiomics signature. Predicting model was developed by multivariable logistic regression analysis. Radiomics nomogram was developed by the incorporation of radiomics signature and clinical T and N stage. Calibration, discrimination, and clinical usefulness were used to evaluate the performance of the nomogram.

Results: In training and validation cohorts, PM status was associated with the radiomics signature significantly. It was found that the radiomics signature was an independent predictor for peritoneal metastasis in multivariable logistic analysis. For training and internal and external validation cohorts, the area under the receiver operating characteristic curves (AUCs) of radiomics signature for predicting PM were 0.751 (95%CI, 0.703–0.799), 0.802 (95%CI, 0.691–0.912), and 0.745 (95%CI, 0.683–0.806), respectively. Furthermore, for training and internal and external validation cohorts, the AUCs of radiomics nomogram for predicting PM were 0.792 (95%CI, 0.748–0.836), 0.870 (95%CI, 0.795–0.946), and 0.815 (95%CI, 0.763–0.867), respectively.

Conclusions: CT-based radiomics signature could predict peritoneal metastasis, and the radiomics nomogram can make a meaningful contribution for predicting PM status in GC patient preoperatively.

Is mode of first birth a risk factor for subsequent preterm birth?

BACKGROUND

Previous preterm birth is a strong predictor of subsequent preterm birth, but less is known about the causes of preterm birth following a full-term first pregnancy. Recent research has highlighted previous caesarean section as a potential risk factor.

AIM

To examine the relationship between mode of first birth and the risk of subsequent preterm birth in New South Wales (NSW), Australia.

MATERIALS AND METHODS

A population-based record-linkage study of NSW women who had a live singleton first birth at ≥37 weeks gestation, followed by a singleton second birth between 2005 and 2017. Relative risk (RR) and 95% CI of preterm birth in the subsequent pregnancy was calculated using modified Poisson regression, with mode of first birth as the exposure. Spontaneous preterm birth and preterm prelabour caesarean were secondary outcomes.

RESULTS

Women who had either an intrapartum (RR: 1.26, 95% CI 1.19-1.32) or prelabour caesarean (RR: 1.26, 95% CI 1.18-1.35) first birth had a higher risk of subsequent preterm birth (any birth <37 weeks gestation), than those who birthed vaginally. Women who had a previous instrumental birth (RR: 0.85, 95% CI 0.79-0.91) or prelabour caesarean (RR: 0.74, 95% CI 0.67-0.82) had lower risks of subsequent spontaneous preterm birth. However, prior prelabour caesarean also greatly increased risk of subsequent preterm prelabour caesarean (RR: 5.25, 95% CI 4.65-5.93).

CONCLUSIONS

The mode of first birth has differing effects on the risk of subsequent spontaneous preterm birth and preterm prelabour caesarean. Awareness of the risk of subsequent preterm birth following caesarean section may help inform clinical decisions around mode of first birth.

Predictor variables in the success of slow-release dinoprostone used for cervical ripening in intrauterine growth restriction pregnancies

OBJECTIVE

This study aims to evaluate the consequences of a trigger by vaginal Dinoprotone on outcome of pregnancies with Intrauterine growth restriction (IUGR).

MATERIALS AND METHODS

This retrospective study included 161 induced IUGR fetuses (35-39 weeks). Consecutive patients who were evaluated formed the basis of the clinical outcomes. The penalized maximum likelihood estimation (PMLE) method was used instead of traditional logistic regression in order to reduce the risk of overfitting.

RESULTS

Of the 25,678 deliveries that occurred during the study period, 161 (0.6%) women underwent IUGR delivery; of these, 117 (73%) succeeded and 44 (27%) failed to achieve cervical ripening using the dinoprostone slow-release vaginal insert. Two predictors were associated with dinoprostone vaginal delivery success: Parity (OR:1.4([0.89-2.3]), and Bishop score (OR:1.54[1.23-1.94]). The PMLE model correctly classified 78% participants (c-index: 0.78).

CONCLUSION

Basic parameters such as parity and Bishop score can be used to predict successful vaginal birth following dinoprostone slow-release vaginal insert administration.

Can the Progression Angle before Labor Help to Predict Cesarean Section?

OBJECTIVE

The aim of this study was to predict cesarean section on a single visit at term using a combination of maternal history and ultrasound markers, including some new markers such as the progression angle used to assess intrapartum progress.

STUDY DESIGN

This was an observational prospective cohort study of singleton term pregnancies that included 575 women. The maternal history and ultrasound markers were obtained on a single visit at 37-38 weeks' gestation. Multivariable logistic regression was used for prediction of cesarean section.

RESULTS

Five hundred and seventy-five women were examined at a median gestational age of 38.3 weeks (range: 35.6-41.6) and a cesarean section was performed on 104 women (18%) - 24 for a fetal indication and 80 for a maternal indication. The risk of cesarean section increased with a previous cesarean section, assisted reproduction techniques, a higher estimated fetal weight, and a greater cervical length, and decreased with a greater maternal height, multiparity, and a wider progression angle. The detection rate for a 20% false positive rate was 69.9% for all cesarean sections, 54.2% for those with a fetal indication, and 77.2% for those with a maternal indication.

CONCLUSIONS

Assessment at 37-38 weeks' gestation of ultrasound markers such as the cervical length, progression angle, and estimated fetal weight, in combination with the maternal history, can predict a cesarean section in labor. Cesarean section for a maternal indication is better predicted than cesarean section for a fetal indication.

Development of a cross-validated model for predicting emergency cesarean for intrapartum fetal compromise at term

OBJECTIVES

To develop a model for predicting emergency cesarean for fetal distress (ECFD) at term using a combination of maternal and late pregnancy ultrasound parameters measured at more than 36 gestational weeks.

METHODS

A study of prospectively collected data, including ultrasound scans at 36-38 weeks, for singleton non-anomalous deliveries at Mater Mother's Hospital, Brisbane, Australia, between January 2010 and April 2017. Univariable and multivariable mixed-effects generalized linear models were generated. The final model was validated by the K-fold cross validation technique.

RESULTS

Overall, 5439 women met the inclusion criteria; of these, 230 (4.2%) underwent ECFD. There were more nulliparous women and women with induction of labor (IOL) in the ECFD cohort (both P < 0.001). ECFD neonates had lower z-scores for estimated fetal weight (EFW), cerebroplacental ratio (CPR), and middle cerebral artery pulsatility index; and higher scores for umbilical artery pulsatility index. Ethnicity, nulliparity, IOL, EFW z-score, and CPR z-score were included in the final prediction model, which showed high accuracy with an area under the receiver operator characteristic curve of 0.77.

CONCLUSION

The study shows that a prediction model combining the continuous standardized measures of CPR and EFW and several maternal factors was able to identify ECFD with improved accuracy.

Echogenicity of puborectalis muscle, cervix and vastus lateralis muscle in pregnancy in relation to mode of delivery

OBJECTIVES

To confirm our previous observation that levator hiatal dimensions and mean echogenicity of the puborectalis muscle (MEP) are significantly different at 12 weeks' gestation in women who delivered by Cesarean section due to failure to progress compared with those who delivered vaginally. The secondary objective was to assess the association between the echogenicity of the cervix and vastus lateralis muscle and mode of delivery.

METHODS

In this prospective multicenter study, 306 nulliparous women with a singleton pregnancy underwent ultrasound assessments of the pelvic floor at rest, on maximum pelvic floor muscle contraction and on maximum Valsalva maneuver, of the cervix and of the vastus lateralis muscle at 12 weeks' gestation. Dimensions of the levator hiatus, MEP and mean echogenicity of the cervix and vastus lateralis muscle were measured and compared according to mode of delivery.

RESULTS

Two hundred and forty-nine women were included in the analyses. We were unable to confirm our previous finding that MEP and levator hiatal transverse diameter and area at 12 weeks' gestation are associated significantly with mode of delivery. In addition, we could not demonstrate a significant association between echogenicity of the cervix or vastus lateralis muscle and mode of delivery. Overall, MEP was a mean of 20 points lower in women in the new database as compared with the previous study, despite the use of the same ultrasound equipment.

CONCLUSION

In a second, independent multicenter dataset, we were unable to confirm our previous finding that levator hiatal dimensions and MEP on pelvic floor muscle contraction are associated significantly with mode of delivery. We also found no association between echogenicity of the cervix or vastus lateralis and mode of delivery. Copyright © 2018 ISUOG. Published by John Wiley & Sons Ltd.

Radiomics Signature on Computed Tomography Imaging: Association With Lymph Node Metastasis in Patients With Gastric Cancer

Background: To evaluate whether radiomic feature-based computed tomography (CT) imaging signatures allow prediction of lymph node (LN) metastasis in gastric cancer (GC) and to develop a preoperative nomogram for predicting LN status.

Methods: We retrospectively analyzed radiomics features of CT images in 1,689 consecutive patients from three cancer centers. The prediction model was developed in the training cohort and validated in internal and external validation cohorts. Lasso regression model was utilized to select features and build radiomics signature. Multivariable logistic regression analysis was utilized to develop the model. We integrated the radiomics signature, clinical T and N stage, and other independent clinicopathologic variables, and this was presented as a radiomics nomogram. The performance of the nomogram was assessed with calibration, discrimination, and clinical usefulness.

Results: The radiomics signature was significantly associated with pathological LN stage in training and validation cohorts. Multivariable logistic analysis found the radiomics signature was an independent predictor of LN metastasis. The nomogram showed good discrimination and calibration.

Conclusions: The newly developed radiomic signature was a powerful predictor of LN metastasis and the radiomics nomogram could facilitate the preoperative individualized prediction of LN status.

Sample size considerations and predictive performance of multinomial logistic prediction models

Multinomial Logistic Regression (MLR) has been advocated for developing clinical prediction models that distinguish between three or more unordered outcomes. We present a full‐factorial simulation study to examine the predictive performance of MLR models in relation to the relative size of outcome categories, number of predictors and the number of events per variable. It is shown that MLR estimated by Maximum Likelihood yields overfitted prediction models in small to medium sized data. In most cases, the calibration and overall predictive performance of the multinomial prediction model is improved by using penalized MLR. Our simulation study also highlights the importance of events per variable in the multinomial context as well as the total sample size. As expected, our study demonstrates the need for optimism correction of the predictive performance measures when developing the multinomial logistic prediction model. We recommend the use of penalized MLR when prediction models are developed in small data sets or in medium sized data sets with a small total sample size (ie, when the sizes of the outcome categories are balanced). Finally, we present a case study in which we illustrate the development and validation of penalized and unpenalized multinomial prediction models for predicting malignancy of ovarian cancer.

Changes in intrapartum maternal placental growth factor levels in pregnancies complicated by fetal compromise at term

BACKGROUND

Intrapartum fetal compromise (IFC) may result from the gradual decline in placental function during labour and can precipitate adverse neonatal outcomes. Placental growth factor (PlGF) is a biomarker of placental function. This study aims to investigate maternal PlGF levels and adverse perinatal outcomes in term labour.

METHODS

Prospective observational study (Mater Mothers' Hospital, Brisbane). Eligibility: 37⁺⁰- 42⁺⁰ weeks gestation, singleton, cephalic, non-anomalous pregnancies. Cases of pre-eclampsia and fetal growth restriction were excluded. Maternal PlGF was sampled at the onset of the first stage of labour (1st PlGF) and again at the second stage (2nd PlGF).

RESULTS

Sixty-three participants met inclusion criteria. Women requiring operative delivery (n = 11) for IFC had lower 1st PlGF (90.8 vs. 111.8 pg/ml) and 2nd PlGF (65.8 vs. 83.7 pg/ml) compared to the no-IFC cohort (n = 52). PlGF levels decreased significantly during labour in both the IFC (90.8 vs. 65.8 pg/ml, p = 0.021) and no-IFC (111.8 v 83.7, p < 0.001) cohorts, although the decline in PlGF levels was greater in the IFC cohort (-41.8% vs. -23.4%, p = 0.385). Maternal PlGF levels were significantly lower in those with an abnormal fetal heart rate pattern, cord arterial pH < 7.2, nursery admission and composite adverse neonatal outcome (CANO). PlGF decline was not correlated to duration of labour but was influenced by nulliparity and induced labour.

CONCLUSIONS

Maternal PlGF levels are lower in pregnancies complicated by IFC and CANO, and declines more sharply during labour compared to the no-IFC cohort. The utility of PlGF as a predictor of IFC should be further investigated with clinical trials.

Epidural Analgesia and Neonatal Morbidity: A Retrospective Cohort Study

(1) Background: Epidural analgesia (EA), at the present time, is one of the most effective methods to reduce labor pain. In recent years its use has increased, being used between 20–70% of all deliveries; (2) Methods: Historical cohort on a total of 2947 deliveries during the years 2012–2016 at the “Mancha-Centro Hospital” of Alcázar de San Juan. The main outcome variables were four neonatal morbidity (NM) criteria: umbilical artery pH of <7.10, Apgar score at 5 min < 7, need for advanced resuscitation and composite morbidity. We used the multivariate analysis to control confounding bias. (3) Results: No statistical relationship between EA and the second stage of labor duration with none of the four criteria of NM used (p > 0.005). However, the type of delivery was associated with three criteria (pH, resuscitation, and composite morbidity). The instrumental delivery presented an OR of pH < 7.10 of 2.68 95% CI [1.15, 6.27], an OR of advanced resuscitation of 2.44 95% CI [1.17, 5.08] and OR of composite morbidity of 2.86 95% CI [1.59, 5.12]; (4) Conclusions: The EA and the second stage of labor duration are not related to the NM. While the instrumental delivery doubles the risk of NM compared to the normal vaginal delivery.

A low fetal cerebroplacental ratio confers a greater risk of intrapartum fetal compromise and adverse neonatal outcomes in low risk multiparous women at term

BACKGROUND

A low fetal cerebroplacental ratio (CPR) and nulliparity have independently been shown to be associated with adverse obstetric and perinatal outcomes.

OBJECTIVES

To assess the effect of parity on the CPR and investigate the utility of a CPR threshold of <10^th centile for predicting adverse outcomes. We hypothesised that nulliparous women would have a lower CPR than multiparous women, impacting the diagnostic performance of the <10^th centile threshold. This is an important consideration for interpretation of a low CPR in clinical practice.

STUDY DESIGN

This was a retrospective cohort study of low risk, singleton pregnancies delivering at term in Australia's largest maternity hospital. The primary outcome was emergency caesarean section for intrapartum fetal compromise (EmCS IFC). Data was dichotomised according to parity and further by CPR <10^th centile. Multiple logistic regression was performed.

RESULTS

4737 women were included for analysis, 2333 were nulliparous and 2404 were multiparous. Overall the z-score (mean [SD])(CPR standardised for gestation) was lower in nulliparous compared to multiparous women (-0.16 [-1.73 - 1.42] vs 0.04 [-1.63 - 1.69], p < 0.001). Multiparous women had a non-significantly lower mean z-score for those who delivered by EmCS IFC than nulliparous women (-0.52 [-2.23 - 2.02] vs -0.45 [-2.22 - 1.1]). Nulliparous women had greater odds of having a CPR <10^th centile compared to the multiparous cohort (OR 1.24, 95% CI 1.02-1.5 vs. OR 0.81, 95% CI 0.7-0.98, p < 0.001). A CPR thresholdd <10^th centile in nulliparous women was associated with increased odds of intrapartum fetal compromise (IFC), EmCS IFC (aOR 1.72, 95CI 1.2-2.6, p < 0.05) and birthweight <10^th centile. A low CPR in multiparous women was associated with increased odds of all adverse perinatal outcomes measured: IFC, meconium stained liquor, EmCS IFC (aOR 4.99, 95%CI 2.5-9.9, p < 0.001), birthweight <10^th centile, acidosis, neonatal intensive care admission and severe composite neonatal outcome. These aORs were associated with specificities of >90% and false positive rates of <10% for all outcomes in multiparous women.

CONCLUSIONS

A CPR <10^th centile in multiparous women confers greater odds of adverse perinatal outcomes and as such of the influence of parity should be taken into account when decisions regarding clinical management are made because of a low CPR.

Blinded ultrasound fetal biometry at 36 weeks and risk of emergency Cesarean delivery in a prospective cohort study of low-risk nulliparous women

OBJECTIVES

To compare the association between risk of emergency Cesarean delivery (CD) and non-customized vs customized ultrasound estimated fetal weight (EFW) at 36 weeks' gestation, determine whether addition of ultrasound EFW to a model based on maternal characteristics alone improved prediction of emergency CD, assess the screening performance of a multivariable model using both EFW and maternal characteristics to predict emergency CD, and determine whether women at high predicted risk of emergency CD based on this model had higher risk of maternal and perinatal morbidity compared with screen-negative women.

METHODS

We studied 3047 low-risk (no pre-existing medical conditions or acquired complications of pregnancy) nulliparous women from the prospective Pregnancy Outcome Prediction study (Cambridge, UK) cohort, who underwent ultrasound EFW at ∼36 weeks' gestation. Both the women and their clinicians were blinded to fetal biometry results. Emergency CD was defined as delivery by Cesarean section in pregnancies in which the date of delivery had not been prearranged. Additional candidate predictors of emergency CD evaluated were maternal age, height, body mass index (BMI), weight gain, fetal abdominal circumference growth velocity and fetal sex. External validation of the predictive model was performed using routinely collected data from 55 337 births in Scotland between 2003 and 2008. Women with an estimated risk of emergency CD ≥ 40% were defined as screen positive.

RESULTS

Blinded EFW was associated strongly with the risk of emergency CD (coefficient for increase of 1 SD in EFW, 0.39 (95% CI, 0.30-0.48); odds ratio (OR), 1.48 (95% CI, 1.35-1.62)). The coefficient for customized EFW was similar (0.42 (95% CI, 0.33-0.51); OR, 1.53 (95% CI, 1.39-1.67)); hence, for simplicity, non-customized EFW was employed subsequently. A multivariable logistic regression model combining maternal characteristics (age, height, BMI and weight gain between 12 and 36 weeks) was moderately predictive of emergency CD (area under the receiver-operating characteristics curve (AUC) = 0.68). Addition of blinded EFW to the model increased the AUC to 0.71 and improved prediction (likelihood-ratio test P < 0.0001). Based on this model, 189 (6.2%) women were screen positive and 48% of these delivered by CD. Screen-positive women had elevated risks of severe postpartum hemorrhage (relative risk (RR), 2.49; 95% CI, 1.83-3.38), any adverse neonatal outcome (RR, 1.86; 95% CI, 1.22-2.82) and severe adverse neonatal outcome (RR, 4.03; 95% CI, 1.35-12.03) compared with screen-negative women. The risks of these events were also higher compared with women who had a term CD for breech presentation. The model was similarly predictive of the risk of emergency CD and perinatal morbidity when evaluated using the dataset from Scotland.

CONCLUSIONS

Ultrasound EFW at 36 weeks, combined with maternal characteristics, can identify women who are at increased risk of subsequent emergency CD. These women are at increased risk of maternal and perinatal morbidity compared with women at low risk of emergency CD and those having CD for breech presentation at term. Copyright © 2017 ISUOG. Published by John Wiley & Sons Ltd.

Is ultrasound measured fetal biometry predictive of intrapartum caesarean section for failure to progress?

BACKGROUND

There are global concerns regarding excessive caesarean rates, which could be reduced by identification of risk factors leading to preventative measures such as induction of labour.

AIMS

This study aims to describe the association between antenatal ultrasound and emergency caesarean section for: (i) failure to progress; (ii) other indications; and (iii) any indication.

MATERIALS AND METHODS

Women who had an ultrasound in pregnancy between 36^(+0/7) to 38^(+6/7) weeks at Royal Prince Alfred Hospital from January 2005 to June 2009 were included. Ultrasound parameters were linked to clinical parameters from the maternity database. Missing clinical data were imputed and multiple logistic regression performed.

RESULTS

Fetal biometry data were available for 2006 pregnancies. After adjusting for maternal age, height, body mass index, parity, previous caesarean section and diabetes, caesarean section for failure to progress was associated with estimated fetal weight (odds ratio (OR) 2.24 (95% CI: 1.76-2.84) per 500 g increase); or biparietal diameter (OR 1.51 (1.16-1.97) per 5 mm increase) and abdominal circumference (OR for the 4th quartile (>75th centile) compared with the 10-25th centile group was 2.09 (1.13-3.85)).* There were also non-linear associations between components of fetal biometry and caesarean section for fetal distress and for any indication.

CONCLUSIONS

Components of fetal biometry in the third trimester are associated with intrapartum caesarean section for failure to progress. These parameters could be incorporated into models to predict emergency caesarean section which could lead to implementation of preventative strategies. *[Corrections added on 29 January 2018, after first online publication, '(OR for the 4th quartile (>7th centile)' has been changed to '(OR for the 4th quartile (>75th centile)'.].

Risk of operative delivery for intrapartum fetal compromise in small-for-gestational-age fetuses at term: an internally validated prediction model

BACKGROUND

Small-for-gestational-age fetuses are at an increased risk of intrapartum fetal compromise requiring operative delivery. Factors associated with the risk of intrapartum fetal compromise are yet to be established, and a comprehensive model accounting for both the antenatal and intrapartum variables is lacking.

OBJECTIVE

We aimed to develop and validate a predictive model for the risk of operative delivery for presumed intrapartum fetal compromise in fetuses suspected to be small for gestational age at term.

STUDY DESIGN

This was a single-center cohort study of small-for-gestational-age fetuses, defined as estimated fetal weight below the 10th centile in singleton pregnancies at term. The variables included known risk factors for operative delivery because of fetal compromise: maternal characteristics, estimated fetal weight, abdominal circumference, Doppler parameters, gestational age at delivery, induction of labor, and intrapartum risk factors (presence of meconium, augmentation of labor using oxytocin, the use of epidural analgesia, intrapartum pyrexia, and hemorrhage). The receiver-operating characteristics curve analysis was used to investigate the predictive accuracy. Internal validation of the models was performed with bootstrapped data sets.

RESULTS

A total of 927 term pregnancies with 18.7% operative deliveries were included. The antenatal model (area under the curve, 0.69; 95% confidence interval, 0.65-0.73) using only the antenatal risk factors included parity, abdominal circumference centile, gestational age at delivery beyond 39 weeks' gestation, and the cerebroplacental ratio multiples of median. The combined model (area under the curve, 0.76; 95% confidence interval, 0.72-0.80), using both the antenatal and intrapartum risk factors, included the gestational age at delivery beyond 39 weeks' gestation (odds ratio, 1.62; 95% confidence interval, 1.14-2.56), the cerebroplacental ratio multiples of median (odds ratio, 0.38; 95% confidence interval, 0.18-0.79), parity (odds ratio 0.35; 95% confidence interval, 0.22-0.54), induction of labor (odds ratio 1.63; 95% confidence interval, 1.11-2.40), augmentation using oxytocin (odds ratio, 1.84; 95% confidence interval, 1.23-2.73) and the use of epidural analgesia (odds ratio, 2.80; 95% confidence interval, 1.94-4.04). The results indicate that the model has good discrimination and, according to the Hosmer-Lemeshow test, has good fit (P = .591).

CONCLUSION

The prediction model demonstrates 6 important risk factors that are associated with the risk of operative delivery for fetal compromise in small-for-gestational-age fetuses at term. The model shows good discrimination and fit and has the potential to be used for clinical decision making and to counsel women about their individual intrapartum risk.

Reduced growth velocity across the third trimester is associated with placental insufficiency in fetuses born at a normal birthweight: a prospective cohort study

BACKGROUND

While being small-for-gestational-age due to placental insufficiency is a major risk factor for stillbirth, 50% of stillbirths occur in appropriate-for-gestational-age (AGA, > 10th centile) fetuses. AGA fetuses are plausibly also at risk of stillbirth if placental insufficiency is present. Such fetuses may be expected to demonstrate declining growth trajectory across pregnancy, although they do not fall below the 10th centile before birth. We investigated whether reduced growth velocity in AGA fetuses is associated with antenatal, intrapartum and neonatal indicators of placental insufficiency.

METHODS

We performed a prospective cohort study of 308 nulliparous women who subsequently gave birth to AGA infants. Ultrasound was utilised at 28 and 36 weeks' gestation to determine estimated fetal weight (EFW) and abdominal circumference (AC). We correlated relative EFW and AC growth velocities with three clinical indicators of placental insufficiency, namely (1) fetal cerebroplacental ratio (CPR; CPR < 5th centile reflects placental resistance, and blood flow redistribution to the brain - a fetal response to hypoxia); (2) neonatal acidosis after the hypoxic challenge of labour (umbilical artery (UA) pH < 7.15 at birth); and (3) low neonatal body fat percentage (BF%, measured by air displacement plethysmography) reflecting reduced nutritional reserve in utero.

RESULTS

For each one centile reduction in EFW growth velocity between 28 and 36 weeks' gestation, there was a 2.4% increase in the odds of cerebral redistribution (CPR < 5th centile, odds ratio (OR) (95% confidence interval) = 1.024 (1.005-1.042), P = 0.012) and neonatal acidosis (UA pH < 7.15, OR = 1.024 (1.003-1.046), P = 0.023), and a 3.3% increase in the odds of low BF% (OR = 1.033 (1.001-1.067), P = 0.047). A decline in EFW of > 30 centiles between 28 and 36 weeks (compared to greater relative growth) was associated with cerebral redistribution (CPR < 5th centile relative risk (RR) = 2.80 (1.25-6.25), P = 0.026), and a decline of > 35 centiles was associated with neonatal acidosis (UA pH < 7.15 RR = 3.51 (1.40-8.77), P = 0.030). Similar associations were identified between low AC growth velocity and clinical indicators of placental insufficiency.

CONCLUSIONS

Reduced growth velocity between 28 and 36 weeks' gestation among fetuses born AGA is associated with antenatal, intrapartum and neonatal indicators of placental insufficiency. These fetuses potentially represent an important unrecognised cohort at increased risk of stillbirth and may warrant more intensive antenatal surveillance.

Possible relationship between general and pregnancy-related anxiety during the first half of pregnancy and the birth process: a prospective cohort study

OBJECTIVES

The rate of interventions during childbirth has increased dramatically during the last decades. Maternal anxiety might play a role in the progress of the labour process and interventions during labour. This study aimed to identify associations between anxiety in the first half of pregnancy and the birth process, including any interventions required during labour. In addition, differences in the associations by parity and ethnicity were explored.

DESIGN

Prospective cohort study.

SETTING

Primary care midwifery practices and secondary/tertiary care obstetric practices in Amsterdam, participating in the multiethnic ABCD (Amsterdam Born Children and their Development) study (participation rate 96%; response 8266/12 373 (67%)).

PARTICIPANTS

Included were women with singletons, alive at labour start, with a gestational age ≥24 weeks (n=6443).

INDEPENDENT VARIABLE

General anxiety (State-Trait Anxiety Inventory state) and pregnancy-related anxiety (Pregnancy-Related Anxieties Questionnaire (PRAQ)) were self-reported in the first half of pregnancy.

OUTCOMES

Associations between both forms of anxiety and several indicators of the birth process were analysed. Subgroup analyses were performed for parity and ethnicity.

RESULTS

The prevalence of high general anxiety (State-Trait Anxiety Inventory score ≥43) and pregnancy-related anxiety (PRAQ score ≥P90) were 30.9% and 11.0%, respectively. After adjustment, in nulliparae, both general anxiety and pregnancy-related anxiety were associated with pain relief and/or sedation (OR for general anxiety 1.23; 95% CI 1.02 to 1.48; OR for pregnancy-related anxiety 1.45; 95% CI 1.14 to 1.85). In multiparae, general anxiety was associated with induction of labour (OR 1.53; 95% CI 1.16 to 2.03) and pregnancy-related anxiety was associated with primary caesarean section (OR 1.66; 95% CI 1.02 to 2.70). Associations were largely similar for all ethnicities.

CONCLUSIONS

High levels of general and pregnancy-related anxiety in early pregnancy contribute modestly to more interventions during the birth process with similar associations between ethnic groups, but with some differences between nulliparae and multiparae.

Association between Maternal Serum Concentrations of Angiopoietin-like Protein 2 in Early Pregnancy and Subsequent Risk of Gestational Diabetes Mellitus

Background:

A recent study reported a positive association between elevated serum levels of angiopoietin-like protein 2 (ANGPTL2) and the development of type 2 diabetes in a general population. However, the relationship of serum ANGPTL2 levels with the risk of developing gestational diabetes mellitus (GDM) has not been reported to date. The aim of this study was to investigate the change of maternal serum ANGPTL2 concentrations in the first trimester of pregnancy and to determine whether ANGPTL2 is a biomarker for subsequent GDM development.

Methods:

We conducted a prospective, nested case-control study in a pregnancy cohort. First-trimester ANGPTL2 levels were measured using a high-resolution assay in 89 women who subsequently developed GDM and in a random sample of 177 women who remained euglycemic throughout the pregnancy. Median ANGPTL2 levels were compared using Mann-Whitney U-test. Logistic regression was used to compute unadjusted and multivariable-adjusted odds ratios for developing GDM among ANGPTL2 quartiles.

Results:

The serum levels of ANGPTL2 was higher in women with GDM than that in women without GDM (3.06 [2.59, 3.65] ng/ml vs. 2.46 [2.05, 2.96] ng/ml, P = 0.003). Fasting blood glucose was higher in women with GDM than that in women without GDM (5.0 ± 0.9 mmol/L vs. 4.4 ± 0.6 mmol/L, P < 0.001). Glucose challenge test showed that the blood glucose was higher in women with GDM than that in women without GDM (9.1 ± 3.5 mmol/L vs. 6.2 ± 1.2 mmol/L, P < 0.001). A multivariate model adjusted for baseline characteristics, medical complications, and gestational characteristics revealed that the risk of developing GDM among women in Q4 compared with Q1 was 2.90-fold more likely to develop GDM later in pregnancy.

Conclusions:

At 11–13 weeks in pregnancies that develop GDM, the serum concentration of ANGPTL2 is increased, and it can be combined with maternal factors to provide effective early screening for GDM.

A generic nomogram for multinomial prediction models: theory and guidance for construction

BACKGROUND

The use of multinomial logistic regression models is advocated for modeling the associations of covariates with three or more mutually exclusive outcome categories. As compared to a binary logistic regression analysis, the simultaneous modeling of multiple outcome categories using a multinomial model often better resembles the clinical setting, where a physician typically must distinguish between more than two possible diagnoses or outcome events for an individual patient (e.g., the differential diagnosis). A disadvantage of the multinomial logistic model is that the interpretation of its results is often complex. In particular, the calculation of predicted probabilities for the various outcomes requires a series of careful calculations. Nomograms are widely used in studies reporting binary logistic regression models to facilitate the interpretation of the results and allow the calculation of the predicted probability for individuals.

METHODS AND RESULTS

In this paper we outline an approach for deriving a generic nomogram for multinomial logistic regression models and an accompanying scoring chart that can further simplify the calculation of predicted multinomial probabilities. We illustrate the use of the nomogram and scoring chart and their interpretation using a clinical example.

CONCLUSIONS

The generic multinomial nomogram and scoring chart can be used irrespective of the number of outcome categories that are present.

Cesarean delivery among women with prolonged labor induction

OBJECTIVE

The objective of this study was to determine characteristics associated with cesarean delivery among women with labor induction lasting over 24 h.

STUDY DESIGN

Women with live singleton pregnancies without prior cesarean delivery undergoing a labor induction lasting >24 h between September 2006 and March 2009 at Duke University Hospital were identified. Collected variables were compared between subjects by mode of delivery. A multivariate logistic regression model for the outcome cesarean delivery was constructed separately for nulliparous and parous women.

RESULTS

There were 303 women who met inclusion criteria. The overall cesarean delivery rate was 57% (n=172) and remained constant with time (P=0.15, test-for-trend). Nulliparous women having a cesarean delivery were more likely to be obese [adjusted OR (aOR) 2.00; 95% CI 1.05, 3.80] and have a larger fetus [aOR 1.11 (aOR for every 100 g increase in birthweight), 95% CI 1.03, 1.20] compared to those having a vaginal delivery.

CONCLUSION

Increasing BMI and birthweight were independent predictors of cesarean delivery among nulliparous women with prolonged labor induction. Despite this, after 24 h of labor induction, the overall mean cesarean delivery rate remained constant at 57%, and did not change with time. Among women having a vaginal delivery following a prolonged labor induction, we saw high rates of shoulder dystocia, operative vaginal delivery and severe perineal laceration.

Placental Insufficiency in Fetuses That Slow in Growth but Are Born Appropriate for Gestational Age: A Prospective Longitudinal Study

OBJECTIVES

To determine whether fetuses that slow in growth but are then born appropriate for gestational age (AGA, birthweight >10th centile) demonstrate ultrasound and clinical evidence of placental insufficiency.

METHODS

Prospective longitudinal study of 48 pregnancies reaching term and a birthweight >10th centile. We estimated fetal weight by ultrasound at 28 and 36 weeks, and recorded birthweight to determine the relative change in customised weight across two timepoints: 28-36 weeks and 28 weeks-birth. The relative change in weight centiles were correlated with fetoplacental Doppler findings performed at 36 weeks. We also examined whether a decline in growth trajectory in fetuses born AGA was associated with operative deliveries performed for suspected intrapartum compromise.

RESULTS

The middle cerebral artery pulsatility index (MCA-PI) showed a linear association with fetal growth trajectory. Lower MCA-PI readings (reflecting greater diversion of blood supply to the brain) were significantly associated with a decline in fetal growth, both between 28-36 weeks (p = 0.02), and 28 weeks-birth (p = 0.0002). The MCA-PI at 36 weeks was significantly higher among those with a relative weight centile fall <20%, compared to those with a moderate centile fall of 20-30% (mean MCA-PI 1.94 vs 1.61; p<0.05), or severe centile fall of >30% (mean MCA-PI 1.94 vs 1.56; p<0.01). Of 43 who labored, operative delivery for suspected intrapartum fetal compromise was required in 12 cases; 9/18 (50%) cases where growth slowed, and 3/25 (12%) where growth trajectory was maintained (p = 0.01).

CONCLUSIONS

Slowing in growth across the third trimester among fetuses subsequently born AGA was associated with ultrasound and clinical features of placental insufficiency. Such fetuses may represent an under-recognised cohort at increased risk of stillbirth.

Prognostic models in obstetrics: available, but far from applicable

Health care provision is increasingly focused on the prediction of patients' individual risk for developing a particular health outcome in planning further tests and treatments. There has been a steady increase in the development and publication of prognostic models for various maternal and fetal outcomes in obstetrics. We undertook a systematic review to give an overview of the current status of available prognostic models in obstetrics in the context of their potential advantages and the process of developing and validating models. Important aspects to consider when assessing a prognostic model are discussed and recommendations on how to proceed on this within the obstetric domain are given. We searched MEDLINE (up to July 2012) for articles developing prognostic models in obstetrics. We identified 177 papers that reported the development of 263 prognostic models for 40 different outcomes. The most frequently predicted outcomes were preeclampsia (n = 69), preterm delivery (n = 63), mode of delivery (n = 22), gestational hypertension (n = 11), and small-for-gestational-age infants (n = 10). The performance of newer models was generally not better than that of older models predicting the same outcome. The most important measures of predictive accuracy (ie, a model's discrimination and calibration) were often (82.9%, 218/263) not both assessed. Very few developed models were validated in data other than the development data (8.7%, 23/263). Only two-thirds of the papers (62.4%, 164/263) presented the model such that validation in other populations was possible, and the clinical applicability was discussed in only 11.0% (29/263). The impact of developed models on clinical practice was unknown. We identified a large number of prognostic models in obstetrics, but there is relatively little evidence about their performance, impact, and usefulness in clinical practice so that at this point, clinical implementation cannot be recommended. New efforts should be directed toward evaluating the performance and impact of the existing models.

A Scoring Tool to Identify East African HIV-1 Serodiscordant Partnerships with a High Likelihood of Pregnancy

Introduction

HIV-1 prevention programs targeting HIV-1 serodiscordant couples need to identify couples that are likely to become pregnant to facilitate discussions about methods to minimize HIV-1 risk during pregnancy attempts (i.e. safer conception) or effective contraception when pregnancy is unintended. A clinical prediction tool could be used to identify HIV-1 serodiscordant couples with a high likelihood of pregnancy within one year.

Methods

Using standardized clinical prediction methods, we developed and validated a tool to identify heterosexual East African HIV-1 serodiscordant couples with an increased likelihood of becoming pregnant in the next year. Datasets were from three prospectively followed cohorts, including nearly 7,000 couples from Kenya and Uganda participating in HIV-1 prevention trials and delivery projects.

Results

The final score encompassed the age of the woman, woman’s number of children living, partnership duration, having had condomless sex in the past month, and non-use of an effective contraceptive. The area under the curve (AUC) for the probability of the score to correctly predict pregnancy was 0.74 (95% CI 0.72–0.76). Scores ≥7 predicted a pregnancy incidence of >17% per year and captured 78% of the pregnancies. Internal and external validation confirmed the predictive ability of the score.

Discussion

A pregnancy likelihood score encompassing basic demographic, clinical and behavioral factors defined African HIV-1 serodiscordant couples with high one-year pregnancy incidence rates. This tool could be used to engage African HIV-1 serodiscordant couples in counseling discussions about fertility intentions in order to offer services for safer conception or contraception that align with their reproductive goals.

Risk indicators for referral during labor from community midwife to gynecologist: a prospective cohort study

OBJECTIVE

To identify risk indicators for referral during labor from community midwife to a gynecologist in a prospective cohort of women with a singleton term pregnancy, starting labor with a community midwife between 2000 and 2007, registered in the Dutch national perinatal registry.

MAIN OUTCOME MEASURES

Referral from community midwife to a gynecologist during labor, because of fetal distress, failure to progress in second stage of labor, meconium stained amniotic fluid, failure to progress in first stage of labor, wish for pain relief, a combination of other less urgent reasons or no referral (reference).

RESULTS

A total of 241 595 (32%) were referred from community midwife to a gynecologist during labor, because of fetal distress (FD;5%), failure to progress in second stage of labor (FTP2;14%), meconium stained amniotic fluid (MSAF;24%), failure to progress in first stage of labor (FTP1;17%), wish for pain relief (WFPR;7%) or a combination of other less urgent reasons, for example, malpresentation (e.g. breech) or other nonspecified problems (OTHER;33%). The strongest overall risk indicators were gestational age (lower risk of referral because of FD, FTP2, MSAF, FTP1 and WFPR and a higher risk of referral because of OTHER at a gestational age between 37(+0) and 37(+)(6) weeks, and higher risks of referral for all reasons at a gestational age ≥41(+)(0) when compared to a gestational age between 38 (+)(0) and 40 (+)(6) weeks and no referral), the intended place of delivery (higher risk of all types of referral compared to no referral when the intended place of delivery was either at a midwife-led birth center or a hospital instead of at home) and birth history (higher risk of all types of referral compared to no referral when women had a history of instrumental vaginal delivery or when they were nulliparous instead of being multiparous without a history of an instrument vaginal delivery). Risk indicators associated with specific reasons of referral were maternal age, ethnicity, degree of urbanization, social economic status, neonatal gender and birth weight.

CONCLUSIONS

Among low-risk pregnant women, a referral during labor is associated with readily available risk indicators. These risk indicators may be used to increase referral risk awareness and to counsel women for the intended place to start labor.

Predicting Cesarean Delivery After Induction of Labor Among Nulliparous Women at Term

OBJECTIVE

To identify independent risk factors for cesarean delivery after induction of labor and to develop a nomogram for predicting cesarean delivery among nulliparous women undergoing induction of labor at term.

METHODS

This is a retrospective cohort study including nulliparous women with singleton, term (37 0/7 weeks of gestation or greater), cephalic pregnancies undergoing induction of labor from July 1, 2006, through May 31, 2012, at a tertiary care academic center. Inductions were identified using International Classification of Diseases, 9th Revision codes. Demographic, delivery, and outcome data were abstracted manually from the medical record. Women with a contraindication to vaginal delivery (malpresentation, abnormal placentation, prior myomectomy) were excluded. Independent risk factors for cesarean delivery were identified using logistic regression.

RESULTS

During the study period, there were 785 nulliparous inductions that met study criteria; 231 (29.4%) underwent cesarean delivery. Independent risk factors associated with an increased risk of cesarean delivery included older maternal age, shorter maternal height, greater body mass index, greater weight gain during pregnancy, older gestational age, hypertension, diabetes mellitus, and initial cervical dilation less than 3 cm. A nomogram was constructed based on the final model with a bias-corrected c-index of 0.709 (95% confidence interval 0.671-0.750).

CONCLUSION

We identified independent risk factors that can be used to predict cesarean delivery among nulliparous women undergoing induction of labor at term. If validated in other populations, the nomogram could be useful for individualized counseling of women with a combination of identifiable antepartum risk factors.

LEVEL OF EVIDENCE

II.

Increased maternal TSH and decreased maternal FT4 are associated with a higher operative delivery rate in low-risk pregnancies: A prospective cohort study

Background

The increasing number of operative deliveries is a topic of major concern in modern obstetrics. Maternal thyroid function is of known influence on many obstetric parameters. Our objective was to investigate a possible relation between maternal thyroid function, and operative deliveries. Secondary aim was to explore whether thyroid function was related to specific reasons for operative deliveries.

Methods

In this prospective cohort study, low-risk Caucasian women, pregnant of a single cephalic fetus were included. Women with known auto-immune disease, a pre-labour Caesarean section, induction of labour, breech presentation or preterm delivery were excluded. In all trimesters of pregnancy the thyroid function was assessed. Differences in mean TSH and FT4 were assessed using t-test. Mean TSH and FT4 levels for operative deliveries were determined by one way ANOVA. Repeated measurement analyses were performed (ANOVA), adjusting for BMI, partiy, maternal age and gestational age at delivery.

Results

In total 872 women were included, of which 699 (80.2 %) had a spontaneous delivery. At 36 weeks gestation women who had an operative delivery had a significantly higher mean TSH (1.63mIU/L versus 1.46mIU/L, p = 0.025) and lower mean FT4 (12.9pmol/L versus 13.3pmol/L, p = 0.007)) compared to women who had a spontaneous delivery. Mean TSH was significantly higher (p = 0.026) and mean FT4 significantly lower (p = 0.030) throughout pregnancy for women with an operative delivery due to failure to progress in second stage of labour, compared to women with a spontaneous delivery or operative delivery for other reasons.

Conclusions

Increased TSH and decreased FT4 seem to be associated with more operative vaginal deliveries and Caesarean sections. After adjusting for several confounders the association remained for operative deliveries due to failure to progress in second stage of labour, possibly to be explained by less efficient uterine action.

Is fetal cerebroplacental ratio an independent predictor of intrapartum fetal compromise and neonatal unit admission?

OBJECTIVE

We sought to evaluate the association between fetal cerebroplacental ratio (CPR) and intrapartum fetal compromise and admission to the neonatal unit (NNU) in term pregnancies.

STUDY DESIGN

This was a retrospective cohort study in a single tertiary referral center over a 14-year period from 2000 through 2013. The umbilical artery pulsatility index, middle cerebral artery pulsatility index, and CPR were recorded within 2 weeks of delivery. The birthweight (BW) values were converted into centiles and Doppler parameters converted into multiples of median (MoM), adjusting for gestational age using reference ranges. Logistic regression analysis was performed to identify, and adjust for, potential confounders.

RESULTS

The study cohort included 9772 singleton pregnancies. The rates of operative delivery for presumed fetal compromise and neonatal admission were 17.2% and 3.9%, respectively. Doppler CPR MoM was significantly lower in pregnancies requiring operative delivery or admission to NNU for presumed fetal compromise (P < .01). On multivariate logistic regression, both CPR MoM and BW centile were independently associated with the risk of operative delivery for presumed fetal compromise (adjusted odds ratio [OR], 0.67; 95% confidence interval [CI], 0.52-0.87; P = .003 and adjusted OR, 0.994; 95% CI, 0.992-0.997; P < .001, respectively). The latter associations persisted even after exclusion of small-for-gestational-age cases from the cohort. Multivariate logistic regression also demonstrated that CPR MoM was an independent predictor for NNU admission at term (adjusted OR, 0.55; 95% CI, 0.33-0.92; P = .021), while BW centile was not (adjusted OR, 1.00; 95% CI, 0.99-1.00; P = .794). The rates of operative delivery for presumed fetal compromise were significantly higher for appropriate-for-gestational-age fetuses with low CPR MoM (22.3%) compared to small-for-gestational-age fetuses with normal CPR MoM (17.3%).

CONCLUSION

Lower fetal CPR, regardless of the fetal size, was independently associated with the need for operative delivery for presumed fetal compromise and with NNU admission at term. The extent to which fetal hemodynamic status could be used to predict perinatal morbidity and optimize the mode of delivery merits further investigation.

Antenatal depressive symptoms and the risk of preeclampsia or operative deliveries: a meta-analysis

BACKGROUND

The purpose of the study was to investigate the association between depression and/or depressive symptoms during pregnancy and the risk of an operative delivery or preeclampsia, and to quantify the strength of the association.

METHODS

A search of the PubMed, SCI/SSCI, Proquest PsycARTICLES and CINAHL databases was supplemented by manual searches of bibliographies of key retrieved articles and review articles. We aimed to include case control or cohort studies that reported data on antenatal depression and /or depressive symptoms and the risk of an operative delivery and/or preeclampsia.

RESULTS

Twelve studies with self-reported screening instruments were eligible for inclusion with a total of 8400 participants. Seven articles that contained 4421 total participants reported the risk for an operative delivery, and five articles that contained 3979 total participants reported the risk for preeclampsia. The pooled analyses showed that both operative delivery and preeclampsia had a statistically significant association with antenatal depressive symptoms (RR = 1.24; 95% CI, 1.14 to 1.35, and OR = 1.63, 95% CI, 1.32 to 2.02, respectively). When the pre-pregnancy body mass indices were controlled in their initial design, the risk for preeclampsia still existed (OR = 1.48, 95% CI, 1.04 to 2.01), while the risk for an operative delivery became uncertain (RR = 1.01, 95% CI, 0.85 to 1.22).

CONCLUSIONS

Antenatal depressive symptoms are associated with a moderately increased risk of an operative delivery and preeclampsia. An abnormal pre-pregnancy body mass index may modify this association.

Association between levator hiatal dimensions on ultrasound during first pregnancy and mode of delivery

OBJECTIVES

To determine the association between levator hiatal dimensions, measured using transperineal ultrasound, in women during their first pregnancy and the subsequent mode of delivery, stratified by the indication for intervention.

METHODS

In this prospective observational study, 280 nulliparous women with a singleton pregnancy were invited for transperineal ultrasound examination at 12 and 36 weeks' gestation. Their levator hiatal dimensions were measured at rest, on pelvic floor muscle contraction and on Valsalva maneuver. The subsequent mode of delivery was classified into five categories: spontaneous vaginal delivery, instrumental vaginal delivery owing to fetal distress, instrumental vaginal delivery owing to failure to progress, Cesarean section owing to fetal distress and Cesarean section owing to failure to progress. Levator hiatal dimensions according to mode of delivery were compared by analysis of variance and Tukey's post-hoc test. Since multiple comparison tests were performed, the statistical significance level was corrected using the Bonferroni method.

RESULTS

Of the 252 women included, those who delivered by Cesarean section because of failure to progress had a significantly smaller levator hiatal transverse diameter on pelvic floor contraction at 12 weeks' gestation than did women who had a spontaneous vaginal delivery (Tukey's post-hoc test, P < 0.001). There was also a trend towards a smaller hiatal area on pelvic floor contraction at 12 weeks' gestation in women who delivered by Cesarean section because of failure to progress compared to women who had a spontaneous vaginal delivery (Tukey's post-hoc test, P = 0.005). In women who had an instrumental vaginal delivery because of failure to progress there was a trend towards a smaller levator hiatal anteroposterior diameter on pelvic floor contraction at 36 weeks' gestation compared with women who had a spontaneous vaginal delivery (Tukey's post-hoc test, P = 0.033).

CONCLUSIONS

Smaller levator hiatal dimensions on pelvic floor contraction during first pregnancy are associated with a subsequent instrumental vaginal delivery or a Cesarean section owing to failure to progress.