The behavior of the uterine cervix during labor

Little appears to be kno'\vn about the relationship between behavior of the uterine cervix and myometrial activity during the first stage of labor.ns Considering the extensive medical and social problems related to dysfunctional behavior of the cervix during parturition, the lack of knowledge of cervical physiology and pathophysiology during labor is surprising. Labor dystocia, i.e. the failure of the cervix to dilate despite adequate uterine contractions, is the single factor that has contributed most to the increase in cesarean deliveries. On the other hand. preterm delivery is the most significant contributor to perinatal morbidity and mortality in the Western world. A better understanding of the physiology of cervical dilatation in relation to uterine contractions might contribute to the solution of these obstetric dilemmas. In order to improve the knowledge of the physiologic changes of the cervix during parturition. a reliable technique for monitoring cervical behavior during labor is indispensable. Until recently digital examination of the cervical os by the attending obstetrician \vas the only method available to assess the condition of the cervix during parturition. Using digital palpation of the cervix. Friedman demonstrated that the curve of cervical dilatation plotted against time is sigmoid-shaped. Although useful in everyday clinical practice. digital examination has major shortcomings. The inter-observer variability is considerable and the intermittent nature of the procedure does not allow an assessment of the dynamics of the cervix during labor. Despite these disadvantages, the knowledge of cervical changes during labor depends almost exclusively on data obtained by digital examination. For research purposes ultrasound cen·imetry seems to be the method of choice for measurement of cervical dilatation during labor. The ultrasound cervimeter uses two miniaturized transducers that are attached to the cervix to measure cervical dilatation during the first stage of labor. The method offers continuous recording of cervical dilatation during labor and can easily be combined with measurement of intrauterine pressure. thus allo\ving the assessment of cervical dynamics during labor. Interesting and promising results have been published in a preliminary report. For the first time. cervical dilatation patterns ·were objectively established. However insufficient clinical data are available to assess the potentials of ultrasound cervimetry and a thorough evaluation of its value is imperative. A second handicap for the study of cervical behavior during labor is the lack of insight into the mechanisms of control of cervical dilatation.18 Several observations suggest that prostaglandins are involved in the achievement of successful effacement and dilatation of the cervix. once cervical ripening is established. Prostaglandins have been shown to be important regulators of the physiology of the cervix during pregnancy, in particular during the last trimester. Concentrations of prostaglandin E2 en F2a rise markedly at the onset of labor and the accumulation of prostaglandins is less in labor progressing slowly than in labor of normal duration. However. thorough studies of prostaglandin-mediated cervical changes during. labor are lacking

A clinical prediction model to assess the risk of operative delivery

Objective To predict instrumental vaginal delivery or caesarean section for suspected fetal distress or failure to progress. Design Secondary analysis of a randomised trial. Setting Three academic and six non-academic teaching hospitals in the Netherlands. Population 5667 labouring women with a singleton term pregnancy in cephalic presentation. Methods We developed multinomial prediction models to assess the risk of operative delivery using both antepartum (model 1) and antepartum plus intrapartum characteristics (model 2). The models were validated by bootstrapping techniques and adjusted for overfitting. Predictive performance was assessed by calibration and discrimination (area under the receiver operating characteristic), and easy-to-use nomograms were developed. Main outcome measures Incidence of instrumental vaginal delivery or caesarean section for fetal distress or failure to progress with respect to a spontaneous vaginal delivery (reference). Results 375 (6.6%) and 212 (3.6%) women had an instrumental vaginal delivery or caesarean section due to fetal distress, and 433 (7.6%) and 571 (10.1%) due to failure to progress, respectively. Predictors were age, parity, previous caesarean section, diabetes, gestational age, gender, estimated birthweight (model 1) and induction of labour, oxytocin augmentation, intrapartum fever, prolonged rupture of membranes, meconium stained amniotic fluid, epidural anaesthesia, and use of ST-analysis (model 2). Both models showed excellent calibration and the receiver operating characteristics areas were 0.70–0.78 and 0.73–0.81, respectively. Conclusion In Dutch women with a singleton term pregnancy in cephalic presentation, antepartum and intrapartum characteristics can assist in the prediction of the need for an instrumental vaginal delivery or caesarean section for fetal distress or failure to progress

Pregnancy is predictable: A large-scale prospective external validation of the prediction of spontaneous pregnancy in subfertile couples

Background: Prediction models for spontaneous pregnancy may be useful tools to select subfertile couples that have good fertility prospects and should therefore be counselled for expectant management. We assessed the accuracy of a recently published prediction model for spontaneous pregnancy in a large prospective validation study. Methods: In 38 centres, we studied a consecutive cohort of subfertile couples, referred for an infertility work-up. Patients had a regular menstrual cycle, patent tubes and a total motile sperm count (TMC) >3 × 106. After the infertility work-up had been completed, we used a prediction model to calculate the chance of a spontaneous ongoing pregnancy (www.freya.nl/probability.php). The primary end-point was time until the occurrence of a spontaneous ongoing pregnancy within 1 year. The performance of the pregnancy prediction model was assessed with calibration, which is the comparison of predicted and observed ongoing pregnancy rates for groups of patients and discrimination. Results: We included 3021 couples of whom 543 (18%) had a spontaneous ongoing pregnancy, 57 (2%) a non-successful pregnancy, 1316 (44%) started treatment, 825 (27%) neither started treatment nor became pregnant and 280 (9%) were lost to follow-up. Calibration of the prediction model was almost perfect. In the 977 couples (32%) with a calculated probability between 30 and 40%, the observed cumulative pregnancy rate at 12 months was 30%, and in 611 couples (20%) with a probability of ≥40%, this was 46%. The discriminative capacity was similar to the one in which the model was developed (c-statistic 0.59). Conclusions: As the chance of a spontaneous ongoing pregnancy among subfertile couples can be accurately calculated, this prediction model can be used as an essential tool for clinical decision-making and in counselling patients. The use of the prediction model may help to prevent unnecessary treatment

Identification of cases with adverse neonatal outcome monitored by cardiotocography versus ST analysis: secondary analysis of a randomized trial

OBJECTIVE: To evaluate whether correct adherence to clinical guidelines might have led to prevention of cases with adverse neonatal outcome. DESIGN: Secondary analysis of cases with adverse outcome in a multicenter randomized clinical trial. SETTING: Nine Dutch hospitals. POPULATION: Pregnant women with a term singleton fetus in cephalic position. METHODS: Data were obtained from a randomized trial that compared monitoring by STAN® (index group) with cardiotocography (control group). In both trial arms, three observers independently assessed the fetal surveillance results in all cases with adverse neonatal outcome, to determine whether an indication for intervention was present, based on current clinical guidelines. MAIN OUTCOME MEASURES: Adverse neonatal outcome cases fulfilled one or more of the following criteria: (i) metabolic acidosis in umbilical cord artery (pH 12 mmol/L); (ii) umbilical cord artery pH < 7.00; (iii) perinatal death; and/or (iv) signs of moderate or severe hypoxic ischemic encephalopathy. RESULTS: We studied 5681 women, of whom 61 (1.1%) had an adverse outcome (26 index; 35 control). In these women, the number of performed operative deliveries for fetal distress was 18 (69.2%) and 16 (45.7%), respectively. Reassessment of all 61 cases showed that there was a fetal indication to intervene in 23 (88.5%) and 19 (57.6%) cases, respectively. In 13 (50.0%) vs. 11 (33.3%) cases, respectively, this indication occurred more than 20 min before the time of delivery, meaning that these adverse outcomes could possibly have been prevented. CONCLUSIONS: In our trial, more strict adherence to clinical guidelines could have led to additional identification and prevention of adverse outcome.Michelle E.M.H. Westerhuis ... Ben Willem J. Mol ... et al

Cost-effectiveness of cardiotocography plus ST analysis of the fetal electrocardiogram compared with cardiotocography only

OBJECTIVE. To assess the cost-effectiveness of addition of ST analysis of the fetal electrocardiogram (ECG; STAN®) to cardiotocography (CTG) for fetal surveillance during labor compared with CTG only. DESIGN. Cost-effectiveness analysis based on a randomized clinical trial on ST analysis of the fetal ECG. SETTING. Obstetric departments of three academic and six general hospitals in The Netherlands. POPULATION. Laboring women with a singleton high-risk pregnancy, a fetus in cephalic presentation, a gestational age > 36 weeks and an indication for internal electronic fetal monitoring. METHODS. A trial-based cost-effectiveness analysis was performed froma health-care provider perspective. MAIN OUTCOME MEASURES. Primary health outcome was the incidence of metabolic acidosis measured in the umbilical artery. Direct medical costswere estimated fromstart of labor to childbirth. Cost-effectiveness was expressed as costs to prevent one case of metabolic acidosis. RESULTS. The incidence of metabolic acidosis was 0.7% in the ST-analysis group and 1.0% in the CTG-only group (relative risk 0.70; 95% confidence interval 0.38–1.28). Per delivery, the mean costs per patient of CTG plus ST analysis (n = 2 827) were €1 345 vs. €1 316 for CTG only (n=2 840), with a mean difference of €29 (95% confidence interval −€9 to €77) until childbirth. The incremental costs of ST analysis to prevent one case of metabolic acidosis were €9 667. CONCLUSIONS. The additional costs of monitoring by ST analysis of the fetal ECG are very limited when compared with monitoring by CTG only and very low compared with the total costs of delivery.Sylvia M.C. Vijgen ... Ben Willem J. Mol ... et al

Prediction of neonatal metaboic acidos in women with a singleton term pregnancy in cephalic presentation

We sought to predict neonatal metabolic acidosis at birth using antepartum obstetric characteristics (model 1) and additional characteristics available during labor (model 2). In 5667 laboring women from a multicenter randomized trial that had a high-risk singleton pregnancy in cephalic presentation beyond 36 weeks of gestation, we predicted neonatal metabolic acidosis. Based on literature and clinical reasoning, we selected both antepartum characteristics and characteristics that became available during labor. After univariable analyses, the predictors of the multivariable models were identified by backward stepwise selection in a logistic regression analysis. Model performance was assessed by discrimination and calibration. To correct for potential overfitting, we (internally) validated the models with bootstrapping techniques. Of 5667 neonates born alive, 107 (1.9%) had metabolic acidosis. Antepartum predictors of metabolic acidosis were gestational age, nulliparity, previous cesarean delivery, and maternal diabetes. Additional intrapartum predictors were spontaneous onset of labor and meconium-stained amniotic fluid. Calibration and discrimination were acceptable for both models (c-statistic 0.64 and 0.66, respectively). In women with a high-risk singleton term pregnancy in cephalic presentation, we identified antepartum and intrapartum factors that predict neonatal metabolic acidosis at birth

Prediction of Neonatal Metabolic Acidosis in Women with a Singleton Term Pregnancy in Cephalic Presentation

Research into fetal development and medicin