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Objective: To estimate whether a high lactate concentration in amniotic fluid, together with cardiotocography, can be used as an indicator for an increased risk of adverse neonatal outcome at delivery., Method: A prospective cohort study was performed at two tertiary center labor wards in Sweden. Healthy women with full-term, singleton pregnancies and cephalic presentation in spontaneous active labor were included in the study (N=825). Lactate concentration in samples of amniotic fluid collected in the course of vaginal examinations during labor were correlated with cardiotocography 30 minutes before delivery and a composite score for adverse neonatal outcome., Results: High lactate concentration in amniotic fluid (greater than 10.1 mmol/L) was associated with an adverse neonatal outcome (odds ratio [OR] 4.4, 95% confidence interval [CI] 2.3-8.2). Fetal bradycardia within 30 minutes before delivery was also associated with an increased risk of adverse neonatal outcome (OR 7.4, 95% CI 3.04-18.11). If lactate in amniotic fluid was greater than 10.1 mmol/L and bradycardia was seen together, the risk of delivering a neonate with an adverse neonatal outcome was increased 11-fold (OR 10.7, 95% CI 3.7-31.7)., Conclusion: High lactate concentration in amniotic fluid and fetal bradycardia during the last 30 minutes before delivery indicate an increased risk of adverse neonatal outcome at delivery.

It is generally believed that a relationship exists between muscle fatigue and intracellular accumulation of lactate. This reasoning is relevant to obstetrical issues. Myocytes in uterus work together during labor, and the contractions need to be strong and synchronized for a child to be delivered. At labor dystocia, the progress of labor becomes slow or arrested after a normal beginning. It has been described that, during labor dystocia, when the force of the contractions is low, the uterus is under hypoxia, and anaerobic conditions with high levels of lactate in amniotic fluid dominate. The purpose of this study was to examine whether myometrial cells are involved in the production of lactate in amniotic fluid and whether there are differences in production and distribution of lactate in cells incubated under aerobic and anaerobic conditions. We also wanted to elucidate the involvement of specific membrane-bound lactate carriers. Women undergoing elective caesarean section were included. Myometrial biopsies from uteri were collected and subjected to either immunohistochemistry to identify lactate carriers or in vitro experiments to analyze production of lactate. The presence of lactate carriers named monocarboxylate transporters 1 and 4 was verified. Myometrial cells produced lactate extracellularly, and the lactate carriers operated differently under anaerobic and aerobic conditions; while being mainly unidirectional under anaerobic conditions, they became bidirectional under aerobic conditions. Human myometrial cells produced and delivered lactate to the extracellular medium under both anaerobic and aerobic conditions. The delivery was mediated by lactate carriers.

Purpose of this Review: Even today, hundreds of thousands of women die or suffer high levels of morbidity associated with childbirth. One of the most common causes is halted labor progress, or labor dystocia. There have been no developments in the diagnosis or treatment of dystocic deliveries since Friedman designed the Partogram in the 1950s. Oxytocin is the only treatment for dystocic labor. Sometimes, oxytocin is a lifesaver for the woman, especially in severe postpartum hemorrhages. At the same time, it is also one of the most overused drugs in obstetric care. This review article is meant to provide a short overview of the current knowledge of uterine metabolism during labor, uterine lactate production, and its association with labor dystocia. The article also intends to reflect new ways of thinking regarding practical recommendations for treating labor dystocia and offer a look at the future of dystocic labor management. [ABSTRACT FROM AUTHOR]

Background: One of the major complications related to delivery is labor dystocia, or an arrested labor progress. Many dystocic deliveries end vaginally after administration of oxytocin, but a large numbers of women with labor dystocia will undergo a long and unsafe parturition. As a result of the exertion required in labor, the uterus produces lactate. The uterine production of lactate is mirrored by the level of lactate in amniotic fluid (AFL). Objectives: To evaluate whether the level of AFL, analysed in a sample of amniotic fluid collected vaginally at arrested labor when oxytocin was needed, could predict labor outcome in nulliparous deliveries. Methods: A prospective multicentre study including 3000 healthy primiparous women all with a singleton pregnancy, gestational age 37 to 42 weeks and no maternal /fetal chronic and/or pregnancy-related conditions. A spontaneous onset of labor, regular contractions and cervical dilation ≥ 3 cm were required before the women were invited to take part in the study. Results: AFL, analysed within 30 minutes before augmentation, provides information about delivery outcome. Sensitivity for an acute cesarean section according to high (≥10.1mmol/l) or low (< 10.1mmol/l) AFL values was 39.0% (95% CI; 27–50), specificity 90.3% (95% CI; 87–93) PPV 37.3% (95% CI; 27–48) and NPV was 91.0% (95% CI; 88–93). The overall percentage of correct predictions of delivery outcome when the AFL level was used was 83.7%. Deliveries with a high AFL-level correlated with delivery time >12h (p = 0.04), post-partum fever (>38°C, p = 0.01) and post-partum haemorrhage >1.5L (p = 0.04). Conclusion: The AFL is a good predictor of delivery outcome in arrested nulliparous deliveries. Low levels of AFL may support the decision to continue a prolonged vaginal labor by augmentation with oxytocin. A high level of AFL correlates with operative interventions and post-partum complications. [ABSTRACT FROM AUTHOR]

Objective To assess whether the frequency of adverse neonatal outcome at delivery is related to the level of lactate in amniotic fluid and to the use of oxytocin. Design Prospective observational study. Setting Soder Hospital, Stockholm, Sweden. Population Seventy-four women in active labor with a gestational age ≥36 weeks and mixed parity. Methods Levels of lactate in amniotic fluid were analyzed bedside from an intrauterine catheter every 30 min during labor. Deliveries were divided into groups with and without oxytocin. Main outcome measures The frequency of adverse neonatal outcome at delivery. Result Of the deliveries 13.5% (10/74) concluded with an adverse neonatal outcome. The levels of lactate in amniotic fluid increased during labor, more so in deliveries where oxytocin was used. In the group with an adverse neonatal outcome, the level of lactate in amniotic fluid was significantly higher in the final sample before delivery ( p = 0.04). In 18 deliveries, stimulation with oxytocin was temporarily halted for at least 30 min due to overly stimulated labor contractions. A decreasing level of lactate in amniotic fluid was shown within a median 5%/30 min. In the group where the administration of oxytocin was halted, there was no adverse neonatal outcome. Conclusion The frequency of adverse neonatal outcome was associated with the level of lactate in amniotic fluid and with the use of oxytocin. The level of lactate in amniotic fluid may be an additional valuable tool when oxytocin is administered during labor. [ABSTRACT FROM AUTHOR]

Abstract: Objective: Previous publications have suggested that high levels of lactate in amniotic fluid (AF) correlate with dysfunctional labor. The aim of this study was to investigate whether lactate concentration in AF together with the partogram is a better predictor of operative intervention in dysfunctional labor than the partogram alone. Study design: A prospective observational study was carried out of 825 laboring women. Samples of AF were collected and the lactate concentration was analyzed at the bedside during labor. The main outcome of the study was the method of delivery (operative/spontaneous vaginal) in relation to the concentration of lactate in AF. Logistic regression was used to estimate the association between lactate concentration in AF and labor outcome and to adjust for well-known risk factors for dysfunctional labor. Results: 385/825 women had an arrested labor according to the partogram, and 193 of them were delivered operatively. High lactate in AF (>10.1mmol/l) when labor arrested was associated with an increased risk of operative intervention due to dysfunctional labor (adjusted OR, 5.4, 95% CI, 3.2–9.1). Low levels of lactate in AF (<10.1mmol/l) were associated with an increased probability of spontaneous vaginal delivery (adjusted OR, 2.7, 95% CI, 1.7–4.8). Conclusion: The partogram together with the concentration of lactate in AF is a better predictor of operative intervention in dysfunctional labor than the partogram alone. [ABSTRACT FROM AUTHOR]

Objectives. To assess whether there is an association between high lactate concentration in amniotic fluid (AF) and labor dystocia. Design. Prospective observational study. Setting. Labor ward at General South Hospital, Stockholm, Sweden. Population and methods. Women in active labor attending labor ward, having at least two consecutive measurements of lactate concentration in AF, measured 60 minutes apart. Main outcome measure. Dysfunctional labor, defined as instrumental or operative delivery due to dystocia. Results. Among women with spontaneous vaginal deliveries (n=23) the mean lactate concentration in AF during labor was 8.9 mmol/l (range 6.6-10.8), and among women with operative delivery due to labor dystocia (n=31) the corresponding value was 10.9 mmol/l (range 8.0-16.1) (p<0.001). Of 29 women with a high lactate concentration (≥10.1 mmol/l) in at least two consecutive measures collected at least 60 minutes apart, 25 (86%) were delivered instrumentally/operatively due to dystocia. Using this definition of a positive test, the diagnostic accuracy to predict operative delivery due to dystocia was: sensitivity 81% (25/31), specificity 83% (19/23), positive predictive value 86% (25/29), and negative predictive value 76% (19/25). The likelihood ratio was 5.0 for a positive test and 0.2 for a negative test. Conclusions. High lactate concentration (≥10.1mmol/l) in at least two consecutive samples of AF collected during labor 60 minutes apart is strongly associated with dystocia. This method might be useful in clinical management to identify labor dystocia at an early stage of labor. [ABSTRACT FROM AUTHOR]

To assess whether lactate determination in vaginal fluids,‘Lac test’, can be used as a diagnostic test for prelabour rupture of membranes (PROM) and to derive the best cutoff value for a positive test.Prospective observational study.Labour ward at Söder Hospital in Stockholm, a large clinical service.Women living in the centre of Stockholm, the capital of Sweden.We selected 200 cases with a history of suspect PROM for determination of lactate concentrations in vaginal fluid. In 100 of these cases, actim PROM tests were also analysed.Sensitivity, specificity, positive and negative predictive values, likelihood ratios (LR) and Kappa indices in the identification of visible amniotic fluid at speculum examination.A lactate concentration≥4.5 mmol/L was found to be the best cutoff value for a positive test. The‘Lac test’ had a sensitivity of 86%, specificity 92%, positive and negative predictive values of 92% and 87%, respectively. Corresponding values for the actim PROM test were 60%, 98%, 97% and 71%. LR for a positive‘Lac test’ was 10.75 and for a negative test 0.15. Corresponding values for the PROM test were 30.0 and 0.4, respectively. The Kappa index was higher for the‘Lac test’ as compared with the actim PROM test (78% and 59%, respectively).Lactate determination is a valid test in cases with a history of suspect PROM and may even be a better predictor than the actim PROM test. [ABSTRACT FROM AUTHOR]