Multiple electrolyte derangements among perioperative women with obstructed labour in eastern Uganda: A cross-sectional study

There is a dearth of information on the patterns of electrolyte derangements among perioperative women with obstructed labour. We measured the levels and patterns of electrolyte derangements among women with obstructed labour in eastern Uganda. This was a secondary analysis of data for 389 patients with obstructed labour, diagnosed by either an obstetrician or medical officer on duty between July 2018 and June 2019. Five milliliters of venous blood was drawn from the antecubital fossa under an aseptic procedure for electrolytes and complete blood analyses. The primary outcome was the prevalence of electrolyte derangements, defined as values outside the normal ranges: Potassium 3.3-5.1 mmol/L, Sodium 130-148 mmol/L, Chloride 97-109 mmol/L, Magnesium 0.55-1.10 mmol/L, Calcium (Total) 2.05-2.42 mmol/L, and Bicarbonate 20-24 mmol/L. The most prevalent electrolyte derangement was hypobicarbonatemia [85.8% (334/389)], followed by hypocalcaemia [29.1% (113/389)], then hyponatremia [18% (70/389)]. Hyperchloraemia [4.1% (16/389)], hyperbicarbonatemia [3.1% (12/389)], hypercalcaemia [2.8% (11/389)] and hypermagnesemia [2.8% (11/389)] were seen in a minority of the study participants. A total of 209/389 (53.7%) of the participants had multiple electrolyte derangements. Women who used herbal medicines had 1.6 times the odds of having multiple electrolyte derangements as those who did not use herbal medicines [Adjusted Odds Ratio (AOR): 1.6; 95% Confidence Interval (CI): (1.0-2.5)]. Having multiple electrolyte derangements was associated with perinatal death although this estimate was not precise [AOR 2.1; 95% CI: (0.9-4.7)]. Women with obstructed labour in the perioperative period have multiple electrolyte derangements. Use of herbal medicines in labour was associated with having multiple electrolyte derangements. We recommend routine assessment of electrolytes prior to surgery in patients with obstructed labour.

The Pathophysiology of Labor Dystocia: Theme with Variations

Abnormally prolonged labor, or labor dystocia, is a common complication of parturition. It is the indication for about half of unplanned cesarean deliveries in low-risk nulliparous women. Reducing the rate of unplanned cesarean birth in the USA has been a public health priority over the last two decades with limited success. Labor dystocia is a complex disorder due to multiple causes with a common clinical outcome of slow cervical dilation and fetal descent. A better understanding of the pathophysiologic mechanisms of labor dystocia could lead to new clinical opportunities to increase the rate of normal vaginal delivery, reduce cesarean birth rates, and improve maternal and neonatal health. We conducted a literature review of the causes and pathophysiologic mechanisms of labor dystocia. We summarize known mechanisms supported by clinical and experimental data and newer hypotheses with less supporting evidence. We review recent data on uterine preparation for labor, uterine contractility, cervical preparation for labor, maternal obesity, cephalopelvic disproportion, fetal malposition, intrauterine infection, and maternal stress. We also describe current clinical approaches to preventing and managing labor dystocia. The variation in pathophysiologic causes of labor dystocia probably limits the utility of current general treatment options. However, treatments targeting specific underlying etiologies could be more effective. We found that the pathophysiologic basis of labor dystocia is under-researched, offering wide opportunities for translational investigation of individualized labor management, particularly regarding uterine metabolism and fetal position. More precise diagnostic tools and individualized therapies for labor dystocia might lead to better outcomes. We conclude that additional knowledge of parturition physiology coupled with rigorous clinical evaluation of novel biologically directed treatments could improve obstetric quality of care.

High Burden of Neurodevelopmental Delay among Children Born to Women with Obstructed Labour in Eastern Uganda: A Cohort Study

Over 250 million infants in low and middle-income countries do not fulfill their neurodevelopment potential. In this study, we assessed the incidence and risk factors for neurodevelopmental delay (NDD) among children born following obstructed labor in Eastern Uganda. Between October 2021 and April 2022, we conducted a cohort study of 155 children (aged 25 to 44 months), born at term and assessed their neurodevelopment using the Malawi Developmental Assessment Tool. We assessed the gross motor, fine motor, language and social domains of neurodevelopment. The incidence of neurodevelopmental delay by 25 to 44 months was 67.7% (105/155) (95% CI: 59.8-75.0). Children belonging to the poorest wealth quintile had 83% higher risk of NDD compared to children belonging to the richest quintile (ARR (Adjusted Risk Ratio): 1.83; 95% CI (Confidence Interval): [1.13, 2.94]). Children fed the recommended meal diversity had 25% lower risk of neurodevelopmental delay compared to children who did not (ARR: 0.75; 95% CI: [0.60, 0.94]). Children who were exclusively breastfed for the first 6 months had 27% lower risk of neurodevelopmental delay compared to children who were not (ARR: 0.73; 95% CI: [0.56, 0.96]). We recommend that infants born following obstructed labor undergo neurodevelopmental delay screening.

Oxytocin receptor DNA methylation is associated with exogenous oxytocin needs during parturition and postpartum hemorrhage

BACKGROUND

The oxytocin receptor gene (OXTR) is regulated, in part, by DNA methylation. This mechanism has implications for uterine contractility during labor and for prevention or treatment of postpartum hemorrhage, an important contributor to global maternal morbidity and mortality.

METHODS

We measured and compared the level of OXTR DNA methylation between matched blood and uterine myometrium to evaluate blood as an indicator of uterine methylation status using targeted pyrosequencing and sites from the Illumina EPIC Array. Next, we tested for OXTR DNA methylation differences in blood between individuals who experienced a postpartum hemorrhage arising from uterine atony and matched controls following vaginal birth. Bivariate statistical tests, generalized linear modeling and Poisson regression were used in the analyses.

RESULTS

Here we show a significant positive correlation between blood and uterine DNA methylation levels at several OXTR loci. Females with higher OXTR DNA methylation in blood had required significantly more exogenous oxytocin during parturition. With higher DNA methylation, those who had oxytocin administered during labor had significantly greater relative risk for postpartum hemorrhage (IRR 2.95, 95% CI 1.53-5.71).

CONCLUSIONS

We provide evidence that epigenetic variability in OXTR is associated with the amount of oxytocin administered during parturition and moderates subsequent postpartum hemorrhage. Methylation can be measured using a peripheral tissue, suggesting potential use in identifying individuals susceptible to postpartum hemorrhage. Future studies are needed to quantify myometrial gene expression in connection with OXTR methylation.

Preserved oxytocin-induced myometrium contraction and sensitivity to progesterone inhibition following rat uterus thermal insult. Impact on fertility

Women seeking improved fertility often undergo diagnostic hysteroscopy that could cause uterine thermal injury with unclear impact on uterine contraction, embryo implantation and fertility. We tested whether uterine thermal insult adversely affects myometrium function and contraction related receptors, channels, junctional proteins and remodeling enzymes. Female Sprague-Dawley rats were anesthetized, the left uterine horn was infused with 85 ℃ hot saline (thermal Insult) and the right horn was infused with 25℃ warm saline (control) for 3 min. After 7-days recovery, uterine strips were prepared for tissue histology and measurement of contraction, and mRNA and protein levels of oxytocin receptor, progesterone (P4) receptor A (PR-A), membrane K⁺ channel TREK-1, junctional protein connexin-43 (CX-43) and matrix metalloproteinases MMP-2 and MMP-9. Uterine tissue histology showed cellular swelling and inflammatory cell infiltration immediately following thermal insult, and recovery with no difference from control 7-days later. KCl (96 mM) and oxytocin (10^-13-10^-7 M) caused significant contraction that was not different in thermal insult vs control uterine strips. Pretreatment with P4 (10^-5 M) for 1 h caused marked inhibition of KCl and oxytocin contraction that was insignificantly greater in thermal vs control uterus. RT-PCR showed decreases in oxytocin receptor, PR-A, TREK-1, CX-43, MMP-2 and MMP-9 mRNA in thermal vs control uterus. Western blots showed decreases in oxytocin receptor, no change in TREK-1 and increased PRA, CX-43, MMP-2, and MMP-9 protein levels in thermal vs control uterus. To assess the impact on fertility, female rats were housed with male rats, and on gestational day 19, the litter size, pup weight and crown-rump length, and placenta weight were not different in thermal vs control uterus. Thus, after thermal insult-induced immediate inflammation and reduced heat-sensitive mRNA expression, the uterus undergoes a recovery and adaptation process involving preserved oxytocin-induced contraction, P4 inhibition and TREK-1 channels. The uterus self-healing process appears to require improved PR-A signaling, intercellular communication via CX-43 and tissue remodeling by MMP-2 and MMP-9. The uterine thermal recovery processes could be essential for maintaining fertility and future pregnancy outcome.

Using Pen-Side Measurable Blood Parameters to Predict or Identify Dystocic Lambing Events

Simple Summary

Prolonged or non-progressive labour is the greatest risk factor for loss of newborn lambs in Australia and poses significant welfare and economic concerns worldwide. In this study, we set out to investigate whether pen-side technology could be used to predict which ewes would be at risk of prolonged labour. In our pilot trial, we found potentially useful markers. We next developed a sampling protocol by looking at changes in candidate markers over time in normal lambing events. Finally, we searched for blood markers that could distinguish between normal and difficult lambing events, sampling pre-birth (estimated one week before birth), at birth (within 3 h) and post-birth (16–26 h). Possible predictors of lambing difficulty were chloride, haematocrit and haemoglobin, sampled one week before birth; creatinine, sampled at birth; and acid–base related parameters after birth. In conclusion, we found that pen-side analysis of blood markers showed promise in identifying dystocic lambing events. More information is required to decide whether pen-side diagnostics could be useful to identify and predict dystocic lambing in the future.

Abstract

Dystocia is the greatest contributor to neonatal lamb mortality in Australia and poses significant welfare and economic concerns worldwide. In this study, we set out to investigate whether pen-side analysis technology could be employed to detect blood parameters predictive of dystocic labour events in sheep. In a pilot trial, we collected and analysed blood samples in pen-side assays for glucose, lactate, pH, pCO₂, pO₂, base excess, HCO₃, TCO₂, sO₂, lactate, sodium, potassium, chloride, calcium, urea nitrogen, creatinine, haematocrit, haemoglobin and anion gap. From the pilot data, we identified creatinine, TCO₂, chloride and calcium as potentially useful markers. To develop a time course and to establish variability of the selected blood parameters, a time series of samples was collected from 12 ewes, from mid-gestation to 48 h after birth. For the main trial, blood samples were collected at mid- and late gestation for glucose determination and for the full set of blood parameters at three time points before, at and after birth. Possible predictors of lambing difficulty were chloride, haematocrit and haemoglobin, sampled one week before birth; creatinine, sampled at birth; and blood pH and base excess after birth. In conclusion, we found that pen-side analysis of blood markers showed promise in identifying dystocic lambing events.

Incidence and determinants of perinatal mortality among women with obstructed labour in eastern Uganda: a prospective cohort study

BACKGROUND

In Uganda, the incidence and determinants of perinatal death in obstructed labour are not well documented. We determined the incidence and determinants of perinatal mortality among women with obstructed labour in Eastern Uganda.

METHODS

Between July 2018 and September 2019, 584 with obstructed labour were recruited and followed up to the 7th day postnatal. Information on maternal characteristics, obstetric factors and laboratory parameters was collected. Each patient received the standard perioperative care. We used a generalized linear model for the Poisson family, with a log link and robust variance estimation to determine the association between the exposure variables and perinatal death.

RESULTS

Of the 623 women diagnosed with obstructed labour, 584 met the eligibility criteria. There were 24 fresh still births (FSB) and 32 early neonatal deaths (ENND) giving an FSB rate of 43.8 (95% CI 28.3-64.4) deaths per 1000 total births; early neonatal death rate of 58.4 (95% CI 40.3-81.4) deaths per 1000 and an overall perinatal mortality rate of 102.2 (95% CI 79.4-130.6) deaths in the first 7 days of life. A mother being referred in active labour adjusted risk ratio of 2.84 (95% CI: 1.35-5.96) and having high blood lactate levels at recruitment adjusted risk ratio 2.71 (95% CI: 1.26-4.24) were the determinants of perinatal deaths.

CONCLUSIONS

The incidence of perinatal death was four times the regional and national average. Babies to women referred in active labour and those with high maternal blood lactate were more likely to die.

Clinical evaluation of labor: an evidence- and experience-based approach

During labor mother and fetus are evaluated at intervals to assess their well-being and determine how the labor is progressing. These assessments require skillful physical diagnosis and the ability to translate the acquired information into meaningful prognostic decision-making. We describe a coordinated approach to the assessment of labor. Graphing of serial measurements of cervical dilatation and fetal station creates "labor curves," which provide diagnostic and prognostic information. Based on these curves we recognize nine discrete labor abnormalities. Many may be related to insufficient or disordered contractile mechanisms. Several factors are strongly associated with development of labor disorders, including cephalopelvic disproportion, excess analgesia, fetal malpositions, intrauterine infection, and maternal obesity. Clinical cephalopelvimetry involves assessing pelvic traits and predicting their effects on labor. These observations must be integrated with information derived from the labor curves. Exogenous oxytocin is widely used. It has a high therapeutic index, but is easily misused. Oxytocin treatment should be restricted to situations in which its potential benefits clearly outweigh its risks. This requires there be a documented labor dysfunction or a legitimate medical reason to shorten the labor. Normal labor and delivery pose little risk to a healthy fetus; but dysfunctional labors, especially if stimulated excessively by oxytocin or terminated by complex operative vaginal delivery, have the potential for considerable harm. Conscientiously implemented, the approach to the evaluation of labor outlined in this review will result in a reasonable cesarean rate and minimize risks that may accrue from the labor and delivery process.

Effect of pre-operative bicarbonate infusion on maternal and perinatal outcomes among women with obstructed labour in Mbale hospital: A double blind randomized controlled trial

INTRODUCTION

Oral bicarbonate solution is known to improve both maternal and perinatal outcomes among women with abnormal labour (dystocia). Its effectiveness and safety among women with obstructed labour is not known.

OBJECTIVE

To determine the effect and safety of a single-dose preoperative infusion of sodium bicarbonate on maternal and fetal blood lactate and clinical outcomes among women with obstructed labour (OL) in Mbale hospital.

METHODS

We conducted a double blind, randomised controlled trial from July 2018 to September 2019. The participants were women with OL at term (≥37 weeks gestation), carrying a singleton pregnancy with no other obstetric emergency, medical comorbidity or laboratory derangements.

INTERVENTION

A total of 477 women with OL were randomized to receive 50ml of 8.4% sodium bicarbonate (238 women) or 50 mL of 0.9% sodium chloride (239 women). In both the intervention and controls arms, each participant was preoperatively given a single dose intravenous bolus. Every participant received 1.5 L of normal saline in one hour as part of standard preoperative care.

OUTCOME MEASURES

Our primary outcome was the mean difference in maternal venous blood lactate at one hour between the two arms. The secondary outcomes were umbilical cord blood lactate levels at birth, neonatal sepsis and early neonatal death upto 7 days postnatal, as well as the side effects of sodium bicarbonate, primary postpartum hemorrhage, maternal sepsis and mortality at 14 days postpartum.

RESULTS

The median maternal venous lactate was 6.4 (IQR 3.3-12.3) in the intervention and 7.5 (IQR 4.0-15.8) in the control group, with a statistically non-significant median difference of 1.2 mmol/L; p-value = 0.087. Vargha and Delaney effect size was 0.46 (95% CI 0.40-0.51) implying very little if any effect at all.

CONCLUSION

The 4.2g of preoperative intravenous sodium bicarbonate was safe but made little or no difference on blood lactate levels.

TRIAL REGISTRATION

PACTR201805003364421.

Activation of Autophagy in Human Uterine Myometrium During Labor

OBJECTIVE

The purpose of this study was to analyze the autophagy of the human uterine myometrium during the labor.

METHODS

We collected uterine myometrium strips from term, singleton, nulliparous healthy women undergoing cesarean delivery before labor (nonlabor group, n = 10) or during normal labor (in-labor group, n = 10) without rupturing of membrane. The indications for cesarean delivery were breech presentation or maternal request. Transmission electron microscopy was used to observe autophagosomes. Reverse transcriptase polymerase chain reaction, immunofluorescence, and Western blot were used to quantify the messenger RNA (mRNA) and protein level of the autophagy markers LC3B, P62, and Beclin-1 in the uterine muscle strips.

RESULTS

There were no differences between both groups in maternal age, body mass index, gestational week, neonatal weight, operative bleeding, and postpartum bleeding. Transmission electron micrographs showed that autophagosomes existed in myometrial tissue in both groups. There were more autophagosomes in the in-labor group than in the nonlabor group, and the difference had significance. The in-labor group had significantly greater LC3B mRNA expression but significantly lower P62 mRNA expression compared with the nonlabor group. Semiquantitative immunofluorescence in uterine myometrial cells in the in-labor group showed increased LC3B puncta formation and greater Beclin-1 expression but reduced P62 puncta formation compared with the nonlabor group. The ratio of LC3BII/I proteins was significantly higher, but P62 protein was significantly lower in the in-labor group compared with the nonlabor group. The Beclin-1 mRNA and protein expressions were not significantly different between the 2 groups.

CONCLUSION

Autophagy was activated in human uterine myometrium during labor and might play an important role in maintaining uterine contraction function.

Amniotic fluid lactate level as a diagnostic tool for prolonged labour

Prolonged labour can lead to postpartum complications and adverse outcomes for both mother and baby. Measurable parameters can help in the active management of labour, timely diagnosis of dystocia and in the choice of the method of delivery. Progressive uterine contractions are necessary to complete labour successfully. Myometrial fatigue during prolonged labour causes a change from aerobic to anaerobic metabolism, resulting in an accumulation of intramuscular lactic acid and probably a subsequent increase in amniotic fluid lactate concentration. High amniotic fluid lactate level has been associated with ineffective uterine contractions leading to labour arrest. A considerable number of studies conducted so far indicate that the level of lactate in amniotic fluid may be a new non-invasive diagnostic tool for early prediction of prolonged labour and the need for immediate obstetric intervention. Low amniotic fluid lactate level may facilitate a decision to continue vaginal labour by oxytocin augmentation. A high level of amniotic fluid lactate is associated with surgical obstetric procedures. Measuring amniotic fluid lactate level might simplify the patient's allocation to a group, which will benefit from the administration of oxytocin and to a group that will not benefit from further prolongation of labour. This study aimed to briefly review current knowledge on amniotic fluid lactate concentrations measured using standard biochemical methods during the first stage of labour following normal pregnancy, as a possible diagnostic tool for prolonged labour. For this purpose, PubMed, EMBASE, Medline (1990 to July 2020) trials register and reference lists of relevant articles were searched.

Human Uterine Biopsy: Research Value and Common Pitfalls

The human uterus consists of the inner endometrium, the myometrium, and the outer serosa. Knowledge of the function of the uterus in health and disease is relevant to reproduction, fertility, embryology, gynaecology, endocrinology, and oncology. Research performed on uterine biopsies is essential to further the current understanding of human uterine biology. This brief review explores the value of the uterine biopsy in gynaecological and human fertility research and explores the common problems encountered when analysing data generated from different types of uterine biopsies, with the aim of improving the quality, reproducibility, and clinical translatability of future research.

Analysis of in vivo uterine peristalsis in the non-pregnant female mouse

Uterine peristalsis due to spontaneous contractions of the myometrial smooth muscles has important roles in pre-implantation processes of intra-uterine sperm transport to the fertilization site, and then embryo transport to the implantation sites. We developed a new objective methodology to study in vivo uterine peristalsis in female mice during the pro-oestrus phase. The acquisition procedure of the uterine organ is remote without interfering with the organ function. The uniqueness of the new approach is that video images of physiological pattern were converted using image processing and new algorithms to biological time-dependent signals that can be processed with existing algorithms for signal processing. Using this methodology we found that uterine peristalsis in the pro-oestrus mouse is in the range of 0.008-0.029 Hz, which is about one contraction per minute and with fairly symmetric contractions that occasionally propagate caudally. This rate of contractions is similar to that of human uterine peristalsis acquired in vivo, which is important information for a popular animal model.

Effect of preoperative bicarbonate infusion on maternal and perinatal outcomes of obstructed labour in Mbale Regional Referral Hospital: a study protocol for a randomised controlled trial

INTRODUCTION

To improve maternal and fetal outcomes among patients with obstructed labour (OL) in low-resource settings, the associated electrolyte and metabolic derangements must be adequately corrected. Oral fluid intake during labour and preoperative intravenous fluid replacement following OL corrects the associated dehydration and electrolyte changes, but it does not completely reverse the metabolic acidosis, that is, a cause of intrapartum birth asphyxia and a risk factor for primary postpartum haemorrhage due to uterine atony. Sodium bicarbonate is a safe, effective, cheap and readily available acid buffer, that is widely used by sportspeople to improve performance. It also appears to improve fetal and maternal outcomes in abnormally progressing labour. However, its effects on maternal and fetal outcomes among patients with OL is unknown. We aim at establishing the effect of a single-dose preoperative infusion of sodium bicarbonate on maternal and fetal lactate levels and clinical outcomes among patients with OL.

METHODS AND ANALYSIS

This will be a double blind, randomised controlled clinical phase IIb trial. We will randomise 478 patients with OL to receive either 50 mL of placebo with standard preoperative infusion of normal saline (1.5 L) or 4.2 g of sodium bicarbonate solution (50 mL of 50 mmol/L) with the preoperative infusion of normal saline (1.5 L). The primary outcome will be mean lactate levels in maternal capillary blood at 1 hour after study drug administration and in the arterial cord blood at birth. We will use the intention-to-treat analysis approach. Secondary outcomes will include safety, maternal and fetal morbidity and mortality up to 14 days postpartum.

ETHICS AND DISSEMINATION

Makerere University School of Medicine Research and Ethics Committee and Uganda National Council for Science and Technology have approved the protocol. Each participant will give informed consent at enrollment.

TRIAL REGISTRATION NUMBER

PACTR201805003364421.

Activation of Autophagy in Human Uterine Myometrium During Labor

OBJECTIVE:

The purpose of this study was to analyze the autophagy of the human uterine myometrium during the labor.

METHODS:

We collected uterine myometrium strips from term, singleton, nulliparous healthy women undergoing cesarean delivery before labor (nonlabor group, n = 10) or during normal labor (in-labor group, n = 10) without rupturing of membrane. The indications for cesarean delivery were breech presentation or maternal request. Transmission electron microscopy was used to observe autophagosomes. Reverse transcriptase polymerase chain reaction, immunofluorescence, and Western blot were used to quantify the messenger RNA (mRNA) and protein level of the autophagy markers LC3B, P62, and Beclin-1 in the uterine muscle strips.

RESULTS:

There were no differences between both groups in maternal age, body mass index, gestational week, neonatal weight, operative bleeding, and postpartum bleeding. Transmission electron micrographs showed that autophagosomes existed in myometrial tissue in both groups. There were more autophagosomes in the in-labor group than in the nonlabor group, and the difference had significance. The in-labor group had significantly greater LC3B mRNA expression but significantly lower P62 mRNA expression compared with the nonlabor group. Semiquantitative immunofluorescence in uterine myometrial cells in the in-labor group showed increased LC3B puncta formation and greater Beclin-1 expression but reduced P62 puncta formation compared with the nonlabor group. The ratio of LC3BII/I proteins was significantly higher, but P62 protein was significantly lower in the in-labor group compared with the nonlabor group. The Beclin-1 mRNA and protein expressions were not significantly different between the 2 groups.

CONCLUSION:

Autophagy was activated in human uterine myometrium during labor and might play an important role in maintaining uterine contraction function.

A computational model of excitation and contraction in uterine myocytes from the pregnant rat

Aberrant uterine myometrial activities in humans are major health issues. However, the cellular and tissue mechanism(s) that maintain the uterine myometrium at rest during gestation, and that initiate and maintain long-lasting uterine contractions during delivery are incompletely understood. In this study we construct a computational model for describing the electrical activity (simple and complex action potentials), intracellular calcium dynamics and mechanical contractions of isolated uterine myocytes from the pregnant rat. The model reproduces variant types of action potentials - from spikes with a smooth plateau, to spikes with an oscillatory plateau, to bursts of spikes - that are seen during late gestation under different physiological conditions. The effects of the hormones oestradiol (via reductions in calcium and potassium selective channel conductance), oxytocin (via an increase in intracellular calcium release) and the tocolytic nifedipine (via a block of L-type calcium channels currents) on action potentials and contractions are also reproduced, which quantitatively match to experimental data. All of these results validated the cell model development. In conclusion, the developed model provides a computational platform for further investigations of the ionic mechanism underlying the genesis and control of electrical and mechanical activities in the rat uterine myocytes.

Adaptive reduction of human myometrium contractile activity in response to prolonged uterine stretch during term and twin pregnancy. Role of TREK-1 channel

Quiescence of myometrium contractile activity allows uterine expansion to accommodate the growing fetus and prevents preterm labor particularly during excessive uterine stretch in multiple pregnancy. However, the mechanisms regulating uterine response to stretch are unclear. We tested the hypothesis that prolonged uterine stretch is associated with decreased myometrium contractile activity via activation of TWIK-related K⁺ channel (TREK-1). Pregnant women at different gestational age (preterm and term) and uterine stretch (singleton and twin pregnancy) were studied, and uterine strips were isolated for measurement of contractile activity and TREK-1 channel expression/activity. Both oxytocin- and KCl-induced contraction were reduced in term vs preterm pregnancy and in twin vs singleton pregnancy. Oxytocin contraction was reduced in uterine segments exposed to 8 g stretch compared to control tissues under 2 g basal tension. TREK-1 mRNA expression and protein levels were augmented in Singleton-Term vs Singleton-Preterm, and in uterine strips exposed to 8 g stretch. The TREK-1 activator arachidonic acid reduced oxytocin contraction in preterm and term, singleton and twin pregnant uterus. The TREK-1 blocker l-methionine enhanced oxytocin contraction in Singleton-Term and twin pregnant uterus, and reversed the decreases in contraction in uterine strips exposed to prolonged stretch. Carboprost-induced uterine contraction was also reduced by arachidonic acid and enhanced by l-methionine. Thus, myometrium contraction decreases with gestational age and uterine expansion in twin pregnancy. The results suggest that prolonged stretch enhances the expression/activity of TREK-1 channel, leading to decreased myometrium contractile activity and maintained healthy term pregnancy particularly in multiple pregnancy.

Biomechanics of the human uterus

The appropriate biomechanical function of the uterus is required for the execution of human reproduction. These functions range from aiding the transport of the embryo to the implantation site, to remodeling its tissue walls to host the placenta, to protecting the fetus during gestation, to contracting forcefully for a safe parturition and postpartum, to remodeling back to its nonpregnant condition to renew the cycle of menstruation. To serve these remarkably diverse functions, the uterus is optimally geared with evolving and contractile muscle and tissue layers that are cued by chemical, hormonal, electrical, and mechanical signals. The relationship between these highly active biological signaling mechanisms and uterine biomechanical function is not completely understood for normal reproductive processes and pathological conditions such as adenomyosis, endometriosis, infertility and preterm labor. Animal studies have illuminated the rich structural function of the uterus, particularly in pregnancy. In humans, medical imaging techniques in ultrasound and magnetic resonance have been combined with computational engineering techniques to characterize the uterus in vivo, and advanced experimental techniques have explored uterine function using ex vivo tissue samples. The collective evidence presented in this review gives an overall perspective on uterine biomechanics related to both its nonpregnant and pregnant function, highlighting open research topics in the field. Additionally, uterine disease and infertility are discussed in the context of tissue injury and repair processes and the role of computational modeling in uncovering etiologies of disease. WIREs Syst Biol Med 2017, 9:e1388. doi: 10.1002/wsbm.1388 For further resources related to this article, please visit the WIREs website.

Lactate produced during labor modulates uterine inflammation via GPR81 (HCA1)

BACKGROUND

Uterine inflammatory processes trigger prolabor pathways and orchestrate on-time labor onset. Although essential for successful labor, inflammation needs to be regulated to avoid uncontrolled amplification and resolve postpartum. During labor, myometrial smooth muscle cells generate ATP mainly via anaerobic glycolysis, resulting in accumulation of lactate. Aside from its metabolic function, lactate has been shown to activate a G protein-coupled receptor, GPR81, reported to regulate inflammation. We therefore hypothesize that lactate produced during labor may act via GPR81 in the uterus to exert in a feedback manner antiinflammatory effects, to resolve or mitigate inflammation.

OBJECTIVE

We sought to investigate the role of lactate produced during labor and its receptor, GPR81, in regulating inflammation in the uterus.

STUDY DESIGN

We investigated the expression of GPR81 in the uterus and the pharmacological role of lactate acting via GPR81 during labor, using shRNA-GPR81 and GPR81^-/- mice.

RESULTS

(1) Uterine lactate levels increased substantially from 2 to 9 mmol/L during labor. (2) Immunohistological analysis revealed expression of GPR81 in the uterus with high expression in myometrium. (3) GPR81 expression increased during gestation, and peaked near labor. (4) In primary myometrial smooth muscle cell and ex vivo uteri from wild-type mice, lactate decreased interleukin-1β-induced transcription of key proinflammatory Il1b, Il6, Ccl2, and Pghs2; suppressive effects of lactate were not observed in cells and tissues from GPR81^-/- mice. (5) Conversely, proinflammatory gene expression was augmented in the uterus at term in GPR81^-/- mice and wild-type mice treated intrauterine with lentiviral-encoded shRNA-GPR81; GPR81 silencing also induced proinflammatory gene transcription in the uterus when labor was induced by endotoxin (lipopolysaccharide). (6) Importantly, administration to pregnant mice of a metabolically stable specific GPR81 agonist, 3,5-dihydroxybenzoic acid, decreased endotoxin-induced uterine inflammation, preterm birth, and associated neonatal mortality.

CONCLUSION

Collectively, our data uncover a novel link between the anaerobic glycolysis and the control of uterine inflammation wherein the high levels of lactate produced during labor act on uterine GPR81 to down-regulate key proinflammatory genes. This discovery may represent a novel feedback mechanism to regulate inflammation during labor, and conveys a potential rationale for the use of GPR81 agonists to attenuate inflammation and resulting preterm birth.

Gut microbial metabolism defines host metabolism: an emerging perspective in obesity and allergic inflammation

The presence of >100 trillion microorganisms (collectively called gut microbiota) in our large intestine is essential for the maintenance of health. The gut microbiota starts to develop before birth and matures within first three years of life. The Western diet and lifestyle have been implicated in causing an imbalance of gut microbial communities and their metabolites that consequence in disease states, such as obesity and asthma. With more than 13% of the world population currently living with obesity and one out of 10 children diagnosed with asthma, we explore here the recent developments in the biosynthesis and mode of action of the key metabolites in relation to these two chronic inflammatory conditions.

Association between Maternal Pelvis Height and Intrapartum Foetal Head Moulding in Ugandan Mothers with Spontaneous Vertex Deliveries

Introduction. In Sub-Saharan Africa, excessive foetal head moulding is commonly associated with cephalopelvic disproportion and obstructed labour. This study set out to determine the associations of maternal pelvis height and maternal height with intrapartum foetal head moulding. Methods. This was a multisite secondary analysis of maternal birth records of mothers with singleton pregnancies ending in a spontaneous vertex delivery. A summary of the details of the pregnancy and delivery records were reviewed and analysed using multilevel logistic regression respect to foetal head moulding. The alpha level was set at P < 0.05. Results. 412 records were obtained, of which 108/385 (28%) observed foetal head moulding. There was a significant reduction in risk of foetal head moulding with increasing maternal height (Adj. IRR 0.97, P = 0.05), maternal pelvis height (Adj. IRR 0.88, P < 0.01), and raptured membranes (Adj. IRR 0.10, P < 0.01). There was a significant increased risk of foetal head moulding with increasing birth weight (Adj. IRR 1.90, P < 0.01) and duration of monitored active labour (Adj. IRR 1.21, P < 0.01) in the final model. Conclusion. This study showed that increasing maternal height and maternal pelvis height were associated with a significant reduction in intrapartum foetal head moulding.

Insights from physiology into myometrial function and dysfunction

NEW FINDINGS

What is the topic of this review? I focus on clinical aspects of uterine physiology, specifically, myometrial contractility. I bring together and contrast findings using physiological approaches and those using newer techniques, 'omics'. What advances does it highlight? Physiological studies have recently shed light on the myometrium in twin pregnancies, but there have been no 'omic' approaches. In contrast, studies of preterm delivery using newer approaches are generating new research avenues, whereas traditional approaches have not flourished. Finally, I describe significant advances in understanding of 'slow-to-progress' labours, achieved using physiological and clinical approaches. Advances in molecular, genetic and 'omic' technologies are fuelling the thirst for better understanding of the uterus and application of this information to problems in pregnancy and labour. Progress has, however, been limited while we still have an incomplete understanding of some of the basic physiology of uterine smooth muscle (myometrium). In this review and opinion piece, I explore some of the fascinating findings from selected recent studies and see how these may provide new avenues for physiological and clinical research. It is also the case, however, that there is still limited mechanistic understanding about physiological and pathophysiological processes in the myometrium. This lack of understanding limits the usefulness of some findings from genomic and allied studies. By focusing on some key recent findings and relating these to two important clinical problems in childbirth that involve myometrial activity, namely preterm delivery and difficult labours, the interplay between our physiological knowledge and the information provided by newer technologies is explored. My opinion is that physiology has provided much more new mechanistic insight into difficult births and that the newer technologies may lead to breakthroughs in preterm birth research, but that this has not yet happened.