Fetal and maternal energy metabolism during labor in relation to the available caloric substrate

A Critical Review on the Opportunity to Use Placenta and Innovative Biomonitoring Methods to Characterize the Prenatal Chemical Exposome

Adverse effects associated with chemical exposures during pregnancy include several developmental and reproductive disorders. However, considering the tens of thousands of chemicals present on the market, the effects of chemical mixtures on the developing fetus is still likely underestimated. In this critical review, we discuss the potential to apply innovative biomonitoring methods using high-resolution mass spectrometry (HRMS) on placenta to improve the monitoring of chemical exposure during pregnancy. The physiology of the placenta and its relevance as a matrix for monitoring chemical exposures and their effects on fetal health is first outlined. We then identify several key parameters that require further investigations before placenta can be used for large-scale monitoring in a robust manner. Most critical is the need for standardization of placental sampling. Placenta is a highly heterogeneous organ, and knowledge of the intraplacenta variability of chemical composition is required to ensure unbiased and robust interindividual comparisons. Other important variables include the time of collection, the sex of the fetus, and mode of delivery. Finally, we discuss the first applications of HRMS methods on the placenta to decipher the chemical exposome and describe how the use of placenta can complement biofluids collected on the mother or the fetus.

The amniotic fluid proteome changes with term labor and informs biomarker discovery in maternal plasma

The intra-uterine components of labor, namely, myometrial contractility, cervical ripening, and decidua/membrane activation, have been extensively characterized and involve a local pro-inflammatory milieu of cellular and soluble immune mediators. Targeted profiling has demonstrated that such processes extend to the intra-amniotic space, yet unbiased analyses of the proteome of human amniotic fluid during labor are lacking. Herein, we utilized an aptamer-based platform to characterize 1,310 amniotic fluid proteins and found that the proteome undergoes substantial changes with term labor (251 proteins with differential abundance, q < 0.1, and fold change > 1.25). Proteins with increased abundance in labor are enriched for immune and inflammatory processes, consistent with prior reports of labor-associated changes in the intra-uterine space. By integrating the amniotic fluid proteome with previously generated placental-derived single-cell RNA-seq data, we demonstrated the labor-driven upregulation of signatures corresponding to stromal-3 and decidual cells. We also determined that changes in amniotic fluid protein abundance are reflected in the maternal plasma proteome. Collectively, these findings provide novel insights into the amniotic fluid proteome in term labor and support its potential use as a source of biomarkers to distinguish between true and false labor by using maternal blood samples.

Time Course Analysis of Transcriptome in Human Myometrium Depending on Labor Duration and Correlating With Postpartum Blood Loss

The maintenance of coordinated powerful episodic contractions of the uterus is the crucial factor for normal labor. The uterine contractility is gradually enhanced with the progression of labor, which is related to the gene expression of the myometrium. Competing endogenous RNA (ceRNA) can also regulate the gene expression. To better understand the role of ceRNA network in labor, transcriptome sequencing was performed on the myometrium of 17 parturients at different labor durations (0–24 h). From this, expression levels of mRNA, long non-coding RNA (lncRNA), circular RNA (circRNA), and microRNA (miRNA) were correlated with labor duration. Then, targeting relationships between mRNAs, lncRNAs, circRNAs, and miRNAs were predicted, and the ceRNA regulatory network was established. The mRNA expression patterns associated with cervical dilation and postpartum bleeding were further investigated. This analysis identified 932 RNAs positively correlated with labor duration (859 mRNAs, 28 lncRNAs, and 45 circRNAs) and 153 RNAs negatively correlated with labor duration (122 mRNAs, 28 lncRNAs, and 3 miRNAs). These mRNAs were involved in protein metabolism, transport, and cytoskeleton functions. According to the targeting relationship among these ceRNAs and mRNAs, a ceRNA network consisting of 3 miRNAs, 72 mRNAs, 2 circRNAs, and 1 lncRNA was established. In addition, two mRNA expression patterns were established using time-series analysis of mRNA expression in different phases of cervical dilation. A ceRNA network analysis for blood loss was performed; postpartum bleeding was closely related to inflammatory response, angiogenesis, and hemostasis. This study identified human myometrial transcriptome and established the ceRNA regulatory network depending on labor duration and highlighted the dynamic changes that occur at ceRNAs during parturition, which need to be considered more in the future to better understand how changes in gene expression are relevant to functional changes in human myometrium at labor.

A double-blinded randomized controlled trial on the effects of increased intravenous hydration in nulliparas undergoing induction of labor

BACKGROUND

Rates of labor induction are increasing, raising concerns related to increased healthcare utilization costs. High-dose intravenous fluid (250 cc/h) has been previously demonstrated to shorten the time to delivery in nulliparous individuals in spontaneous labor. Whether or not this relationship exists among individuals undergoing induction of labor is unknown.

OBJECTIVE

Our study aimed to evaluate the effect of high-dose intravenous hydration on time to delivery among nulliparous individuals undergoing induction of labor.

STUDY DESIGN

Nulliparous individuals presenting for induction of labor with a Bishop score of ≤6 (with and without rupture of membranes) were randomized to receive either 125 cc/h or 250 cc/h of normal saline. The primary outcome was length of labor (defined as time from initiation of study fluids to delivery). Both time to overall delivery and vaginal delivery were evaluated. Secondary outcomes included the lengths of each stage of labor, the percentage of individuals delivering within 24 hours, and maternal and neonatal outcomes, including cesarean delivery rate.

RESULTS

A total of 180 individuals meeting inclusion criteria were enrolled and randomized. Baseline demographic characteristics were similar between groups; however, there was a higher incidence of diabetes mellitus in the group receiving 125 cc/h. Average length of labor was similar between groups (27.6 hours in 250 cc/h and 27.8 hours in 125 cc/h), as was the length of each stage of labor. Cox regression analysis did not demonstrate an effect of fluid rate on time to delivery. Neither the admission Bishop score, body mass index, nor other demographic characteristics affected time to delivery or vaginal delivery. There were no differences in maternal or neonatal outcomes, including overall cesarean delivery rate, clinically apparent iatrogenic intraamniotic infection, Apgar scores, need for neonatal phototherapy, or neonatal intensive care unit stay.

CONCLUSION

There were no observed differences in the length of labor or maternal or neonatal outcomes with the administration of an increased rate of intravenous fluids among nulliparous individuals undergoing induction of labor.

[Normal childbirth: physiologic labor support and medical procedures. Guidelines of the French National Authority for Health (HAS) with the collaboration of the French College of Gynaecologists and Obstetricians (CNGOF) and the French College of Midwives (CNSF) - Mother's wellbeing and regional or systemic analgesia for labor]

INTRODUCTION

These guidelines deal with the parturient wellbeing in terms of hydration and regional and systemic pain management during labour.

METHOD

Guidelines were established based on literature analysis and experts consensus.

RESULTS

Clear liquids consumption is permitted all along labor and postpartum, without volume limitation, in patients at low risk of general anesthesia (grade B). The consumption of solid foods is not recommended during the active stage of labor (consensus agreement). It is recommended to promote on regional analgesia to prevent inhalation (grade A). Pain relief using regional analgesia is a part of normal childbirth. It is recommended to provide regional analgesia to parturient who wish these technics. Regional analgesia is the safest and most effective analgesic method for the mother (grade A) and the child (grade B). It is recommended to inform women on the analgesic technics, to respect their choice and consider the right for a parturient to change her strategy in obstetrical circumstances or in cases of untractable pain (consensus agreement). It is recommended to perform a "low-dose" regional analgesia that respects the experience of childbirth (grade A) and maintain it with a patient controlled epidural analgesia technics (grade A). There is no minimum cervical dilation to allow epidural analgesia (grade A). In cases of rapid labor or after delivery for revision, spinal or combined spinal epidural can be used (grade C). Epidural has not to be ended before birth (consensus agreement). Blood pressure and fetal heart rate must be monitored every 3minutes after induction and/or each 10mL bolus then hourly (consensus agreement). Systematic and preventive fluid loading is not needed if only due to regional analgesia (grade B). Deambulation or postures are allowed in the absence of motor block and must be traced and do not alter the distribution of the regional analgesia (grade C). The postures of childbirth do not alter regional analgesia spread (NP2). There is no effect low dose regional analgesia on the duration of obstetric labor, nor the rate of instrumental births or caesarean section (NP1). Systematic use of oxytocin due to epidural analgesia is neither useful nor recommended (AE). Regional analgesia has no side effect on the fetus or newborn (NP1). If regional analgesia is contraindicated or during the waiting time, alternatives analgesic drugs (entonox, nalbuphine and tramadol or pudendal block) can be used but their analgesic efficiency remains mediocre to moderate and they are associated with adverse maternal and especially neonatal side effects (NP2). Remifentanil, ketamine and volatile anesthetics are excluded from these recommendations.

CONCLUSION

The present guidelines were established to update wellbeing of normal parturient during normal labor: hydration is recommended and low dose patient-controlled regional (epidural and spinal) analgesia is the most effective and safest analgesic method.

Female mice exposed to low doses of dioxin during pregnancy and lactation have increased susceptibility to diet-induced obesity and diabetes

Objective

Exposure to persistent organic pollutants is consistently associated with increased diabetes risk in humans. We investigated the short- and long-term impact of transient low-dose dioxin (2,3,7,8-tetrachlorodibenzo-p-dioxin, TCDD) exposure during pregnancy and lactation on glucose homeostasis and beta cell function in female mice, including their response to a metabolic stressor later in life.

Methods

Female mice were injected with either corn oil (CO; vehicle control) or 20 ng/kg/d TCDD 2x/week throughout mating, pregnancy and lactation, and then tracked for 6–10 weeks after chemical exposure stopped. A subset of CO- and TCDD-exposed dams was then transferred to a 45% high-fat diet (HFD) or remained on a standard chow diet for an additional 11 weeks to assess the long-term effects of TCDD on adaptability to a metabolic stressor. To summarize, female mice were transiently exposed to TCDD and then subsequently tracked beyond when TCDD had been excreted to identify lasting metabolic effects of TCDD exposure.

Results

TCDD-exposed dams were hypoglycemic at birth but otherwise had normal glucose homeostasis during and post-TCDD exposure. However, TCDD-exposed dams on a chow diet were modestly heavier than controls starting 5 weeks after the last TCDD injection, and their weight gain accelerated after transitioning to a HFD. TCDD-exposed dams also had an accelerated onset of hyperglycemia, impaired glucose-induced plasma insulin levels, reduced islet size, increased MAFA^-ve beta cells, and increased proinsulin accumulation following HFD feeding compared to controls. Overall, our study demonstrates that low-dose TCDD exposure during pregnancy has minimal effects on metabolism during the period of active exposure, but has detrimental long-term effects on metabolic adaptability to HFD feeding.

Conclusions

Our study suggests that transient low-dose TCDD exposure in female mice impairs metabolic adaptability to HFD feeding, demonstrating that dioxin exposure may be a contributing factor to obesity and diabetes pathogenesis in females.

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Female mice exposed to TCDD during pregnancy are hypoglycemic at birth.

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TCDD exposure promotes weight gain long after exposure ceases.

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TCDD-exposed dams fed a high-fat diet have accelerated onset of glucose intolerance.

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TCDDHFD dams have defects in islet morphology and beta cell function.

Can maternal treatment with metformin during gestation and lactation cause metabolic and cardiovascular disorders in rat offspring?

Objective: The aim was to evaluate if maternal treatment with metformin (MET) during pregnancy and lactation could be safe for metabolic and cardiovascular parameters of adult male and female offspring.Materials and methods: Wistar female rats were treated with MET (293 mg/kg/d) or tap water, by gavage during gestation (METG or CTRG) or gestation and lactation (METGL or CTRGL).Results: At 75 days of life, male and female MET offspring presented similar blood pressure when compared with their CTR. The heart rate of female METGL was higher than in the CTRGL. The insulin sensitivity, basal glycaemia, body weight, Lee index of obesity, plasmatic concentration of triglycerides, total cholesterol and fat acid of male and female MET were similar to CTR groups. Lower fat pad deposition was observed in female METG and METGL.Conclusion: MET exposure during gestational and lactation does not program cardiovascular and metabolic alterations in adult offspring life.

Characterization of visceral and subcutaneous adipose tissue transcriptome in pregnant women with and without spontaneous labor at term: implication of alternative splicing in the metabolic adaptations of adipose tissue to parturition

OBJECTIVE

The aim of this study was to determine gene expression and splicing changes associated with parturition and regions (visceral vs. subcutaneous) of the adipose tissue of pregnant women.

STUDY DESIGN

The transcriptome of visceral and abdominal subcutaneous adipose tissue from pregnant women at term with (n=15) and without (n=25) spontaneous labor was profiled with the Affymetrix GeneChip Human Exon 1.0 ST array. Overall gene expression changes and the differential exon usage rate were compared between patient groups (unpaired analyses) and adipose tissue regions (paired analyses). Selected genes were tested by quantitative reverse transcription-polymerase chain reaction.

RESULTS

Four hundred and eighty-two genes were differentially expressed between visceral and subcutaneous fat of pregnant women with spontaneous labor at term (q-value <0.1; fold change >1.5). Biological processes enriched in this comparison included tissue and vasculature development as well as inflammatory and metabolic pathways. Differential splicing was found for 42 genes [q-value <0.1; differences in Finding Isoforms using Robust Multichip Analysis scores >2] between adipose tissue regions of women not in labor. Differential exon usage associated with parturition was found for three genes (LIMS1, HSPA5, and GSTK1) in subcutaneous tissues.

CONCLUSION

We show for the first time evidence of implication of mRNA splicing and processing machinery in the subcutaneous adipose tissue of women in labor compared to those without labor.

Effects of labor on placental fatty acid β oxidation

OBJECTIVE

To measure the effect labor exerts on fatty acid (FA) oxidation in term human placentas, and to compare enzymes expression and activity between placenta and liver.

METHODS

Placental samples were collected: (a) scheduled non-labored cesarean section and (b) normal vaginal delivery at or beyond 37 weeks. Long and medium-chain FA oxidation were measured using (3)H-labeled FA, ATP concentration was measured via commercial kit. Activity and expression levels of 11 FA enzymes were measured and results compared to both human and mouse liver.

RESULTS

Placentas undergoing labor had significantly decreased palmitate oxidation and ATP levels. Octanoic acid oxidation was 10-fold higher than palmitic acid oxidation. No difference in expression or activity level was detected between the groups.

CONCLUSION

Term human placentas express all the enzymes required to oxidize FA, at a rate 20-fold lower than liver. FA Oxidation is not likely an important placental energy source during labor. Further work is needed to determine the functionality of this pathway in placenta.

Evidence for differential regulation of the adipokine visfatin in the maternal and fetal compartments in normal spontaneous labor at term

OBJECTIVE

Visfatin, a novel adipokine with metabolic and immunoregulatory properties, has been implicated in the regulation of fetal growth, as well as in preterm labor. A gap in knowledge is whether spontaneous labor at term is associated with changes in the maternal and fetal concentrations of visfatin. The aim of this study was to determine if the presence of labor at term is associated with alterations in maternal and neonatal plasma visfatin concentrations.

STUDY DESIGN

This cross-sectional study included 50 normal pregnant women at term and their appropriate-for-gestational age (AGA) neonates in the following groups: 1) 25 mother-neonate pairs delivered by elective cesarean section without spontaneous labor, and 2) 25 mother-neonate pairs who delivered vaginally following spontaneous labor. Maternal plasma and cord blood visfatin concentrations were determined by ELISA. Non-parametric statistics were used for analyses.

RESULTS

1) The median visfatin concentration was higher in umbilical cord plasma of neonates born following a spontaneous labor at term than that of those who were born by an elective cesarean section (P=0.02); 2) in contrast, the median maternal plasma visfatin concentration did not differ significantly between patients with and without labor (P=0.44); and 3) there was a significant correlation between umbilical cord plasma concentration of visfatin and both maternal visfatin concentration (r=0.54, P=0.005) and gestational age (GA) at delivery (r=0.58; P=0.002) only in the absence of labor.

CONCLUSION

Term labor is associated with increased fetal, but not maternal, circulating visfatin concentrations. Previous reports indicate that preterm labor leading to preterm delivery is characterized by an increase in maternal plasma concentrations of visfatin. The observations reported herein support the view that there are fundamental differences in the endocrine and metabolic adaptations in normal labor at term and preterm labor.

Intrapartum maternal glucose infusion and fetal acid-base status

OBJECTIVE

To compare the effects of an intrapartum infusion of a lactated Ringer solution or a glucose-boosted saline solution on the acid-base status of umbilical arterial blood.

METHOD

In a prospective clinical trial 178 women in labor were randomized to receive intravenously either a lactated Ringer solution or a saline solution boosted with 5% glucose. Umbilical arterial blood was then assessed for acid-base status.

RESULTS

There were significant differences between the lactated Ringer group and the glucose group in umbilical artery pH values (7.25+/-0.07 vs. 7.28+/-0.06; P=0.008), pCO2 values (44.8+/-5.6 mm Hg vs. 41.6+/-4.1 mm Hg; P=0.001), and base excess (-7.3+/-2.1 mEq/L vs. -6.6+/-1.8 mEq/L; P=0.02).

CONCLUSION

Intrapartum intravenous fluid containing a 5% glucose solution reduces umbilical cord acidemia and hypercarbia.

Apports alimentaires per os durant le travail obstétrical : éléments objectifs et subjectifs

Fasting during labour is questioned in France despite the historical recommendations by Curtis Mendelson. Solid food diet increases maternal nausea and vomiting of non digested food associated with a theoretical risk of severe aspiration syndrome. Clear fluids may improve the comfort of some parturients but it remains uncertain whether or not the obstetric consequences (i.e. duration of labour, Caesarean section rate) of carbohydrate supplementation are beneficial.