Role of leptin in pregnancy: Consequences of maternal obesity

Maternal obesity modulates sexually dimorphic epigenetic regulation and expression of leptin receptor in offspring hippocampus

Maternal obesity during pregnancy is associated with a greater risk for obesity and neurodevelopmental deficits in offspring. This developmental programming of disease is proposed to involve neuroendocrine, inflammatory, and epigenetic factors during gestation that disrupt normal fetal brain development. The hormones leptin and insulin are each intrinsically linked to metabolism, inflammation, and neurodevelopment, which led us to hypothesise that maternal obesity may disrupt leptin or insulin receptor signalling in the developing brain of offspring. Using a C57BL/6 mouse model of high fat diet-induced maternal obesity (mHFD), we performed qPCR to examine leptin receptor (Lepr) and insulin receptor (Insr) gene expression in gestational day (GD) 17.5 fetal brain. We found a significant effect of maternal diet and offspring sex on Lepr regulation in the developing hippocampus, with increased Lepr expression in female mHFD offspring (p < 0.05) compared to controls. Maternal diet did not alter hippocampal Insr in the fetal brain, or Lepr or Insr in prefrontal cortex, amygdala, or hypothalamus of female or male offspring. Chromatin immunoprecipitation revealed decreased binding of histones possessing the repressive histone mark H3K9me3 at the Lepr promoter (p < 0.05) in hippocampus of female mHFD offspring compared to controls, but not in males. Sex-specific deregulation of Lepr could be reproduced in vitro by exposing female hippocampal neurons to the obesity related proinflammatory cytokine IL-6, but not IL-17a or IFNG. Our findings indicate that the obesity-related proinflammatory cytokine IL-6 during pregnancy leads to sexually dimorphic changes in the modifications of histones binding at the Lepr gene promoter, and concomitant changes to Lepr transcription in the developing hippocampus. This suggests that exposure of the fetus to metabolic inflammatory molecules can impact epigenetic regulation of gene expression in the developing hippocampus.

Placental function in maternal obesity

Maternal obesity is associated with pregnancy complications and increases the risk for the infant to develop obesity, diabetes and cardiovascular disease later in life. However, the mechanisms linking the maternal obesogenic environment to adverse short- and long-term outcomes remain poorly understood. As compared with pregnant women with normal BMI, women entering pregnancy obese have more pronounced insulin resistance, higher circulating plasma insulin, leptin, IGF-1, lipids and possibly proinflammatory cytokines and lower plasma adiponectin. Importantly, the changes in maternal levels of nutrients, growth factors and hormones in maternal obesity modulate placental function. For example, high insulin, leptin, IGF-1 and low adiponectin in obese pregnant women activate mTOR signaling in the placenta, promoting protein synthesis, mitochondrial function and nutrient transport. These changes are believed to increase fetal nutrient supply and contribute to fetal overgrowth and/or adiposity in offspring, which increases the risk to develop disease later in life. However, the majority of obese women give birth to normal weight infants and these pregnancies are also associated with activation of inflammatory signaling pathways, oxidative stress, decreased oxidative phosphorylation and lipid accumulation in the placenta. Recent bioinformatics approaches have expanded our understanding of how maternal obesity affects the placenta; however, the link between changes in placental function and adverse outcomes in obese women giving birth to normal sized infants is unclear. Interventions that specifically target placental function, such as activation of placental adiponectin receptors, may prevent the transmission of metabolic disease from obese women to the next generation.

Second Trimester Maternal Leptin Levels Are Associated with Body Mass Index and Gestational Weight Gain but not Birth Weight of the Infant

INTRODUCTION

Obesity is increasing among the pregnant population. Leptin has an important role in the regulation of energy balance and hunger. The aim of this study was to investigate the association between maternal leptin levels with maternal obesity, gestational weight gain (GWG), single nucleotide polymorphisms (SNPs) within the leptin gene, and the age-adjusted birth weight of the child.

MATERIAL AND METHODS

Maternal leptin levels (n = 740) and SNPs (n = 504) were analyzed in blood samples taken within the Uppsala Biobank of Pregnant women at pregnancy weeks 16-19.

RESULTS

Maternal leptin levels differed significantly between body mass index (BMI) groups. Normal weight women had the lowest median leptin levels and levels increased with each BMI group. Leptin SNP genotype was not associated with leptin levels or BMI. There was also no association between maternal leptin levels and age-adjusted birth weight of the child except for a negative association between leptin levels and birth weight in the morbid obese group.

DISCUSSION/CONCLUSION

Maternal BMI was identified as the best positive explanatory factor for maternal leptin levels. Leptin was a strong positive explanatory factor for GWG. Birth weight of children of uncomplicated pregnancies was, however, dependent on maternal height, BMI, GWG, and parity but not leptin levels, except for in morbid obese women where a negative association between maternal leptin levels and birth weight was found. We speculate that this indicates altered placental function, not manifested in pregnancy complication. We conclude that maternal leptin levels do not affect the birth weight of the child more than BMI, GWG, and parity.

Maternal Obesity Modulates Expression of Satb2 in Hypothalamic VMN of Female Offspring

Maternal obesity during pregnancy is associated with a greater risk of poor health outcomes in offspring, including obesity, metabolic disorders, and anxiety, however the incidence of these diseases differs for males and females. Similarly, animal models of maternal obesity have reported sex differences in offspring, for both metabolic outcomes and anxiety-like behaviors. The ventromedial nucleus of the hypothalamus (VMN) is a brain region known to be involved in the regulation of both metabolism and anxiety, and is well documented to be sexually dimorphic. As the VMN is largely composed of glutamatergic neurons, which are important for its functions in modulating metabolism and anxiety, we hypothesized that maternal obesity may alter the number of glutamatergic neurons in the offspring VMN. We used a mouse model of a maternal high-fat diet (mHFD), to examine mRNA expression of the glutamatergic neuronal marker Satb2 in the mediobasal hypothalamus of control and mHFD offspring at GD17.5. We found sex differences in Satb2 expression, with mHFD-induced upregulation of Satb2 mRNA in the mediobasal hypothalamus of female offspring, compared to controls, but not males. Using immunohistochemistry, we found an increase in the number of SATB2-positive cells in female mHFD offspring VMN, compared to controls, which was localized to the rostral region of the nucleus. These data provide evidence that maternal nutrition during gestation alters the developing VMN, possibly increasing its glutamatergic drive of offspring in a sex-specific manner, which may contribute to sexual dimorphism in offspring health outcomes later in life.

Placental Lactogen as a Marker of Maternal Obesity, Diabetes, and Fetal Growth Abnormalities: Current Knowledge and Clinical Perspectives

Placental lactogen (PL) is a peptide hormone secreted throughout pregnancy by both animal and human specialized endocrine cells. PL plays an important role in the regulation of insulin secretion in pancreatic β-cells, stimulating their proliferation and promoting the expression of anti-apoptotic proteins. Cases of pregnancy affected by metabolic conditions, including obesity and diabetes, are related to alterations in the PL secretion pattern. Whereas obesity is most often associated with lower PL serum concentrations, diabetes results in increased PL blood levels. Disruptions in PL secretion are thought to be associated with an increased prevalence of gestational complications, such as placental dysfunction, diabetic retinopathy, and abnormalities in fetal growth. PL is believed to be positively correlated with birth weight. The impaired regulation of PL secretion could contribute to an increased incidence of both growth retardation and fetal macrosomia. Moreover, the dysregulation of PL production during the intrauterine period could affect the metabolic status in adulthood. PL concentration measurement could be useful in the prediction of fetal macrosomia in women with normal oral glucose tolerance test (OGTT) results or in evaluating the risk of fetal growth restriction, but its application in standard clinical practice seems to be limited in the era of ultrasonography.

Associations of maternal diet and placenta leptin methylation

BACKGROUND

Maternal diet is an important factor in prenatal development that also has implications for disease risk later in life. The adipokine leptin is a key regulator of energy homeostasis and may be involved in the association between maternal nutrition, maternal obesity, and infant outcomes. DNA methylation of placenta genes may occur in response to exposures and may program subsequent infant development. This study examined maternal diet, placenta leptin gene DNA methylation, and neonatal growth in a sample of healthy neonates and their mothers.

METHODS

Mothers and their healthy neonates (N = 135) were recruited within 1-2 days following delivery at Women and Infants Hospital in Providence, RI. A structured interview was conducted to assess maternal dietary intake. Maternal pre-pregnancy weight, weight gain during pregnancy, maternal health, medications, and vitamin use were obtained from medical records. Bisulfite pyrosequencing was used to measure methylation of CpG sites in the promoter region of the placenta leptin gene and determine genotype of the leptin single nucleotide polymorphism (SNP) rs2167270, which is known to influence leptin methylation. Bivariate analyses and linear regression models were used to evaluate associations of demographics, diet, and mean leptin methylation.

RESULTS

Genotype was a significant predictor of placenta leptin DNA methylation (p < .01), and after controlling for this and other relevant maternal and infant covariates, lower levels of leptin methylation were significantly associated with greater intake of carbohydrates (p < .05), in particular added sugars (p < .05) and white/refined carbohydrates (p < .05). Total caloric intake was also associated with placenta leptin methylation (p < .05), however after controlling for relevant covariates, significance diminished to trend-level. There were no significant associations of placenta leptin methylation and intake of protein (p > .05) or fat (p > .05).

CONCLUSION

These findings underline the importance of intake of carbohydrate consumption for methylation of the placenta leptin gene. Because methylation reduces gene transcription, lower methylation may indicate a placenta response to high caloric intake and carbohydrate food that would result in higher levels of this hormone during fetal development. Further investigation of the developmental ramifications of epigenetic changes to placenta leptin methylation should be pursued.

Changes in pregnancy-related serum biomarkers early in gestation are associated with later development of preeclampsia

Background

Placental protein expression plays a crucial role during pregnancy. We hypothesized that: (1) circulating levels of pregnancy-associated, placenta-related proteins throughout gestation reflect the temporal progression of the uncomplicated, full-term pregnancy, and can effectively estimate gestational ages (GAs); and (2) preeclampsia (PE) is associated with disruptions in these protein levels early in gestation; and can identify impending PE. We also compared gestational profiles of proteins in the human and mouse, using pregnant heme oxygenase-1 (HO-1) heterozygote (Het) mice, a mouse model reflecting PE-like symptoms.

Methods

Serum levels of placenta-related proteins–leptin (LEP), chorionic somatomammotropin hormone like 1 (CSHL1), elabela (ELA), activin A, soluble fms-like tyrosine kinase 1 (sFlt-1), and placental growth factor (PlGF)–were quantified by ELISA in blood serially collected throughout human pregnancies (20 normal subjects with 66 samples, and 20 subjects who developed PE with 61 samples). Multivariate analysis was performed to estimate the GA in normal pregnancy. Mean-squared errors of GA estimations were used to identify impending PE. The human protein profiles were then compared with those in the pregnant HO-1 Het mice.

Results

An elastic net-based gestational dating model was developed (R² = 0.76) and validated (R² = 0.61) using serum levels of the 6 proteins measured at various GAs from women with normal uncomplicated pregnancies. In women who developed PE, the model was not (R² = -0.17) associated with GA. Deviations from the model estimations were observed in women who developed PE (P = 0.01). The model developed with 5 proteins (ELA excluded) performed similarly from sera from normal human (R² = 0.68) and WT mouse (R² = 0.85) pregnancies. Disruptions of this model were observed in both human PE-associated (R² = 0.27) and mouse HO-1 Het (R² = 0.30) pregnancies. LEP outperformed sFlt-1 and PlGF in differentiating impending PE at early human and late mouse GAs.

Conclusions

Serum placenta-related protein profiles are temporally regulated throughout normal pregnancies and significantly disrupted in women who develop PE. LEP changes earlier than the well-established biomarkers (sFlt-1 and PlGF). There may be evidence of a causative action of HO-1 deficiency in LEP upregulation in a PE-like murine model.

Early-life programming of adipose tissue

Worldwide obesity is increasing at an alarming rate in children and adolescents, with the consequent emergence of co-morbidities. Moreover, the maternal environment during pregnancy plays an important role in obesity, contributing to transgenerational transmission of the same and metabolic dysfunction. White adipose tissue represents a prime target of metabolic programming induced by maternal milieu. In this article, we review adipose tissue physiology and development, as well as maternal influences during the perinatal period that may lead to obesity in early postnatal life and adulthood. First, we describe the adipose tissue cell composition, distribution and hormonal action, together with the evidence of hormonal factors participating in fetal/postnatal programming. Subsequently, we describe the critical periods of adipose tissue development and the relationship of gestational and early postnatal life with healthy fetal adipose tissue expansion. Furthermore, we discuss the evidence showing that adipose tissue is an important target for nutritional, hormonal and epigenetic signals to modulate fetal growth. Finally, we describe nutritional, hormonal, epigenetic and microbiome changes observed in maternal obesity, and whether their disruption alters fetal growth and adiposity. The presented evidence supports the developmental origins of health and disease concept, which proposes that the homeostatic system is affected during gestational and postnatal development, impeding the ability to regulate body weight after birth, thereby resulting in adult obesity. Consequently, we anticipate that promoting a healthy early-life programming of adipose tissue and increasing the knowledge of the mechanisms by which maternal factors affect the health of future generations may offer novel strategies for explaining and addressing worldwide health problems such as obesity.

The association of maternal obesity and race with serum adipokines in pregnancy and postpartum: Implications for gestational weight gain and infant birth weight

Adiponectin and leptin are hormones known to play roles in maternal metabolism during pregnancy. Levels of these hormones have been demonstrated to vary based on adiposity and race. However, there is a lack of data concerning the relationship between race and the change of adiponectin and leptin throughout pregnancy. The purpose of this study was to examine serum levels of adiponectin, leptin, and leptin-to-adiponectin ratio (LAR) throughout pregnancy and to assess their association with gestational weight gain (GWG) and infant birth weight while considering the effects of race and pre-pregnancy body mass index (BMI). Serum levels of adiponectin, leptin, gestational weight gain, and infant birth weight were measured in 80 pregnant women at early (12.4 ​± ​1.3 weeks gestation), mid (20.6 ​± ​1.3 weeks gestation), late pregnancy (29.2 ​± ​1.4 weeks gestation), and 7-11 weeks postpartum (8.8 ​± ​0.8 weeks). In women overall, serum adiponectin decreased across pregnancy and increased at postpartum (p ​= ​0.17.) At each prenatal timepoint, both black race and obesity were associated with lower adiponectin (ps ​< ​0.05). In women overall, serum leptin increased across pregnancy, and declined at postpartum. At every assessment, a stepwise increase in leptin was observed in relation to BMI class. Black women with obesity had markedly higher LAR in mid- and late pregnancy and postpartum than all other groups (p ​< ​0.05). Serum leptin during pregnancy was significantly associated with total GWG in both black and white women (ps ​< ​0.005). Neither adiponectin, leptin, nor LAR were associated with infant birth weight. Race and BMI both have significant effects on serum adiponectin, leptin, and LAR levels in pregnancy and postpartum. Notably, the combined effects of race and BMI result in markedly higher LAR among black women with obesity. Implications for racial disparities in metabolic syndrome and postpartum weight retention remain to be explicated.

IL-10-Producing Potential Treg Precursor in Placenta

The maternal immune system needs to be tolerant of allogeneic fetal tissue for reproductive success. The regulatory immune cell network plays an essential role in maintaining maternal tolerance to the fetus. We herein demonstrate in a green fluorescent protein (GFP)/IL-10 reporter mouse system that unique IL-10-expressing cells exist presumably in chorionic villi within the placenta. Flow cytometric analysis revealed that these IL-10- expressing cells exhibit a unique CD19 negative, CD3 negative, and B220 positive phenotype. Interestingly, these cells were enriched during in vitro culture, but well-known stimuli for T cells and B cells failed to enhance their growth, suggesting that the CD19^- CD3^- B220⁺ cells were self renewing. Unexpectedly, in an adoptive cell trans fer experiment, IL-10 production was detected in Sca-1⁺ CD4⁺ CD25⁺ regulatory T cells (Treg). To our knowledge, this is the first report to identify IL-10-producing CD19^- CD3^- B220⁺ cells in the fetus. These cells may rep resent a potential progenitor of Sca-1⁺ Treg or pluripotent precursor cells for immune tolerance.

Maternal serum and cord blood leptin concentrations at delivery

Introduction

Studies have demonstrated leptin involvement in the physiology and pathophysiology of pregnancy and suggest that leptin may be a prognostic marker for some complications of pregnancy although the association remains unclear. To date no studies have reported leptin reference intervals established in normal pregnancy, which could be used for interpreting the differences in leptin levels found in normal and pathological pregnancies.

Objective

To determine leptin concentrations at delivery, in maternal serum in normal pregnancy and in cord blood and to establish reference intervals for leptin.

Material and methods

The study was performed in 194 pregnant women without any comorbid health conditions. Leptin concentrations in maternal serum and in cord blood were measured by ELISA and subsequently analyzed by gestational age (weeks), maternal Body Mass Index (BMI), mode of delivery and infant gender and birth weight. For comparative analyses of normally distributed variables, parametric tests such as the Student–t were used to test the assumption of homogeneity or non-homogeneity of variance and a One-Way ANOVA when more than two groups were compared. The Pearson correlation coefficient was calculated to assess the correlation between normally distributed variables (p<0.05). The reference intervals for leptin were obtained by referring to the central 95% of laboratory test values.

Results

In normal pregnant women, the mean serum leptin concentration at delivery was 37.17 ± 28.07 ng/mL and the established reference interval was 33.19–41.14 ng/mL. The mean leptin concentration in cord blood was 14.78 ± 15.97 ng/mL and the established reference interval was 12.32–17.67 ng/mL. There was a statistically significant positive correlation between maternal serum and cord blood leptin concentrations (r = 0.37; p = 0.00). Mean leptin concentrations in cord blood increased with gestational age (p = 0.00). No statistically significant differences in maternal serum and cord blood leptin concentrations were found in regard to mode of delivery and neonatal gender. A statistically significant correlation was found between maternal serum leptin and third-trimester BMI (r = 0.22; p = 0.00), but there was no association between maternal BMI and cord blood leptin concentration. There was a statistically significant positive correlation between cord blood leptin concentration and birth weight (r = 0.23; p = 0.00).

Conclusions

Reference intervals for leptin in maternal serum and in cord blood established in normal pregnancy could be used in clinical practice for interpreting the differences in leptin concentrations found in normal pregnancy and in complications of pregnancy. The results indicate a strong association between maternal serum leptin levels and obesity and between cord blood leptin levels and birth weight.

Postnatal administration of leptin antagonist mitigates susceptibility to obesity under high-fat diet in male αMUPA mice

Perturbations in postnatal leptin signaling have been associated with altered susceptibility to diet-induced obesity (DIO) under high-fat-diet (HFD), albeit with contradicting evidence. Previous studies have shown that alpha murine urokinase-type plasminogen activator (αMUPA) mice have a higher and longer postnatal leptin surge compared with their wild types (WTs) as well as lower body weight and food intake under regular diet (RD). Here we explored αMUPA's propensity for DIO and the effect of attenuating postnatal leptin signaling with leptin antagonist (LA) on energy homeostasis under both RD and HFD. Four-day-old αMUPA pups were treated on alternate days until postnatal day 18 with either vehicle or LA (10 or 20 mg·day^-1·kg^-1) and weaned into RD or HFD. Compared with RD-fed αMUPA males, HFD-fed αMUPA males showed higher energy intake, even when corrected for body weight difference, and became hyperinsulinemic and obese. Additionally, HFD-fed αMUPA males gained body weight at a higher rate than their WTs mainly because of strain differences in energy expenditure. LA administration did not affect strain differences under RD but attenuated αMUPA's hyperinsulinemia and DIO under HFD, most likely by mediating energy expenditure. Together with our previous findings, these results suggest that αMUPA's leptin surge underlies its higher susceptibility to obesity under HFD, highlighting the role of leptin-related developmental processes in inducing obesity in a postweaning obesogenic environment, at least in αMUPA males. This study therefore supports the use of αMUPA mice for elucidating developmental mechanisms of obesity and the efficacy of early-life manipulations via leptin surge axis in attenuating DIO.

Leptin as a breast milk component for the prevention of obesity

Leptin ingested as a component of breast milk is increasingly recognized to play a role in the postnatal programming of a healthy phenotype in adulthood. Besides its primary function in controlling body weight, leptin may be an essential nutrient required during lactation to ensure that the system controlling fat accumulation and body composition is well organized from the early stages of development. This review delves into the following topics: (1) the imprinted protective function of adequate leptin intake during lactation in future metabolic health; (2) the consequences of a lack of leptin intake or of alterations in leptin levels; and (3) the mechanisms described for the effects of leptin on postnatal programming. Furthermore, it highlights the importance of breastfeeding and the need to establish optimal or reference intake values for leptin during lactation to design patterns of personalized nutrition from early childhood.

Longitudinal changes in adipokines and free leptin index during and after pregnancy in women with obesity

OBJECTIVE

Detailed data on adipokines and body composition during and after pregnancy in women of different BMI categories are lacking. Furthermore, adipokine regulation during pregnancy and the factors contributing to gestational insulin resistance are not completely understood. The objective was to longitudinally determine adipokine levels, body composition, and insulin sensitivity during and after pregnancy in women of healthy weight (HW) and with obesity (OB), and identify factors associated with insulin resistance.

DESIGN

Women (30 HW, 19 OB) underwent blood sampling and body composition examination, by air-displacement plethysmography, longitudinally during pregnancy (trimesters 1, 2, 3) and after pregnancy (6, 12, 18 months postpartum). Serum leptin, soluble leptin receptor (sOB-R), and adiponectin levels were measured and free leptin index (FLI) and homeostatic model assessment of insulin resistance (HOMA-IR) determined.

RESULTS

Fat mass and leptin increased during pregnancy in the HW (p < 0.01) but not in the OB group. sOB-R increased during pregnancy in both groups (p < 0.001). Thus, FLI was unchanged in HW throughout pregnancy but reduced in OB (p = 0.001), although consistently higher in OB. Adiponectin decreased in both groups during pregnancy (p < 0.001 for HW, p = 0.01 for OB). After pregnancy, adiponectin increased in both groups, but more markedly in OB where it reached trimester 1 levels. Multivariable regression identified FLI as the variable most strongly associated with HOMA-IR in all trimesters, but not after pregnancy.

CONCLUSIONS

Leptin, sOB-R, adiponectin, and FLI undergo marked changes during and after pregnancy with differences in women of different BMI. We suggest that leptin activity is regulated by its soluble receptor and that this is an important factor for optimizing fat mass and insulin sensitivity during pregnancy.

The Effects of Leptin on Glial Cells in Neurological Diseases

It is known that various endocrine modulators, including leptin and ghrelin, have neuroprotective roles in neurological diseases. Leptin is a hormone produced by adipocytes and was originally identified as a gene related to obesity in mice. The leptin receptors in the hypothalamus are the main target for the homeostatic regulation of body weight. Recent studies have demonstrated that leptin receptors are also expressed in other regions of the central nervous system (CNS), such as the hippocampus, cerebral cortex, and spinal cord. Accordingly, these studies identified the involvement of leptin in the regulation of neuronal survival and neural development. Furthermore, leptin has been shown to have neuroprotective functions in animal models of neurological diseases and demyelination. These observations also suggest that dysregulation of leptin signaling may be involved in the association between neurodegeneration and obesity. In this review, we summarize novel functions of leptin in animal models of neurodegenerative diseases. Specifically, we focus on the emerging evidence for the role of leptin in non-neuronal cells in the CNS, including astrocytes, microglia, and oligodendrocytes. Understanding leptin-mediated neuroprotective signals and molecular mechanisms underlying remyelination will be helpful to establish therapeutic strategies against neurological diseases.

Dyslipidemia and the role of adipose tissue in early pregnancy in the BPH/5 mouse model for preeclampsia

The hypertensive pregnancy disorder preeclampsia (PE) is a leading cause of fetal and maternal morbidity/mortality. Obesity increases the risk to develop PE, presumably via the release of inflammatory mediators from the adipose tissue, but the exact etiology remains largely unknown. Using obese PE-like blood pressure high subline 5 (BPH/5) and lean gestational age-matched C57Bl6 mice, we aimed to obtain insight into differential reproductive white adipose tissue (rWAT) gene expression, circulating lipids and inflammation at the maternal-fetal interface during early pregnancy. In addition, we investigated the effect of 7 days 25% calorie restriction (CR) in early pregnancy on gene expression in rWAT and implantation sites. Compared with C57Bl6, female BPH/5 are dyslipidemic before pregnancy and show an amplification of rWAT mass, circulating cholesterol, free fatty acids, and triacylglycerol levels throughout pregnancy. RNA sequencing showed that pregnant BPH/5 mice have elevated gene enrichment in pathways related to inflammation and cholesterol biosynthesis at embryonic day (e) 7.5. Expression of cholesterol-related HMGCS1, MVD, Cyp51a1, and DHCR was validated by quantitative reverse-transcription-polymerase chain reaction. CR during the first 7 days of pregnancy restored the relative mRNA expression of these genes to a level comparable to C57Bl6 pregnant females and reduced the expression of circulating leptin and proinflammatory prostaglandin synthase 2 in both rWAT and implantation sites in BPH/5 mice at e7.5. Our data suggest a possible role for rWAT in the dyslipidemic state and inflammatory uterine milieu that might underlie the pathogenesis of PE. Future studies should further address the physiological functioning of the adipose tissue in relation to PE-related pregnancy outcomes.

Genetic aspects of metabolic disorders in pregnant women with pathological weight gain

Polymorphism of the leptin receptor gene (LEPR) has been shown to be linked to obesity-related metabolic markers and phenotype. Therefore, we hypothesized that the Gln233Arg LEPR polymorphism is related to metabolic changes in pregnancy and the risk of excessive gestational weight gain (GWG). A total of 97 pregnant women with a singleton gestation were enrolled from April 2016 until December 2018. Genetic variants of LEPR were analyzed by real-time polymerase chain reaction, leptin by enzyme-linked immunosorbent assay, lipid profile, and carbohydrate status were assessed in the first, and third trimesters of pregnancy. The recommended GWG was diagnosed in 34.0%, insufficient in 19.6%, and excessive in 46.4% patients. Statistical analysis revealed that 20.6% patients were with AA genotype, 50.5% – AG genotype, and 28.9% – GG genotype. The frequency of GG-alleles carriers of the LEPR Gln233Arg gene in the group of excessive GWG patients was 3 times higher compared to recommended GWG patients. Thus, the inheritance of pathological G-homozygotes increases the risk of excessive weight gain by 7 times, compared to carriers of the AA genotype. LEPR GG polymorphism was significantly associated with high levels of triglycerides, total cholesterol, lipoprotein low and very low density, and leptin compared to homozygous А-carriers in the third trimester of pregnancy. In pregnant women with GG polymorphism, the glucose level, insulin level, and HOMO-IR index were significantly increased compared to women with AA genotype in late pregnancy. In the group with excessive GWG, the presence of GG-alleles of the LEPR gene was accompanied by a higher level of hyperleptinemia, compared to carriers of AA-genotype. Inheritance of pathological G-homozygotes was associated with hyperlipidemia, leptin resistance with high leptin serum levels, and increased insulin resistance, which was especially manifested in excessive GWG. In our opinion, excessive GWG can be seen as a marker of the mother's genotype and genetic predisposition to the development of metabolic diseases after delivery.

Skeletal muscle as a protagonist in the pregnancy metabolic syndrome

The pregnant woman normally shows clinical manifestations similar to a metabolic syndrome (MS), due to her metabolic and hemodynamic adaptations in order to share nutrients with the child. If those adjustments are surpassed, a kind of pregnancy MS (PregMS) could appear, characterized by excessive insulin resistance and vascular maladaptation. Skeletal muscle (SKM) must be a protagonist in the PregMS: SKM strength and mass have been associated inversely with MS incidence in non-pregnant patients, and in pregnant women muscular activity modulates metabolic and vascular adaptations that favor better outcomes. Of note, a sedentary lifestyle affects exactly in the other way. Those effects may be explained not only by the old paradigm of SKM being a great energy consumer and store, but because it is an endocrine organ whose chronic activity or deconditioning correspondingly releases myokines modulating insulin sensitivity and cardiovascular adaptation, by direct or indirect mechanisms not well understood. In this document, we present evidence to support the concept of a PregMS and hypothesize on the role of the SKM mass, fiber types composition and myokines in its pathophysiology. Also, we discuss some exercise interventions in pregnancy as a way to test our hypotheses.

Maternal obesity influences expression and DNA methylation of the adiponectin and leptin systems in human third-trimester placenta

BACKGROUND

It is well established that obesity is associated with dysregulation of the ratio between the two major adipokines leptin and adiponectin. Furthermore, it was recently reported that maternal obesity has a significant impact on placental development. Leptin and adiponectin are present at the fetal-maternal interface and are involved in the development of a functional placenta. However, less is known about leptin and adiponectin's involvement in the placental alterations described in obese women. Hence, the objective of the present study was to characterize the placental expression and DNA methylation of these two adipokine systems (ligands and receptors) in obese women.

RESULTS

Biopsies were collected from the fetal and maternal sides of third-trimester placenta in obese and non-obese (control) women. In both groups, leptin levels were higher on the fetal side than the maternal side, suggesting that this cytokine has a pivotal role in fetal growth. Secondly, maternal obesity (in the absence of gestational diabetes) was associated with (i) elevated DNA methylation of the leptin promoter on fetal side only, (ii) hypomethylation of the adiponectin promoter on the maternal side only, (iii) significantly low levels of leptin receptor protein (albeit in the absence of differences in mRNA levels and promoter DNA methylation), (iv) significantly low levels of adiponectin receptor 1 mRNA expression on the maternal side only, and (v) elevated DNA methylation of the adiponectin receptor 2 promoter on the maternal side only.

CONCLUSION

Our present results showed that maternal obesity is associated with the downregulation of both leptin/adiponectin systems in term placenta, and thus a loss of the beneficial effects of these two adipokines on placental development. Maternal obesity was also associated with epigenetic changes in leptin and adiponectin systems; this highlighted the molecular mechanisms involved in the placenta's adaptation to a harmful maternal environment.

Role of insulin, adenosine, and adipokine receptors in the foetoplacental vascular dysfunction in gestational diabetes mellitus

Gestational diabetes mellitus (GDM) is a disease of pregnancy associated with maternal and foetal hyperglycaemia and altered foetoplacental vascular function. Human foetoplacental microvascular and macrovascular endothelium from GDM pregnancy show increased maximal l-arginine transport capacity via the human cationic amino acid transporter 1 (hCAT-1) isoform and nitric oxide (NO) synthesis by the endothelial NO synthase (eNOS). These alterations are paralleled by lower maximal transport activity of the endogenous nucleoside adenosine via the human equilibrative nucleoside transporter 1 (hENT1) and activation of adenosine receptors. A causal relationship has been described for adenosine-activation of A_2A adenosine receptors, hCAT-1, and eNOS activity (i.e. the Adenosine/l-Arginine/Nitric Oxide, ALANO, signalling pathway). Insulin restores these alterations in GDM via activation of insulin receptor A (IR-A) form in the macrovascular but IR-A and IR-B forms in the microcirculation of the human placenta. Adipokines are secreted from adipocytes influencing the foetoplacental metabolic and vascular function. Various adipokines are dysregulated in GDM, with adiponectin and leptin playing major roles. Abnormal plasma concentration of these adipokines and the activation or their receptors are involved in the pathophysiology of GDM. However, involvement of adipokines, adenosine, and insulin receptors and membrane transporters in the aetiology of this disease of pregnancy is unknown. This review focuses on the pathophysiology of insulin and adenosine receptors and l-arginine and adenosine membranes transporters giving an overview of the key adipokines leptin and adiponectin in the foetoplacental vasculature in GDM. This article is part of a Special Issue entitled: Membrane Transporters and Receptors in Pregnancy Metabolic Complications edited by Luis Sobrevia.

Maternal β-Cell Adaptations in Pregnancy and Placental Signalling: Implications for Gestational Diabetes

Rates of gestational diabetes mellitus (GDM) are on the rise worldwide, and the number of pregnancies impacted by GDM and resulting complications are also increasing. Pregnancy is a period of unique metabolic plasticity, during which mild insulin resistance is a physiological adaptation to prioritize fetal growth. To compensate for this, the pancreatic β-cell utilizes a variety of adaptive mechanisms, including increasing mass, number and insulin-secretory capacity to maintain glucose homeostasis. When insufficient insulin production does not overcome insulin resistance, hyperglycemia can occur. Changes in the maternal system that occur in GDM such as lipotoxicity, inflammation and oxidative stress, as well as impairments in adipokine and placental signalling, are associated with impaired β-cell adaptation. Understanding these pathways, as well as mechanisms of β-cell dysfunction in pregnancy, can identify novel therapeutic targets beyond diet and lifestyle interventions, insulin and antihyperglycemic agents currently used for treating GDM.

Fetal and Infancy Growth Pattern, Cord and Early Childhood Plasma Leptin, and Development of Autism Spectrum Disorder in the Boston Birth Cohort

Leptin is a proinflammatory cytokine that plays an important role in energy homeostasis. Emerging evidence suggests that leptin levels are altered in children with autism spectrum disorder (ASD); however, this has not been studied prospectively. Rapid growth during infancy and early childhood has been implicated in ASD, but the evidence is inconsistent. As leptin is involved in growth and is a potential risk factor for ASD, we explored the associations between (a) cord, early childhood leptin and ASD; and (b) birth weight for gestational age, early childhood weight gain, and ASD. We also assessed the mediating role of leptin in the relationship between weight gain during infancy and ASD. This study was conducted in a sample of 822 subjects from the Boston Birth Cohort. ASD was defined from diagnostic codes in electronic medical records. Extremely rapid weight gain during infancy was associated with a greater ASD risk and this persisted after adjusting for potential confounders (aOR: 3.11; 95% CI: 1.37, 7.07). Similarly, children that had higher plasma leptin levels, prior to ASD diagnosis, had an increased ASD risk in both unadjusted and adjusted models (aOR: 7.87; 95% CI: 2.06, 30.04). Further, early childhood leptin indirectly mediated the relationship between rapid weight gain and ASD. No associations were found between birth weight for gestational age, cord leptin and risk of ASD. Our findings provide a basis to further explore whether the combination of early life growth pattern and a biomarker such as leptin can predict ASD earlier. Autism Res 2018, 11: 1416-1431. © 2018 International Society for Autism Research, Wiley Periodicals, Inc. LAY SUMMARY: Is early life growth and a biomarker leptin related to ASD risk? To answer this question, we followed 822 children from birth and found that those who gained weight very quickly in infancy, had higher leptin levels in early childhood, had a greater chance of later ASD diagnosis. More research is needed to see if infant's weight gain pattern along with a biomarker (such as leptin) can be used to identify children with ASD sooner.

Mode of infant feeding, eating behaviour and anthropometry in infants at 6-months of age born to obese women - a secondary analysis of the UPBEAT trial

BACKGROUND

Maternal obesity and rapid infant weight gain have been associated with increased risk of obesity in childhood. Breastfeeding is suggested to be protective against childhood obesity, but no previous study has addressed the potential benefit of breastfeeding as a preventive method of childhood obesity amongst obese women. The primary aim of this study was to assess the relationship between mode of feeding and body composition, growth and eating behaviours in 6-month-old infants of obese women who participated in UPBEAT; a multi-centre randomised controlled trial comparing a lifestyle intervention of diet and physical activity to standard care during pregnancy.

METHODS

Three hundred and fifty-three mother and infant pairs attended a 6-months postpartum follow-up visit, during which they completed the Baby-Eating Behaviour Questionnaire, a parent-reported psychometric measure of appetite traits. Measures of infant body composition were also undertaken. As there was no effect of the antenatal intervention on infant feeding and appetite the study was treated as a cohort. Using regression analyses, we examined relationships between: 1) mode of feeding and body composition and growth; 2) mode of feeding and eating behaviour and 3) eating behaviour and body composition.

RESULTS

Formula fed infants of obese women in comparison to those exclusively breastfed, demonstrated higher weight z-scores (mean difference 0.26; 95% confidence interval 0.01 to 0.52), higher rate of weight gain (0.04; 0.00 to 0.07) and greater catch-up growth (2.48; 1.31 to 4.71). There was also a lower enjoyment of food (p = 0.002) amongst formula fed infants, following adjustment for confounders. Independent of the mode of feeding, a measure of infant appetite was associated with sum of skinfold thicknesses (β 0.66; 95% CI 0.12 to 1.21), calculated body fat percentage (0.83; 0.15 to 1.52), weight z-scores (0.21; 0.06 to 0.36) and catch-up growth (odds ratio 1.98; 1.21 to 3.21).

CONCLUSIONS

In obese women, exclusive breastfeeding was protective against increasing weight z-scores and trajectories of weight gain in their 6-month old infants. Measures of general appetite in early infancy were associated with measures of adiposity, weight and catch up growth independent of cord blood leptin concentrations and mode of early feeding.

Serum adipokine levels and insulin resistance in the first trimester of pregnancy in adolescents and their relationship with neonatal weight

Introduction: The approach to the physiology of pregnancy based on adipokine behavior and the homeostasis-insulin resistance (HOMA-IR) model, along with their relationship to neonatal weight, has been poorly studied in adolescent pregnant women. Objective: To determine possible correlations between adipokines –leptin and adiponectin– and HOMA-IR in pregnant women aged 14 to 17 years, and first-trimester body mass index (BMI) and neonatal weight. Materials and methods: In the weeks 11 to 14 of gestation, the biochemical variables leptin, adiponectin, glycemia and insulin were measured and HOMA-IR was calculated. Maternal and neonatal anthropometric variables were obtained. Statistical analysis was performed with Pearson correlation and the p value. Results: We noticed a positive correlation of serum leptin levels with HOMA-IR in the first trimester of gestation (r=0.5, p≤0.000) and a negative correlation between adiponectin and HOMA-IR (r=-0.4; p=0.017), along with positive correlations between BMI and leptin, insulin and HOMA-IR (r=0.83 and p <0.000, r=0.56 and p≤0.000; r=0.54 and p≤0.000, respectively). In adolescent non-obese mothers with no history of dyslipidemia, there was a positive correlation between HOMA-IR and neonatal weight (r=0.43, p=0.012). Conclusions: Leptin and HOMA-IR showed a positive correlation, while adiponectin and HOMA-IR showed a negative correlation. Leptin and HOMA-IR were positively correlated with BMI. HOMA-IR correlated with the weight of neonates of non-obese adolescents without dyslipidemia.

The adipocyte hormone leptin sets the emergence of hippocampal inhibition in mice

Brain computations rely on a proper balance between excitation and inhibition which progressively emerges during postnatal development in rodent. γ-Aminobutyric acid (GABA) neurotransmission supports inhibition in the adult brain but excites immature rodent neurons. Alterations in the timing of the GABA switch contribute to neurological disorders, so unveiling the involved regulators may be a promising strategy for treatment. Here we show that the adipocyte hormone leptin sets the tempo for the emergence of GABAergic inhibition in the newborn rodent hippocampus. In the absence of leptin signaling, hippocampal neurons show an advanced emergence of GABAergic inhibition. Conversely, maternal obesity associated with hyperleptinemia delays the excitatory to inhibitory switch of GABA action in offspring. This study uncovers a developmental function of leptin that may be linked to the pathogenesis of neurological disorders and helps understanding how maternal environment can adversely impact offspring brain development.

Maternal plasma leptin levels in relation to the duration of the active phase of labor

INTRODUCTION

Obese women have increased leptin levels and longer duration of labor compared with normal-weight women. Leptin has an inhibitory effect on myometrial contractility in vitro. Our purpose was to examine whether maternal leptin levels in active labor were associated with the duration of the active phase of labor.

MATERIAL AND METHODS

This prospective cohort study included 914 women. Maternal blood samples were collected in active labor. The plasma-leptin concentration was obtained using a direct sandwich-based ELISA. Bivariate and multiple linear regression analyses were used to study the association between leptin levels and the duration of labor.

RESULTS

A 1 ng/mL increase in maternal plasma leptin was associated with a 0.015 hour increase in duration of labor (P < .007). This association was not statistically significant in the adjusted analyses nor when analyzing nulliparous and multiparous women separately. In women with spontaneous labor (n = 766) leptin levels were not associated with an increase in duration of labor in the adjusted analyses.

CONCLUSIONS

There was no significant association between leptin levels and duration of the active phase of labor. Leptin in vivo might display a similar dose-response effect on myometrial contractility as demonstrated in in vitro studies. Future studies need to explore the association between leptin levels and time in labor in obese women with high leptin levels to evaluate a possible dose-response effect.

Obesity and High-Fat Diet Induce Distinct Changes in Placental Gene Expression and Pregnancy Outcome

Obese women are at high risk of pregnancy complications, including preeclampsia, miscarriage, preterm birth, stillbirth, and neonatal death. In the current study, we aimed to determine the effects of obesity on pregnancy outcome and placental gene expression in preclinical mouse models of genetic and nutritional obesity. The leptin receptor (LepR) null-reactivatable (LepRloxTB), LepR-deficient (Leprdb/+), and high-fat diet (HFD)-fed mice were assessed for fertility, pregnancy outcome, placental morphology, and placental transcriptome using standard quantitative polymerase chain reaction (qPCR) and qPCR arrays. The restoration of fertility of LepRloxTB was performed by stereotaxic delivery of adeno-associated virus-Cre into the hypothalamic ventral premammillary nucleus. Fertile LepRloxTB females were morbidly obese, whereas the wild-type mice-fed HFD showed only a mild increase in body weight. Approximately 80% of the LepRloxTB females had embryo resorptions (∼40% of the embryos). In HFD mice, the number of resorptions was not different from controls fed a regular diet. Placentas of resorbed embryos from obese mice displayed necrosis and inflammatory infiltrate in the labyrinth and changes in the expression of genes associated with angiogenesis and inflammation (e.g., Vegfa, Hif1a, Nfkbia, Tlr3, Tlr4). In contrast, placentas from embryos of females on HFD showed changes in a different set of genes, mostly associated with cellular growth and response to stress (e.g., Plg, Ang, Igf1, Igfbp1, Fgf2, Tgfb2, Serpinf1). Sexual dimorphism in gene expression was only apparent in placentas from obese LepRloxTB mice. Our findings indicate that an obese environment and HFD have distinct effects on pregnancy outcome and the placental transcriptome.

Assessment of squalene eligibility in bettering some maternal and fetal disorders instigated by gamma irradiation of rats at mid gestation

PURPOSE

Squalene is an eminent vital part of the synthesis of steroid hormones in the body as well as the first specific intermediate in cholesterol biosynthesis that plays an essential role in normal embryogenesis. The present work was designed to test the maternal and embryonic response to the modulating capacity of squalene (0.4 ml/kg/d), when supplemented to rats from days 1 to 18 of pregnancy, against the damaging consequences induced by maternal subjection to 3 Gy gamma irradiation on day 10 post-conception.

MATERIALS AND METHODS

The experimental protocol comprised of four different pregnant groups, namely: (1) control, (2) squalene supplemented, (3) irradiated and (4) squalene supplemented + irradiated.

RESULTS

It has been detected that radiation has increased the maternal blood lactate dehydrogenase (as a marker of tissue injury), cholesterol, triglycerides, estradiol and progesterone and has also provoked the oxidative stress that has been demonstrated by the increased malondialdehyde (MDA) and the decreased glutathione (GSH) and superoxide dismutase (SOD). These maternal changes were associated with high embryonic lethality, growth retardation, severe developmental abnormalities and defective neural tube closure expressed by exencephaly. However, squalene treatment has significantly improved the radiation imposed maternal variations and reduced the embryonic mortality, although it has not been able to attenuate the embryonic neural tube defects.

CONCLUSIONS

It has been presumed that the maternal mid-gestational irradiation (day 10) has affected the fetal nervous system development with concomitant maternal oxidative stress, hyperlipidemia, and increased progesterone and estradiol levels. Squalene uptake has improved the maternal variations and reduced the embryonic mortality while could not stop or improve the embryonic neural tube defects imposed by radiation at this exact radiation timing.

Angiogenic factor screening in women with mild preeclampsia - New and significant proteins in plasma

INTRODUCTION

The aim of this study was to analyse a panel of 60 angiogenic factors (pro-angiogenic and antiangiogenic) in the plasma of women with mild preeclampsia.

MATERIALS AND METHODS

We recruited 21 women between 25 and 40 weeks gestation with diagnosed mild preeclampsia into the study group and 27 healthy women with uncomplicated pregnancies of corresponding gestational age to that of the study to the control group. We used a quantitative protein macroarray method that allowed for analysis of 60 angiogenic proteins per sample simultaneously.

RESULTS

We showed a statistically significant increase in the concentration of 8 proteins, interferon gamma (IFN-γ), interleukin 6 (IL-6), leukaemia inhibitory factor (LIF), heparin-binding EGF-like growth factor (HB-EGF), hepatocyte growth factor (HGF), C-X-C motif chemokine 10 (IP-10), leptin and platelet-derived growth factor BB (PDGF-BB), as well as a significant decrease in the concentration of 3 proteins, vascular endothelial growth factor (VEGF), placental growth factor (PlGF) and follistatin, in the plasma of women with preeclampsia.

CONCLUSION

Based on our findings, it seems that protein factors may play an important role in the pathogenesis of preeclampsia, and there are many proteins that have not been studied in PE to date. There are no previous studies assessing the LIF, follistatin, HGF, HB-EGF and PDGF-BB concentrations in the plasma of women with PE; therefore, our obtained results indicate that these proteins are new factors that can play an important role in the pathomechanisms of PE.

Involvement of leptin in the molecular physiology of the placenta

Leptin is a homeostatic regulator in the placenta where it promotes proliferation, protein synthesis and the expression of tolerogenic maternal response molecules such as HLA-G. Leptin also exerts an anti-apoptotic action in placenta controlling the expression of p53 master cell cycle regulator under different stress conditions. On the other hand, leptin is an integrative target of different placental stimuli. The expression of leptin in placenta is regulated by hCG, insulin, steroids, hypoxia and many other growth hormones, suggesting that it might have an important endocrine function in the trophoblastic cells. The leptin expression is induced involving the cAMP/PKA or cAMP/Epac pathways which have profound actions upon human trophoblast function. The activation of PI3K and MAPK pathways also participates in the leptin expression. Estrogens play a central role during pregnancy, particularly 17β-estradiol upregulates the leptin expression in placental cells through genomic and non-genomic actions. The leptin promoter analysis reveals specific elements that are active in placental cells. The transcription factors CREB, AP1, Sp1, NFκB and the coactivator CBP are involved in the placental leptin expression. Moreover, placental leptin promoter is a target of epigenetic marks such as DNA methylation and histone acetylation that regulates not only the leptin expression in placenta during pregnancy but also determines the predisposition of acquiring adult metabolism diseases. Taken together, all these results allow a better understanding of leptin function and regulatory mechanisms of leptin expression in human placental trophoblasts, and support the importance of leptin during pregnancy and in programming adult health.

Effect of maternal obesity on birthweight and neonatal fat mass: A prospective clinical trial

OBJECTIVE

To discriminate the effect of maternal obesity and gestational diabetes on birth weight and adipose tissue of the newborn.

METHODS

Normal BMI women (group N, n = 243; 18.5≤ BMI<25 kg/m2) and obese women (group Ob, n = 253; BMI≥30 kg/m2) were recruited in a prospective study between 15 and 18 weeks of gestation. All women were submitted to a 75g oral glucose tolerance test in the second and third trimester. First trimester fasting blood glucose was also obtained from Ob women. All women with one measurement above normal values were considered positive for gestational diabetes and first treated by dietary intervention. When dietary measures were not efficient, they were treated by insulin. Neonatal anthropometrics, sum of skinfolds and cord serum hormones were measured.

RESULTS

222 N and 226 Ob mothers and their newborns were included in the analysis. Diabetes was diagnosed in 20% and 45.2% of N and Ob women, respectively. Birth weight was not statistically different between groups (boys: 3456g±433 and 3392g±463; girls: 3316g±402 and 3391g±408 for N and Ob, respectively). Multivariate analysis demonstrated that skinfold thickness and serum leptin concentrations were significantly increased in girls born to women with obesity (18.0mm±0.6 versus 19.7mm±0.5, p = 0.004 and 11.3ng/mL±1.0 versus 15.3ng/mL±1.0, p = 0.02), but not in boys (18.4mm±0.6 versus 18.5mm±0.5, p = 0.9 and 9.3ng/mL±1.0 versus 9.0ng/mL±1.0, p = 0.9). Based on data from 136 N and 124 Ob women, maternal insulin resistance at 37 weeks was also positively related to skinfold in girls, only, with a 1-point increase in HOMA-IR corresponding to a 0.33mm±0.08 increase in skinfold (p<0.0001).

CONCLUSIONS

Regardless of gestational diabetes, maternal obesity and insulin resistance were associated with increased adiposity in girls only. Persistence of this sexual dimorphism remains to be explored during infancy.

Large Reduction in Adiponectin During Pregnancy Is Associated With Large-for-Gestational-Age Newborns

CONTEXT

Fetuses exposed to an obese intrauterine environment are more likely to be born large-for-gestational age (LGA) and are at increased risk of obesity in childhood and cardiovascular disease and/or type 2 diabetes mellitus as adults, but which factors that influence the intrauterine environment is less clear.

OBJECTIVE

To investigate the association between circulating levels of leptin and adiponectin, measured multiple times during pregnancy, and birth weight and prevalence of LGA or small-for-gestational-age infants. The association between birth weight and messenger RNA (mRNA) expression of adiponectin receptors and genes involved in nutrient transport in the placenta was also investigated.

DESIGN

Population-based prospective cohort [substudy of the STORK study (STORe barn og Komplikasjoner, translated as Large Babies and Complications)] from 2001 to 2008.

SETTING

University hospital. Patients or other participants: 300 women.

MAIN OUTCOME MEASURES

Oral glucose tolerance test was performed twice along with adiponectin and leptin levels measured four times during pregnancy.

RESULTS

Circulating adiponectin was lower in mothers who gave birth to LGA offspring or had fetuses with high intrauterine abdominal circumference late in pregnancy. Adiponectin decreased most from early to late pregnancy in mothers who gave birth to LGA offspring, and the decrease was an independent predictor of birth weight. Adiponectin receptor 2 and system A amino acid transporter mRNA expression in placentas was negatively correlated with birth weight and was lower in placentas from LGA infants.

CONCLUSIONS

Our findings suggest that maternal adiponectin may be an important predictor of fetal growth and birth weight, independent of body mass index and insulin resistance.

A maternal high-fat, high-sucrose diet has sex-specific effects on fetal glucocorticoids with little consequence for offspring metabolism and voluntary locomotor activity in mice

Maternal overnutrition and obesity during pregnancy can have long-term effects on offspring physiology and behaviour. These developmental programming effects may be mediated by fetal exposure to glucocorticoids, which is regulated in part by placental 11β-hydroxysteroid dehydrogenase (11β-HSD) type 1 and 2. We tested whether a maternal high-fat, high-sucrose diet would alter expression of placental 11β-HSD1 and 2, thereby increasing fetal exposure to maternal glucocorticoids, with downstream effects on offspring physiology and behaviour. C57BL/6J mice were fed a high-fat, high-sucrose (HFHS) diet or a nutrient-matched low-fat, no-sucrose control diet prior to and during pregnancy and lactation. At day 17 of gestation, HFHS dams had ~20% lower circulating corticosterone levels than controls. Furthermore, there was a significant interaction between maternal diet and fetal sex for circulating corticosterone levels in the fetuses, whereby HFHS males tended to have higher corticosterone than control males, with no effect in female fetuses. However, placental 11β-HSD1 or 11β-HSD2 expression did not differ between diets or show an interaction between diet and sex. To assess potential long-term consequences of this sex-specific effect on fetal corticosterone, we studied locomotor activity and metabolic traits in adult offspring. Despite a sex-specific effect of maternal diet on fetal glucocorticoids, there was little evidence of sex-specific effects on offspring physiology or behaviour, although HFHS offspring of both sexes had higher circulating corticosterone at 9 weeks of age. Our results suggest the existence of as yet unknown mechanisms that mitigate the effects of altered glucocorticoid exposure early in development, making offspring resilient to the potentially negative effects of a HFHS maternal diet.

Maternal and fetal lipid metabolism under normal and gestational diabetic conditions

Maternal lipids are strong determinants of fetal fat mass. Here we review the overall lipid metabolism in normal and gestational diabetes mellitus (GDM) pregnancies. During early pregnancy, the increase in maternal fat depots is facilitated by insulin, followed by increased adipose tissue breakdown and subsequent hypertriglyceridemia, mainly as a result of insulin resistance (IR) and estrogen effects. The response to diabetes is variable as a result of greater IR but decreased estrogen levels. The vast majority of fatty acids (FAs) in the maternal circulation are esterified and associated with lipoproteins. These are taken up by the placenta and hydrolyzed by lipases. The released FAs enter various metabolic routes and are released into fetal circulation. Although these determinants are modified in maternal GDM, the fetus does not seem to receive more FAs than in non-GDM pregnancies. Long-chain polyunsaturated FAs are essential for fetal development and are obtained from the mother. Mitochondrial FA oxidation occurs in fetal tissue and in placenta and contributes to energy production. Fetal fat accretion during the last weeks of gestation occurs very rapidly and is sustained not only by FAs crossing the placenta, but also by fetal lipogenesis. Fetal hyperinsulinemia in GDM mothers promotes excess accretion of adipose tissue, which gives rise to altered adipocytokine profiles. Fetal lipoproteins are low at birth, but the GDM effects are unclear. The increase in body fat in neonates of GDM women is a risk factor for obesity in early childhood and later life.

Modification of the fatty acid composition of an obesogenic diet improves the maternal and placental metabolic environment in obese pregnant mice

Peri-conceptional exposure to maternal obesogenic nutrition is associated with in utero programming of later-life overweight and metabolic disease in the offspring. We aimed to investigate whether dietary intervention with a modified fatty acid quality in an obesogenic high-calorie (HC) diet during the preconception and gestational phases can improve unfavourable effects of an adipogenic maternal environment. In NMRI mice, peri-conceptional and gestational obesity was induced by feeding a HC diet (controls), and they were compared with dams on a fat-modified (Fat-mod) HC diet of the same energy content but enriched with medium-chain fatty acids (MCFAs) and adjusted to a decreased ratio of n-6 to n-3 long-chain polyunsaturated fatty acids (LC-PUFAs). Effects on maternal and placental outcomes at delivery (day 17.5 post coitum) were investigated. Despite comparable energy assimilation between the two groups of dams, the altered fatty acid composition of the Fat-mod HC diet induced lower maternal body weight, weights of fat depots, adipocyte size, and hepatic fat accumulation compared to the unmodified HC diet group. Further, there was a trend towards lower fasting glucose, insulin and leptin concentrations in dams fed the Fat-mod HC diet. Phenotypic changes were accompanied by inhibition of transcript and protein expression of genes involved in hepatic de novo lipogenesis comprising PPARG2 and its target genes Fasn, Acaca, and Fabp4, whereas regulation of other lipogenic factors (Srebf1, Nr1h3, Abca1) appeared to be more complex. The modified diet led to a sex-specific placental response by upregulating PPARG-dependent fatty acid transport gene expression in female versus male placentae. Qualitative modification of the fatty acid spectrum of a high-energy maternal diet, using a combination of both MCFAs and n-3 LC-PUFAs, seems to be a promising interventional approach to ameliorate the adipogenic milieu of mice before and during gestation.

Gestational Weight Gain and Fetal-Maternal Adiponectin, Leptin, and CRP: results of two birth cohorts studies

Gestational weight gain (GWG) is an important modifiable factor known to influence fetal outcomes including birth weight and adiposity. Unlike behaviors such as smoking and alcohol consumption, the effect of GWG throughout pregnancy on fetal development and other outcomes has not been extensively studied. The aim of this study was to investigate the relationship of GWG with endocrine factors such as adiponectin, leptin, and C-reactive protein which may be associated with inflammatory response, fetal growth, and adiposity later in life. Data were obtained from the Ulm Birth Cohort Study (UBCS) and the Ulm SPATZ Health Study, two methodologically similar birth cohort studies including newborns and their mothers recruited from 11/2000–11/2001 and 04/2012–05/2013. In the two included birth cohorts we consistently observed statistically significant positive associations between GWG beginning as early as the second trimester with fetal cord blood leptin and stronger association beginning as early as the first trimester with post-delivery maternal serum leptin. Total weight gain exceeding commonly accepted recommended guidelines was consistently associated with higher leptin levels in both cord blood and post-delivery maternal serum. These results suggest a potential pathomechanistic link between fetal environment and surrogate markers of long-term health.

Blood-based biomarkers of adverse perinatal outcomes in maternal obesity

OBJECTIVE

Increasing maternal weight has been shown to predict adverse perinatal outcome, including increases in the relative risk of fetal death, stillbirth, neonatal death, perinatal death and infant death. In order to better understand the pathophysiological factors associated with obesity during pregnancy, the role of biomarkers associated with adverse outcomes in obese pregnant women is under investigation. The purpose of this review study was to examine potential biomarkers that could serve as effective screening strategies in obese pregnant women to reduce fetal and neonatal morbidity, as well as maternal morbidity.

METHODS

Electronic databases (Pubmed, Embase) were searched for previously published research studies that investigated biomarkers associated with perinatal outcomes in obese pregnant women and the putative mechanisms underlying biomarker effects on pregnancy outcomes.

RESULTS

It is evident that while several biomarkers predict perinatal complications in obese pregnant women, none fulfilled the criteria to be considered clinically useful.

CONCLUSION

There is a critical need for reliable blood-based biomarkers associated with an increased risk of adverse perinatal outcomes in obese pregnant women.

Leptin and adiponectin as predictors of cardiovascular risk after gestational diabetes mellitus

BACKGROUND

Gestational diabetes mellitus (GDM) is a significant risk factor for cardiovascular disease (CVD) in later life, but the mechanism remains unclear. Adipokine imbalance in the presence of metabolic dysfunction may be a key event in promoting CVD. The aim of the study was to examine the relationships between GDM, cardiovascular risk, and plasma adiponectin, leptin and the leptin/adiponectin (L/A) ratio in pregnancy and at 5 years after the index pregnancy.

METHODS

This population-based prospective cohort included 300 women who had an oral glucose tolerance test (OGTT) during pregnancy. Five years later, the OGTT was repeated along with dual-energy X-ray absorptiometry, lipid analysis, and pulse wave velocity analysis. Fasting adiponectin and leptin levels were measured four times during pregnancy and at follow-up.

RESULTS

We found the L/A ratio higher in GDM women both during pregnancy and follow-up compared to non-GDM women. A high L/A ratio during pregnancy was associated with CV risk based on lipid ratios at follow-up, especially the TG/HDL-C ratio. Further, interaction analysis indicated that an increase in the L/A ratio of 1 unit was associated with a higher CV risk in GDM compared to normal pregnancy. Finally, low adiponectin levels independently predicted increased lipid ratios at follow-up.

CONCLUSIONS

Taken together, our findings suggest that high L/A ratio in pregnancy and in particularly in those with GDM are associated with an unfavorable CVD risk profile during follow-up. Future studies should investigate if a dysregulated leptin and adiponectin profile during pregnancy is associated with atherosclerotic disease during long-term follow-up.

Implications of maternal obesity on fetal growth and the role of ultrasound

Over fifty percent of women entering pregnancy are overweight or obese. This has a significant impact on short and long term maternal and infant health outcomes, and the intergenerational effects of obesity are now a major public health problem globally. Areas covered: There are two major pathways contributing to fetal growth. Glucose and insulin directly affect growth, while other substrates such as leptin, adiponectin and insulin-like growth factors indirectly influence growth through structural and morphological effects on the placenta, uteroplacental blood flow, and regulation of placental transporters. Advances in ultrasonography over the past decade have led to interest in the prediction of the fetus at risk of overgrowth and adiposity utilizing both standard ultrasound biometry and fetal body composition measurements. However, to date there is no consensus regarding the definition of fetal overgrowth, its reporting, and clinical management. Expert commentary: Maternal dietary intervention targeting the antenatal period appear to be too late to sufficiently affect fetal growth. The peri-conceptual period and early pregnancy are being evaluated to determine if the intergenerational effects of maternal obesity can be altered to improve newborn, infant and child health.

The role of leptin in central nervous system diseases

Leptin is a peptide hormone produced by adipose tissue and acts in brain centers to control critical physiological functions. Leptin receptors are especially abundant in the hypothalamus and trigger specific neuronal subpopulations, and activate several intracellular signaling events, including the JAK/STAT, MAPK, PI3K, and mTOR pathway. Although most studies focus on its role in energy intake and expenditure, leptin also plays a critical role in many central nervous system diseases.

Effects of maternal obesity on placental function and fetal development

Obesity has reached epidemic proportions, and pregnancies in obese mothers have increased risk for complications including gestational diabetes, hypertensive disorders, pre-term birth and caesarian section. Children born to obese mothers are at increased risk of obesity and metabolic disease and are susceptible to develop neuropsychiatric and cognitive disorders. Changes in placental function not only play a critical role in the development of pregnancy complications but may also be involved in linking maternal obesity to long-term health risks in the infant. Maternal adipokines, i.e., interleukin 6 (IL-6), tumor necrosis factor alpha (TNF-α), leptin and adiponectin link maternal nutritional status and adipose tissue metabolism to placental function. Adipokines and metabolic hormones have direct impact on placental function by modulating placental nutrient transport. Nutrient delivery to the fetus is regulated by a complex interaction including insulin signaling, cytokine profile and insulin responsiveness, which is modulated by adiponectin and IL-1β. In addition, obese pregnant women are at risk for hypertension and preeclampsia with reduced placental vascularity and blood flow, which would restrict placental nutrient delivery to the developing fetus. These sometimes opposing signals regulating placental function may contribute to the diversity of short and long-term outcomes observed in pregnant obese women. This review focuses on the changes in adipokines and obesity-related metabolic hormones, how these factors influence placental function and fetal development to contribute to long-term metabolic and behavioral consequences of children born to obese mothers.

The roles of leptin and adiponectin at the fetal-maternal interface in humans

Infertility now affects one in seven couples, and the prevalence of this condition continues to increase. Ovulatory defects and unknown causes account for more than half of the cases of infertility. It has been postulated that a significant proportion of these cases are directly or indirectly related to obesity, since the presence of excess adipose tissue has a variety of effects on reproductive function. Here, we review on the effects of the two major adipokines (leptin and adiponectin) on fertility, with a focus on the first steps in embryo implantation and the key components of fetal-maternal interface (the placenta and the endometrium). These adipokines are reportedly involved in the regulation of cell proliferation and differentiation, and as such affect local angiogenesis, immune tolerance and inflammatory processes in placental and endometrial tissues. In placental cells, leptin and adiponectin also modulate trophoblast invasiveness and the nutrient supply. These observations strongly suggest by interfering with the placenta and endometrium, adipokines can create a favorable environment for embryo implantation and have a key role in fetal-maternal metabolism, fetal-maternal communication, and gestation. Given that reproductive functions are tightly coupled to the energy balance, metabolic abnormalities may lead to the development of complications of pregnancy and changes in fetal growth. In this context, we suggest that the leptin/adiponectin ratio may be a clinically valuable marker for detecting a number of pathologies in pregnancy.

Maternal adipokines and insulin as biomarkers of pregnancies complicated by overweight and obesity

BACKGROUND

Maternal obesity is associated with several adverse pregnancy outcomes. This study was conducted aiming to evaluate maternal levels of adipokines and insulin in pregnancies complicated by overweight and obesity and its correlations with maternal and fetal outcomes.

METHODS

This cross-sectional study included 72 mother-newborn pairs. Mothers were classified as having normal weight (n = 23), overweight (n = 18), and obesity (n = 31). Maternal adiponectin, leptin, resistin and insulin levels at the end of pregnancy were compared among groups and correlated with maternal and perinatal outcomes. Data were analyzed by ANOVA and correlation tests, with a p value <0.05 being considered as significant.

RESULTS

Obese pregnant women showed higher leptin levels (p = 0.0021). Leptin levels were positively correlated with prepregnancy body mass index-BMI (r = 0.57), gestational (37 or 38 weeks of gestation) BMI (r = 0.39), hypertension (r = 0.27), and hyperglycemia (r = 0.30), and negatively associated with newborns' abdominal circumference (r = -0.25). Adiponectin concentrations were negatively correlated with gestational BMI (r = -0.29) and newborns' cephalic circumference (r = -0.27) and positively correlated with birth weight (r = 0.23). Insulin concentrations correlated positively with prepregnancy BMI (r = 0.38), gestational BMI (r = 0.24) and maternal hyperglycemia (r = 0.26).

CONCLUSIONS

Our findings support the relationship between markers of obesity and maternal-fetal outcomes. Maternal insulin and adipokines levels showed an independent relationship with mother and newborns outcomes, respectively. In this studied population, the results indirectly reinforce the importance of maternal weight control before and during pregnancy to avoid adverse outcomes to mother and their newborns.

Endosomal system genetics and autism spectrum disorders: A literature review

Autism spectrum disorders (ASDs) are a group of debilitating neurodevelopmental disorders thought to have genetic etiology, due to their high heritability. The endosomal system has become increasingly implicated in ASD pathophysiology. In an attempt to summarize the association between endosomal system genes and ASDs we performed a systematic review of the literature. We searched PubMed for relevant articles. Simons Foundation Autism Research Initiative (SFARI) gene database was used to exclude articles regarding genes with less than minimal evidence for association with ASDs. Our search retained 55 articles reviewed in two categories: genes that regulate and genes that are regulated by the endosomal system. Our review shows that the endosomal system is a novel pathway implicated in ASDs as well as other neuropsychiatric disorders. It plays a central role in aspects of cellular physiology on which neurons and glial cells are particularly reliant, due to their unique metabolic and functional demands. The system shows potential for biomarkers and pharmacological intervention and thus more research into this pathway is warranted.

Maternal obesity (Class I-III), gestational weight gain and maternal leptin levels during and after pregnancy: a prospective cohort study

BACKGROUND

Maternal obesity is accompanied by maternal and fetal complications during and after pregnancy. The risks seem to increase with degree of obesity. Leptin has been suggested to play a role in the development of obesity related complications. Whether maternal leptin levels differ between obese and morbidly obese women, during and after pregnancy, have to our knowledge not been previously described. Neither has the association between maternal leptin levels and gestational weight gain in obese women. The aim was to evaluate if maternal plasma leptin levels were associated with different degrees of maternal obesity and gestational weight gain.

METHODS

Prospective cohort study including women categorized as obesity class I-III (n = 343) and divided into three gestational weight gain groups (n = 304). Maternal plasma leptin was measured at gestational week 15, 29 and 10 weeks postpartum. Maternal Body Mass Index (BMI) was calculated from early pregnancy weight. Gestational weight gain was calculated using maternal weight in delivery week minus early pregnancy weight. The mean value and confidence interval of plasma-leptin were analysed with a two-way ANOVA model. Interaction effect between BMI and gestational weight gain group was tested with a two-way ANOVA model.

RESULTS

The mean maternal leptin concentrations were significantly higher in women with obesity class III compared to women in obesity class I, at all times when plasma leptin were measured. The mean leptin concentrations were also significantly higher in women with obesity class II compared to women in obesity class I, except in gestational week 29. There was no difference in mean levels of plasma leptin between the gestational weight gain groups. No significant interaction between BMI and gestational weight gain group was found.

CONCLUSIONS

Plasma leptin levels during and after pregnancy were associated with obesity class but not with degree of gestational weight gain. These results are in concordance with epidemiological findings where the risk of obstetric complications increases with increased maternal obesity class. The effect on obstetric outcome by degree of gestational weight gain is less pronounced than the adverse effects associated with maternal obesity.

The impact of excessive maternal weight on the nutritional status of the fetus - the role of leptin

INTRODUCTION

Assessment of leptin concentration in the blood of pregnant women (leptin concentration - Lc) and in their newborns, according to their nutritional status.

MATERIAL AND METHODS

Pregnant women (n = 42) were divided into normal body mass (NBM) and excessive body mass (EBM) groups. Neonates were divided into AGA (eutrophic) and LGA (macrosomic) groups. Leptin concentraction was studied in 4 subgroups: NBM/AGA, NBM/LGA, EBM/AGA, EBM/LGA.

RESULTS

Mothers: A significant correlation was found between maternal Lc and body mass index (BMI) (r = 0.75, p < 0.001). Maternal Lc was 3 times higher than neonatal Lc (p < 0.00001). The NBM mothers showed lower Lc compared to EBM mothers (p = 0.000018). Leptin concentration values in NBM/LGA and NBM/AGA mothers were similar (p = 0.6775). Newborns: Correlations were found between Lc and ponderal index (PI) (r = 0.67, p < 0.001), weight (r = 0.43, p = 0.004) and placental weight (r = 0.56, p < 0.001). Girls presented higher Lc than boys (p = 0.0338). In LGA groups, newborns born to EBM mothers presented higher Lc than those born to NBM mothers (p = 0.0013). In both AGA groups, Lc was similar (AGA/EBM vs. AGA/NBM p = 0.1619). The highest Lc and the largest placentas were found in the group of LGA newborns born to EBM mothers.

CONCLUSIONS

Leptin concentration positively correlates with BMI in pregnant women, with PI and female sex in newborns as well as with placental weight. The nutritional status of fetuses does not affect the Lc of their non-obese mothers. The LGA neonates born to EBM women demonstrate higher Lc than LGA neonates born to NBM mothers, whereas Lc of AGA neonates is similar regardless of the nutritional status of their mothers.

Higher maternal leptin levels at second trimester are associated with subsequent greater gestational weight gain in late pregnancy

BACKGROUND

Excessive gestational weight gain (GWG) is associated with adverse pregnancy outcomes. In non-pregnant populations, low leptin levels stimulate positive energy balance. In pregnancy, both the placenta and adipose tissue contribute to circulating leptin levels. We tested whether maternal leptin levels are associated with subsequent GWG and whether this association varies depending on stage of pregnancy and on maternal body mass index (BMI).

METHODS

This prospective cohort study included 675 pregnant women followed from 1(st) trimester until delivery. We collected anthropometric measurements, blood samples at 1(st) and 2(nd) trimester, and clinical data until delivery. Maternal leptin was measured by ELISA (Luminex technology). We classified women by BMI measured at 1(st) trimester: BMI < 25 kg/m(2) = normal weight; 25 ≤ BMI < 30 kg/m(2) = overweight; and BMI ≥ 30 kg/m(2) = obese.

RESULTS

Women gained a mean of 6.7 ± 3.0 kg between 1(st) and 2(nd) trimester (mid pregnancy GWG) and 5.6 ± 2.5 kg between 2(nd) and the end of 3(rd) trimester (late pregnancy GWG). Higher 1(st) trimester leptin levels were associated with lower mid pregnancy GWG, but the association was no longer significant after adjusting for % body fat (%BF; β = 0.38 kg per log-leptin; SE = 0.52; P = 0.46). Higher 2(nd) trimester leptin levels were associated with greater late pregnancy GWG and this association remained significant after adjustment for BMI (β = 2.35; SE = 0.41; P < 0.0001) or %BF (β = 2.01; SE = 0.42; P < 0.0001). In BMI stratified analyses, higher 2(nd) trimester leptin levels were associated with greater late pregnancy GWG in normal weight women (β = 1.33; SE = 0.42; P =0.002), and this association was stronger in overweight women (β = 2.85; SE = 0.94; P = 0.003--P for interaction = 0.05).

CONCLUSIONS

Our results suggest that leptin may regulate weight gain differentially at 1(st) versus 2(nd) trimester of pregnancy: at 2(nd) trimester, higher leptin levels were associated with greater subsequent weight gain--the opposite of its physiologic regulation in non-pregnancy--and this association was stronger in overweight women. We suspect the existence of a feed-forward signal from leptin in second half of pregnancy, stimulating a positive energy balance and leading to greater weight gain.

Maternal High-Fat Diet-Induced Loss of Fetal Oocytes Is Associated with Compromised Follicle Growth in Adult Rat Offspring

Maternal obesity predisposes offspring to metabolic and reproductive dysfunction. We have shown previously that female rat offspring born to mothers fed a high-fat (HF) diet throughout pregnancy and lactation enter puberty early and display aberrant reproductive cyclicity. The mechanisms driving this reproductive phenotype are currently unknown thus we investigated whether changes in ovarian function were involved. Wistar rats were mated and randomized to: dams fed a control diet (CON) or dams fed a HF diet from conception until the end of lactation (HF). Ovaries were collected from fetuses at Embryonic Day (E) 20, and neonatal ovaries at Day 4 (P4), prepubertal ovaries at P27 and adult ovaries at P120. In a subset of offspring, the effects of a HF diet fed postweaning were evaluated. The present study shows that fetuses of mothers fed a HF diet had significantly fewer oocytes at E20, and in neonates, have reduced AMH signaling that may facilitate an increased number of assembled primordial follicles. Both prepubertally and in adulthood, ovaries show increased follicular atresia. As adults, offspring have reduced FSH responsiveness, low expression levels of estrogen receptor alpha (Eralpha), the oocyte-secreted factor, Gdf9, oocyte-specific RNA binding protein, Dazl, and high expression levels of the granulosa-cell derived factor, AMH, in antral follicles. Together, these data suggest that ovarian compromise in offspring born to HF-fed mothers may arise from changes already observable in the fetus and neonate and in the long term, associated with increased follicular atresia through adulthood.

The placenta: a multifaceted, transient organ

The placenta is arguably the most important organ of the body, but paradoxically the most poorly understood. During its transient existence, it performs actions that are later taken on by diverse separate organs, including the lungs, liver, gut, kidneys and endocrine glands. Its principal function is to supply the fetus, and in particular, the fetal brain, with oxygen and nutrients. The placenta is structurally adapted to achieve this, possessing a large surface area for exchange and a thin interhaemal membrane separating the maternal and fetal circulations. In addition, it adopts other strategies that are key to facilitating transfer, including remodelling of the maternal uterine arteries that supply the placenta to ensure optimal perfusion. Furthermore, placental hormones have profound effects on maternal metabolism, initially building up her energy reserves and then releasing these to support fetal growth in later pregnancy and lactation post-natally. Bipedalism has posed unique haemodynamic challenges to the placental circulation, as pressure applied to the vena cava by the pregnant uterus may compromise venous return to the heart. These challenges, along with the immune interactions involved in maternal arterial remodelling, may explain complications of pregnancy that are almost unique to the human, including pre-eclampsia. Such complications may represent a trade-off against the provision for a large fetal brain.