Sex-Specific Placental Responses in Fetal Development

The Role of 11β-Hydroxy Steroid Dehydrogenase Type 2 in Glucocorticoid Programming of Affective and Cognitive Behaviours

Developmental exposure to stress hormones, i.e. glucocorticoids, is central to the process of prenatal programming of later-life health. Glucocorticoid overexposure, through stress or exogenous glucocorticoids, results in a reduced birthweight, as well as affective and neuropsychiatric outcomes in adults, combined with altered hypothalamus-pituitary-adrenal (HPA) axis activity. As such, glucocorticoids are tightly regulated during development through the presence of the metabolizing enzyme 11β-hydroxysteroid dehydrogenase type 2 (HSD2). HSD2 is highly expressed in 2 hubs during development, i.e. the placenta and the fetus itself, protecting the fetus from inappropriate glucocorticoid exposure early in gestation. Through manipulation of HSD2 expression in the mouse placenta and fetal tissues, we are able to determine the relative contribution of glucocorticoid exposure in each compartment. Feto-placental HSD2 deletion resulted in a reduced birthweight and the development of anxiety- and depression-like behaviours in adult mice. The placenta itself is altered by glucocorticoid overexposure, which causes reduced placental weight and vascular arborisation. Furthermore, altered flow and resistance in the umbilical vessels and modification of fetal heart function and development are observed. However, brain-specific HSD2 removal (HSD2BKO) also generated adult phenotypes of depressive-like behaviour and memory deficits, demonstrating the importance of fetal brain HSD2 expression in development. In this review we will discuss potential mechanisms underpinning early-life programming of adult neuropsychiatric disorders and the novel therapeutic potential of statins.

Factors contributing to the variation in placental efficiency on days 70, 90, and 110 of gestation in gilts

Variations in placental efficiency (PE), a measure of grams of fetus produced per gram of placenta, were initially researched between swine breeds, where increased PE was associated with larger litters. Placental efficiency was also found to vary greatly within production herds and individual litters; however, the use of PE as a selection tool has been debated. Nonetheless, PE is an index of feto-placental adaptation and may help identify compensatory mechanisms that maintain fetal growth when placental size is reduced, potentially providing an opportunity to address production concerns like low birth weights and preweaning survival. Since the nutrient transport capacity of the placenta largely depends on vasculature and nutrient transporter abundance, the objectives of this experiment were to 1) determine the mRNA expression of genes encoding nutrient transporters in the placenta and adjacent endometrium, and 2) evaluate if a relationship existed between PE and vascular density and/or nutrient transporters. Gilts (n = 19) were ovario-hysterectomized on day 70, 90, or 110 of gestation to collect placental and adjacent endometrial samples. The mean litter size was 11.1. Placental efficiency increased (P < 0.0001) throughout the end of gestation, while the range of PE increased from day 70 to 90 and was reduced on day 110 (P < 0.0001). Placental efficiency and placental weight were negatively correlated throughout gestation (70 d, r = -0.83, P < 0.0001; 90 d, r = -0.81, P < 0.0001; 110 d, r = -0.44, P < 0.0007), but the negative correlation between PE and fetal weight was not maintained as gestation progressed (70 d, r = -0.58, P < 0.0001; 90 d, r = -0.36, P < 0.0005; 110 d, r = 0.09, P = 0.51). Based on conditional effects plots, variations in PE were associated with alterations in amino acid transporter expression in the placenta (SLC7A7, SLC3A1) and endometrium (SLC7A1) on day 70. On day 90, PE had a positive relationship with placental expression of a glucose transporter (SLC2A3), and on day 110 PE was positively related to placental vascular density. The results suggest utero-placental adaptations occur as a compensation for reduced placental size to meet the increasing nutrient demands of the growing fetus during late gestation in swine. Furthermore, nutrient requirements differ for individual feto-placental units on a given day; therefore, optimizing nutrient availability during late gestation may improve fetal growth and survival.

Prenatal Household Air Pollution Alters Cord Blood Mononuclear Cell Mitochondrial DNA Copy Number: Sex-Specific Associations

Background: Associations between prenatal household air pollution (HAP) exposure or cookstove intervention to reduce HAP and cord blood mononuclear cell (CBMC) mitochondrial deoxyribonucleic acid copy number (mtDNAcn), an oxidative stress biomarker, are unknown. Materials and Methods: Pregnant women were recruited and randomized to one of two cookstove interventions, including a clean-burning liquefied petroleum gas (LPG) stove, or control. Prenatal HAP exposure was determined by serial, personal carbon monoxide (CO) measurements. CBMC mtDNAcn was measured by quantitative polymerase chain reaction. Multivariable linear regression determined associations between prenatal CO and cookstove arm on mtDNAcn. Associations between mtDNAcn and birth outcomes and effect modification by infant sex were explored. Results: LPG users had the lowest CO exposures (p = 0.02 by ANOVA). In boys only, average prenatal CO was inversely associated with mtDNAcn (β = -14.84, SE = 6.41, p = 0.03, per 1ppm increase in CO). When examined by study arm, LPG cookstove had the opposite effect in all children (LPG β = 19.34, SE = 9.72, p = 0.049), but especially boys (β = 30.65, SE = 14.46, p = 0.04), as compared to Control. Increased mtDNAcn was associated with improved birth outcomes. Conclusions: Increased prenatal HAP exposure reduces CBMC mtDNAcn, suggesting cumulative prenatal oxidative stress injury. An LPG stove intervention may reverse this effect. Boys appear most susceptible.

Effects of Arachidonic and Docosohexahenoic Acid Supplementation during Gestation in Rats. Implication of Placental Oxidative Stress

Arachidonic and docosahexaenoic acids (ARA and DHA) are important during pregnancy. However, the effects of dietary supplementation on fetal growth and oxidative stress are inconclusive. We aimed to assess the effect of high ARA and DHA diet during rat gestation on: (1) ARA and DHA availability in plasma and placenta, (2) fetal growth, and (3) placental oxidative stress, analyzing the influence of sex. Experimental diet (ED) was prepared by substituting soybean oil in the control diet (CD) by a fungi/algae-based oil containing ARA and DHA (2:1). Rats were fed with CD or ED during gestation; plasma, placenta, and fetuses were obtained at gestational day 20. DHA, ARA, and their precursors were analyzed in maternal plasma and placenta by gas chromatography/mass spectrophotometry. Fetuses and placentas were weighed, the proportion of fetuses with intrauterine growth restriction (IUGR) determined, and placental lipid and protein oxidation analyzed. ED fetuses exhibited lower body weight compared to CD, being >40% IUGR; fetal weight negatively correlated with maternal plasma ARA, but not DHA. Only ED female placenta exhibited higher lipid and protein oxidation compared to its CD counterparts; lipid peroxidation is negatively associated with fetal weight. In conclusion, high ARA during gestation associates with IUGR, through placental oxidative stress, with females being more susceptible.

Sex differences in the developmental origins of cardiometabolic disease following exposure to maternal obesity and gestational diabetes 1

Over the past 30 years, the worldwide prevalence of obesity has nearly doubled. In addition, more and more women in their child-bearing years are overweight or obese, which increases the risk of gestational diabetes mellitus (GDM). It is increasingly accepted by the scientific community that early life exposure to environmental stress influences the long-term health of an individual, which has been termed the Developmental Origins of Health and Disease theory. Evidence from human cohorts and epidemiological and animal studies has shown that maternal obesity and GDM condition the offspring for cardiometabolic disease development. These effects are most likely regulated by epigenetic mechanisms; however, biological sex is an important factor in defining the risk of the development of several metabolic health disorders. The aim of this review is to describe the current evidence from human cohort and animal model studies that implicates sex differences in the developmental origins of cardiometabolic disease following exposure to maternal obesity and GDM. In addition, this review addresses the potential mechanisms involved in these sex differences. In many studies, sex is ignored as an important variable in disease development; however, the results presented in this review highlight important differences between sexes in the developmental programming of biological responses to exposures during the fetal stage. This knowledge will ultimately help in the development of effective therapeutic strategies for the treatment of cardiometabolic diseases that exhibit sexual dimorphism.

Fetal sex modifies the effect of maternal macronutrient intake on the incidence of small-for-gestational-age births: a prospective observational cohort study

Background

Maternal macronutrient intake is likely to play a pivotal role in fetoplacental growth. Male fetuses grow faster and their growth is more responsive to maternal size.

Objective

We assessed the role of fetal sex in modifying the effect of maternal macronutrient intake on the risk of small-for-gestational-age (SGA) birth.

Design

This was a prospective, observational cohort study of 2035 births from an urban South Asian Indian population. Maternal intakes of total energy and macronutrients were recorded by validated food-frequency questionnaires. The interaction of trimester 1 macronutrient intake with fetal sex was tested on the outcome of SGA births.

Results

The prevalence of SGA was 28%. Trimester 1 macronutrient composition was high in carbohydrate and low in fat (means ± SDs-carbohydrate: 64.6% ± 5.1%; protein: 11.5% ± 1.1%; and fat: 23.9% ± 4.4% of energy). Higher carbohydrate and lower fat consumption were each associated with an increased risk of SGA [adjusted OR (AOR) per 5% of energy (95% CI): carbohydrate: 1.15 (1.01, 1.32); fat: 0.83 (0.71, 0.97)] specifically among male births (males: n = 1047; females: n = 988). Dietary intake of >70% of energy from carbohydrate was also associated with increased risk (AOR: 1.67; 95% CI: 1.00, 2.78), whereas >25% of energy from fat intake was associated with decreased risk (AOR: 0.61; 95% CI: 0.41, 0.90) of SGA in male births.

Conclusions

Higher carbohydrate and lower fat intakes early in pregnancy were associated with increased risk of male SGA births. Therefore, we speculate that fetal sex acts as a modifier of the role of maternal periconceptional nutrition in optimal fetoplacental growth.

Sex Differences in Vulnerability to Prenatal Stress: a Review of the Recent Literature

PURPOSE OF REVIEW

To evaluate the degree to which recent studies provide evidence that the effects of prenatal maternal stress (PNMS) on child health outcomes vary depending on the child's biological sex. In this review, we used a broad definition of stress, including negative life events, psychological stress, and established stress biomarkers. We identified 50 peer-reviewed articles (published January 2015-December 2017) meeting the inclusion criteria.

RECENT FINDINGS

Most articles (k = 35) found evidence of either sex-specific associations (significant in one sex but not the other) or significant PNMSxstress interactions for at least one child health outcome. Evidence for sex-dependent effects was strongest in the group of studies evaluating child neural/nervous system development and temperament as outcomes. There is sufficient evidence of sex-dependent associations to recommend that researchers always consider the potential role of child sex in PNMS programming studies and report descriptive statistics for study outcomes stratified by child biological sex.

Effect of diet in females (F1) from prenatally undernourished mothers on metabolism and liver function in the F2 progeny is sex-specific

PURPOSE

Poor maternal nutrition sensitises to the development of metabolic diseases and obesity in adulthood over several generations. The prevalence increases when offspring is fed with a high-fat (HF) diet after weaning. This study aims to determine whether such metabolic profiles can be transmitted to the second generation and even aggravated when the mothers were exposed to overnutrition, with attention to potential sex differences.

METHODS

Pregnant Wistar rats were subjected to ad libitum (control) or 70% food-restricted diet (FR) during gestation (F0). At weaning, F1 females were allocated to three food protocols: (1) standard diet prior to and throughout gestation and lactation, (2) HF diet prior to and standard diet throughout gestation and lactation, and (3) HF diet prior to and throughout gestation and lactation. F2 offspring was studied between 16 and 32 weeks of age.

RESULTS

FR-F2 offspring on standard diet showed normal adiposity and had no significant metabolic alterations in adulthood. Maternal HF diet resulted in sex-specific effects with metabolic disturbances more apparent in control offspring exposed to HF diet during gestation and lactation. Control offspring displayed glucose intolerance associated with insulin resistance in females. Female livers overexpressed lipogenesis genes and those of males the genes involved in lipid oxidation. Gene expression was significantly attenuated in the FR livers. Increased physical activity associated with elevated corticosterone levels was observed in FR females on standard diet and in all females from overnourished mothers.

CONCLUSIONS

Maternal undernutrition during gestation (F0) improves the metabolic health of second-generation offspring with more beneficial effects in females.

Hypothyroidism and Cognitive Disorders during Development and Adulthood: Implications in the Central Nervous System

Thyroid hormones (THs) play a critical function in fundamental signaling of the body regulating process such as metabolism of glucose and lipids, cell maturation and proliferation, and neurogenesis, to name just a few. THs trigger biological effects both by directly affecting gene expression through the interaction with nuclear receptors (genomic effects) and by activating protein kinases and/or ion channels (short-term effects). For years, a close relationship between the THs hormones and the central nervous system (CNS) has been described, not only for neuronal cells but also for glial development and differentiation. A deficit in thyroid hormones triiodothyronine (T₃) and thyroxine (T₄) is observed in the hypothyroid condition, generated by a iodine deficiency or an autoimmune response of the body. In the hypothyroid condition, several cellular deregulation and alterations have been described in dendrite spine morphology, cell migration and proliferation, and impaired synaptic transmission in the hippocampus, among others. The aim of this review is to describe the role of the thyroid hormones with focus in brain function and neurodegenerative disorders.

Impact of maternal prenatal smoking on fetal to infant neurobehavioral development

Despite recent emphasis on the profound importance of the fetal environment in "programming" postnatal development, measurement of offspring development typically begins after birth. Using a novel coding strategy combining direct fetal observation via ultrasound and actocardiography, we investigated the impact of maternal smoking during pregnancy (MSDP) on fetal neurobehavior; we also investigated links between fetal and infant neurobehavior. Participants were 90 pregnant mothers and their infants (52 MSDP-exposed; 51% minorities; ages 18-40). Fetal neurobehavior at baseline and in response to vibro-acoustic stimulus was assessed via ultrasound and actocardiography at M = 35 weeks gestation and coded via the Fetal Neurobehavioral Assessment System (FENS). After delivery, the NICU Network Neurobehavioral Scale was administered up to seven times over the first postnatal month. MSDP was associated with increased fetal activity and fetal limb movements. Fetal activity, complex body movements, and cardiac-somatic coupling were associated with infants' ability to attend to stimuli and to self-regulate over the first postnatal month. Furthermore, differential associations emerged by MSDP group between fetal activity, complex body movements, quality of movement, and coupling, and infant attention and self-regulation. The present study adds to a growing literature establishing the validity of fetal neurobehavioral measures in elucidating fetal programming pathways.

Alcohol and fetoplacental vasoconstrictor reactivity

Alcohol abuse during pregnancy is a well-known factor in fetal morbidity, including smaller fetal size. We have shown that chronic hypoxia, considered the main pathogenetic factor in intrauterine growth restriction, elevates fetoplacental vascular resistance (and vasoconstrictor reactivity) and thus, presumably, reduces placental blood flow. We thus hypothesized that alcohol may affect the fetus - in addition to other mechanisms - by altering fetoplacental vascular resistance and/or reactivity. Using isolated, double-perfused rat placenta model, we found that maternal alcohol intake in the last third of gestation doubled the vasoconstrictor responses to angiotensin II but did not affect resting vascular resistance. Reactivity to acute hypoxic challenges was unchanged. Chronic maternal alcohol intake in a rat model alters fetoplacental vasculature reactivity; nevertheless, these changes do not appear as serious as other detrimental effects of alcohol on the fetus.

Impacts of bisphenol A (BPA) and phthalate exposures on epigenetic outcomes in the human placenta

The placenta guides fetal growth and development. Bisphenol A (BPA) and phthalates are widespread environmental contaminants and endocrine disruptors, and the placental epigenetic response to these chemicals is an area of growing research interest. Therefore, our objective was to summarize research linking BPA or phthalate exposure to placental outcomes in human pregnancies, with a particular focus on epigenetic endpoints. In PubMed, studies were selected for review (without limiting start date and ending on 1 May 2018) if they reported any direct effects of BPA or phthalates on the placenta in humans. Collectively, available studies suggest that BPA and phthalate exposures are associated with changes to placental micro-RNA expression, DNA methylation, and genomic imprinting. Furthermore, several studies suggest that fetal sex may be an important modifier of placental outcomes in response to these chemicals. Studies in humans demonstrate associations of BPA and phthalate exposure with adverse placental outcomes. Moving forward, more studies should consider sex differences (termed "placental sex") in the measured outcomes, and should utilize appropriate statistical approaches to assess modification by fetal sex. Furthermore, more consistent sample collection and molecular outcome assessment paradigms will be indispensable for making progress in the field. These advances, together with improved non-invasive tools for measuring placental function and outcomes across pregnancy, will be critical for understanding the mechanisms driving placental epigenetic disruption in response to BPA and phthalates, and how these disruptions translate into placental and fetal health.

Sex Differences in Early Embryogenesis: Inter-Chromosomal Regulation Sets the Stage for Sex-Biased Gene Networks: The dialogue between the sex chromosomes and autosomes imposes sexual identity soon after fertilization

Sex-specific transcriptional and epigenomic profiles are detectable in the embryo very soon after fertilization. I propose that in male (XY) and female (XX) pre-implantation embryos sex chromosomes establish sexually dimorphic interactions with the autosomes, before overt differences become apparent and long before gonadogenesis. Lineage determination restricts expression biases between the sexes, but the epigenetic differences are less constrained and can be perpetuated, accounting for dimorphisms that arise later in life. In this way, sexual identity is registered in the epigenome very early in development. As development progresses, sex-specific regulatory modules are harbored within shared transcriptional networks that delineate common traits. In reviewing this field, I propose that analyzing the mechanisms for sexual dimorphisms at the molecular and biochemical level and incorporating developmental and environmental factors will lead to a greater understanding of sex differences in health and disease. Also see the video abstract here: https://youtu.be/9BPlbrHtkHQ.

Implication of Oxidative Stress in Fetal Programming of Cardiovascular Disease

Lifestyle and genetic background are well known risk factors of cardiovascular disease (CVD). A third contributing factor is suboptimal fetal development, due to nutrient or oxygen deprivation, placental insufficiency, or exposure to toxic substances. The fetus adapts to adverse intrauterine conditions to ensure survival; the immediate consequence is low birth weight (LBW) and the long-term effect is an increased susceptibility to develop CVD in adult life. This process is known as Developmental Origins of Health and Disease (DOHaD) or fetal programming of CVD. The influence of fetal life for the future cardiovascular health of the individual has been evidenced by numerous epidemiologic studies in populations suffering from starvation during intrauterine life. Furthermore, experimental animal models have provided support and enabled exploring the underlying mechanisms. Oxidative stress seems to play a central role in fetal programming of CVD, both in the response of the feto-placental unit to the suboptimal intrauterine environment and in the alterations of physiologic systems of cardiovascular control, ultimately leading to disease. This review aims to summarize current knowledge on the alterations in oxidative balance in response to fetal stress factors covering two aspects. Firstly, the evidence from human studies of the implication of oxidative stress in LBW induced by suboptimal conditions during intrauterine life, emphasizing the role of the placenta. In the second part we summarize data on specific redox alterations in key cardiovascular control organs induced by exposure to known stress factors in experimental animals and discuss the emerging role of the mitochondria.

Preconception and prenatal urinary concentrations of phenols and birth size of singleton infants born to mothers and fathers from the Environment and Reproductive Health (EARTH) study

BACKGROUND

Although pregnancy concentrations of some phenols have been associated with infant size at birth, there is limited data on the effect of preconception exposure.

OBJECTIVE

We aimed to examine paternal and maternal preconception and maternal prenatal urinary phenol concentrations in relation to birth weight and head circumference.

METHODS

We evaluated 346 singletons born to 346 mothers and 184 fathers (184 couples) from a prospective preconception cohort of subfertile couples from the Environment and Reproductive Health (EARTH) Study in Boston, USA. We used multiple urine samples collected before the index pregnancy in both men and women to estimate mean preconception urinary benzophenone-3, triclosan, butylparaben, propylparaben, methylparaben, or ethylparaben concentrations. We also estimated mean maternal prenatal urinary phenol concentrations by averaging trimester-specific urine samples. Birth weight and head circumference were abstracted from delivery records. We estimated the association of natural log-phenol concentrations with birth outcomes using multivariable linear regression models, adjusting for known confounders.

RESULTS

In adjusted models, each log-unit increase in paternal preconception benzophenone-3 concentration was associated with a 137 g increase in birth weight (95% CI: 60, 214). Additional adjustment for prenatal benzophenone-3 concentration strengthened this association. None of the maternal preconception phenol concentrations were associated with birth weight. However, maternal prenatal triclosan concentrations were associated with a 38 g decrease in birth weight (95% CI: -76, 0). Few associations were observed between phenols and head circumference except for a decrease of 0.27 cm (95% CI: -54, 0) in relation to maternal preconception methylparaben concentration.

CONCLUSIONS

Although our findings should be interpreted in light of inherent study limitations, these results suggest potential evidence of associations between some paternal or maternal phenol concentrations and birth size.

Effects of excess thromboxane A2 on placental development and nutrient transporters in a Mus musculus model of fetal growth restriction

Hypertensive disease of pregnancy (HDP) with placental insufficiency is the most common cause of fetal growth restriction (FGR) in the developed world. Despite the known negative consequences of HDP both to the mother and fetus, little is known about the longitudinal placental changes that occur as HDP progresses in pregnancy. This is because longitudinal sampling of human placentae during each gestation is impossible. Therefore, using a mouse model of thromboxane A2-analog infusion to mimic human HDP in the last trimester, we calculated placental efficiencies based on fetal and placental weights; quantified spongiotrophoblast and labyrinth thicknesses and vascular density within these layers; examined whether hypoxia signaling pathway involving vascular endothelial growth factor A (VEGFA) and its receptors (VEGFR1, VEGFR2) and matrix metalloproteinases (MMPs) contributed to vascular change; and examined nutrient transporter abundance including glucose transporters 1 and 3 (GLUT1, GLUT3), neutral amino acid transporters 1, 2, and 4 (SNAT1, SNAT2, and SNAT4), fatty acid transporters 2 and 4 (FATP2, FATP4), and fatty acid translocase (CD36) from embryonic day 15.5 to 19 in a 20-day C57Bl/6J mouse gestation. We conclude that early-to-mid gestation hypertensive placentae show compensatory mechanisms to preserve fetal growth by increasing placental efficiencies and maintaining abundance of important nutrient transporters. As placental vascular network diminishes over late hypertension, placental efficiency diminishes and fetal growth fails. Neither hypoxia signaling pathway nor MMPs mediated the vascular diminution in this model. Hypertensive placentae surprisingly exhibit a sex-differential expression of nutrient transporters in late gestation despite showing fetal growth failure in both sexes.

Placental miR-340 mediates vulnerability to activity based anorexia in mice

Anorexia nervosa (AN) is a devastating eating disorder characterized by self-starvation that mainly affects women. Its etiology is unknown, which impedes successful treatment options leading to a limited chance of full recovery. Here, we show that gestation is a vulnerable window that can influence the predisposition to AN. By screening placental microRNA expression of naive and prenatally stressed (PNS) fetuses and assessing vulnerability to activity-based anorexia (ABA), we identify miR-340 as a sexually dimorphic regulator involved in prenatal programming of ABA. PNS caused gene-body hypermethylation of placental miR-340, which is associated with reduced miR-340 expression and increased protein levels of several target transcripts, GR, Cry2 and H3F3b. MiR-340 is linked to the expression of several nutrient transporters both in mice and human placentas. Using placenta-specific lentiviral transgenes and embryo transfer, we demonstrate the key role miR-340 plays in the mechanism involved in early life programming of ABA.

Anorexia nervosa is characterised by self-starvation but its etiology is not completely understood. Here the authors describe how prenatal stress can induce activity-based anorexia in the offspring during early adulthood by upregulating miR-340 expression in the placenta that affects expression of nutrient transporters.

Sex differences in umbilical artery Doppler indices: a longitudinal study

Background

Sexual dimorphism in placental size and function has been described. Whether this influences the clinically important umbilical artery (UA) waveform remains controversial, although a few cross-sectional studies have shown sex differences in UA pulsatility index (PI). Therefore, we tested whether fetal sex influences the UA Doppler indices during the entire second half of pregnancy and aimed to establish sex-specific reference ranges for UA Doppler indices if needed.

Methods

Our main objective was to investigate gestational age-associated changes in UA Doppler indices during the second half of pregnancy and compare the values between male and female fetuses. This was a prospective longitudinal study in women with singleton low-risk pregnancies during 19–40 weeks of gestation. UA Doppler indices were serially obtained at a 4-weekly interval from a free loop of the umbilical cord using color-directed pulsed-wave Doppler ultrasonography. Sex-specific reference intervals were calculated for the fetal heart rate (HR), UA PI, resistance index (RI), and systolic/diastolic ratio (S/D) using multilevel modeling.

Results

Complete data from 294 pregnancies (a total of 1261 observations from 152 male and 142 female fetuses) were available for statistical analysis, and sex-specific reference ranges for the UA Doppler indices and fetal HR were established for the last half of pregnancy. UA Doppler indices were significantly associated with gestational age (P < 0.0001) and fetal HR (P < 0.0001). Female fetuses had 2–8% higher values for UA Doppler indices than male fetuses during gestational weeks 20⁺⁰–36⁺⁶ (P < 0.05), but not later. Female fetuses had higher HR from gestational week 26⁺⁰ until term (P < 0.05).

Conclusions

We have determined gestational age-dependent sex differences in UA Doppler indices and fetal HR during the second half of pregnancy, and correspondingly established new sex-specific reference ranges intended for refining diagnostics and monitoring individual pregnancies.

Maternal Choline Supplementation during Normal Murine Pregnancy Alters the Placental Epigenome: Results of an Exploratory Study

The placental epigenome regulates processes that affect placental and fetal development, and could be mediating some of the reported effects of maternal choline supplementation (MCS) on placental vascular development and nutrient delivery. As an extension of work previously conducted in pregnant mice, the current study sought to explore the effects of MCS on various epigenetic markers in the placenta. RNA and DNA were extracted from placentas collected on embryonic day 15.5 from pregnant mice fed a 1X or 4X choline diet, and were subjected to genome-wide sequencing procedures or mass-spectrometry-based assays to examine placental imprinted gene expression, DNA methylation patterns, and microRNA (miRNA) abundance. MCS yielded a higher (fold change = 1.63-2.25) expression of four imprinted genes (Ampd3, Tfpi2, Gatm and Aqp1) in the female placentas and a lower (fold change = 0.46-0.62) expression of three imprinted genes (Dcn, Qpct and Tnfrsf23) in the male placentas (false discovery rate (FDR) ≤ 0.05 for both sexes). Methylation in the promoter regions of these genes and global placental DNA methylation were also affected (p ≤ 0.05). Additionally, a lower (fold change = 0.3; P_unadjusted = 2.05 × 10^-4; FDR = 0.13) abundance of miR-2137 and a higher (fold change = 1.25-3.92; p < 0.05) expression of its target genes were detected in the 4X choline placentas. These data demonstrate that the placental epigenome is responsive to maternal choline intake during murine pregnancy and likely mediates some of the previously described choline-induced effects on placental and fetal outcomes.

Determinants of prenatal exposure to polybrominated diphenyl ethers (PBDEs) among urban, minority infants born between 1998 and 2006

Polybrominated diphenyl ethers (PBDEs) are environmentally persistent chemicals that structurally resemble legacy pollutants, such as polychlorinated biphenyls (PCBs). PBDEs were added to consumer products for over 30 years, before being phased out due to evidence of toxicity. We examined temporal changes in prenatal exposure to PBDEs, as well as other sources of variation. We measured PBDEs in umbilical cord plasma from 327 minority infants born in New York City between 1998 and 2006. We used linear regression to examine changes in concentrations over time and in relation to lifestyle characteristics collected during pregnancy. We detected BDE-47 in 80% of samples with a geometric mean concentration of 14.1 ng/g lipid. Ethnicity was the major determinant of PBDE exposure; African American infants had 58% higher geometric mean cord plasma concentrations of BDE-47 (p < 0.01) compared to Dominican infants. Notably, African American mothers were more likely to be born in the United States, which itself was associated with 40% (p < 0.01) higher concentrations. We observed small decreases in PBDE concentrations by date of birth and no difference before and after their phase-out in 2004. Final multivariable models explained 8-12% of variability in PBDE concentrations depending on the congener. Our finding that prenatal exposure to PBDEs decreased only modestly between 1998 and 2006 is consistent with the persistent properties of PBDEs and their ongoing release from existing consumer products.

The prorenin receptor in the cardiovascular system and beyond

Since the prorenin receptor (PRR) was first reported, its physiological role in many cellular processes has been under intense scrutiny. The PRR is currently recognized as a multifunctional receptor with major roles as an accessory protein of the vacuolar-type H+-ATPase and as an intermediary in the Wnt signaling pathway. As a member of the renin-angiotensin system (RAS), the PRR has demonstrated to be of relevance in cardiovascular diseases (CVD) because it can activate prorenin and enhance the enzymatic activity of renin, thus promoting angiotensin II formation. Indeed, there is an association between PRR gene polymorphisms and CVD. Independent of angiotensin II, the activation of the PRR further stimulates intracellular signals linked to fibrosis. Studies using tissues and cells from a variety of organs and systems have supported its roles in multiple functions, although some remain controversial. In the brain, the PRR appears to be involved in the central regulation of blood pressure via activation of RAS- and non-RAS-dependent mechanisms. In the heart, the PRR promotes atrial structural and electrical remodeling. Nonetheless, animals overexpressing the PRR do not exhibit cardiac injury. In the kidney, the PRR is involved in the development of ureteric bud branching, urine concentration, and regulation of blood pressure. There is great interest in the PRR contributions to T cell homeostasis and to the development of visceral and brown fat. In this mini-review, we discuss the evidence for the pathophysiological roles of the PRR with emphasis in CVD.

Changes in first trimester fetal CYP1A1 and AHRR DNA methylation and mRNA expression in response to exposure to maternal cigarette smoking

Prenatal exposure to maternal cigarette smoking increases the risk of intrauterine growth retardation, adverse pregnancy outcomes, and diseases later in life. Exposure can result in postnatal global and gene-specific DNA methylation changes, with the latter well documented for the CYP1A1 and AHRR genes involved in the detoxification of xenobiotic substances. This study assessed the impact of exposure to maternal smoking on first trimester fetal CYP1A1 and AHRR mRNA expression and DNA methylation for CpG-sites displaying maternal smoking during pregnancy-mediated methylation changes at birth. The analyses included first trimester (6-12 weeks) placentas (N=39) and livers (N=43). For AHRR, exposure to maternal smoking was associated with increased DNA methylation in the placentas of female fetuses; mRNA expression, however, was unchanged. While exposure to maternal smoking was not associated with AHRR DNA methylation changes in fetal livers; mRNA expression was increased. For CYP1A1, exposure to maternal smoking was not associated with fetal DNA methylation changes whereas mRNA expression increased in placentas and male fetal livers. These results show that first trimester exposure to maternal smoking is associated with CYP1A1 and AHRR DNA methylation and mRNA expression changes. However, the results also indicate that maternal smoking during pregnancy-mediated postnatal CYP1A1 and AHRR DNA methylation changes are not imprinted during the first trimester.

Fetal-sex determination of human placental tissues

It is now demonstrated that the sex-specific maternal-placental-fetal interaction plays an important role in placental functions and pathologies. Determination of fetal-sex may therefore be an important consideration in studies using placenta samples. In this present study, we describe a simple, fast, and cheap protocol, which allows the fetal-sex determination of placental tissues from various starting materials (villi or formalin-fixed, paraffin-embedded (FFPE) tissues, isolated cytotrophoblasts or cellular debris from whole cell lysates, and cDNA) by a single duplex PCR reaction followed by agarose gel electrophoresis.

Maternal Lifetime Stress and Prenatal Psychological Functioning and Decreased Placental Mitochondrial DNA Copy Number in the PRISM Study

Psychosocial stress contributes to placental oxidative stress. Mitochondria are vulnerable to oxidative stress, which can lead to changes in mitochondrial DNA copy number (mtDNAcn). We examined associations of maternal lifetime stress, current negative life events, and depressive and posttraumatic-stress-disorder symptom scores with placental mtDNAcn in a racially/ethnically diverse sample (n = 147) from the Programming of Intergenerational Stress Mechanisms (PRISM) study (Massachusetts, March 2011 to August 2012). In linear regression analyses adjusted for maternal age, race/ethnicity, education, prenatal fine particulate matter exposure, prenatal smoking exposure, and the sex of the child, all measures of stress were associated with decreased placental mtDNAcn (all P values < 0.05). Weighted-quantile-sum (WQS) regression showed that higher lifetime stress and depressive symptoms accounted for most of the effect on mtDNAcn (WQS weights: 0.25 and 0.39, respectively). However, among white individuals, increased lifetime stress and posttraumatic stress disorder symptoms explained the majority of the effect (WQS weights: 0.20 and 0.62, respectively) while among nonwhite individuals, lifetime stress and depressive symptoms accounted for most of the effect (WQS weights: 0.27 and 0.55, respectively). These analyses are first to link increased maternal psychosocial stress with reduced placental mtDNAcn and add to literature documenting racial/ethnic differences in the psychological sequelae of chronic stress that may contribute to maternal-fetal health.

Gestational differences in murine placenta: Glycolytic metabolism and pregnancy parameters

The placenta is a complex and essential organ composed largely of fetal-derived cells, including several different trophoblast subtypes that work in unison to support nutrient transport to the fetus during pregnancy. Abnormal placental development can lead to pregnancy-associated disorders that often involve metabolic dysfunction. The scope of dysregulated metabolism during placental development may not be fully representative of the in vivo state in defined culture systems, such as cell lines or isolated primary cells. Thus, assessing metabolic function in intact placental tissue would provide a better assessment of placental metabolism. In this study, we describe a methodology for assaying glycolytic function in structurally-intact mouse placental tissue, ex vivo, without culturing or tissue dissociation, that more closely resembles the in vivo state. Additionally, we present data highlighting sex-dependent differences of two mouse strains (C57BL/6 and ICR) in the pre-hypertrophic (E14.5) and hypertrophic (E18.5) placenta. These data establish a foundation for investigation of metabolism throughout gestation and provides a comprehensive assessment of glycolytic function during placental development.

Human sperm cryopreservation in cancer patients: Links with deprivation and mortality

Evidence is mounting for a relationship between human semen quality and environmental/lifestyle/socioeconomic factors including long term health outcomes such as mortality. The relationship between pre-freeze and post-thaw semen quality in cancer patients and these factors are unknown. Frozen semen from 217 cancer patients was thawed and analysed using a validated CASA method. Post-thaw quality was matched and compared with WHO semen analysis performed prior to storage. The English Indices of Deprivation 2010 were matched with patients and then examined for relationships with pre-freeze and post-thaw semen quality. There is a relationship between semen quality and deprivation in cancer patients. Compared with pre-freeze semen quality, post-thaw semen quality has a stronger relationship with deprivation. Sperm cryopreservation may have potential as a systemic health diagnostic test and is predictive of cancer patient mortality.

Circulating early- and mid-pregnancy microRNAs and risk of gestational diabetes

AIMS

Epigenetic regulators, including microRNAs (miRNAs), are implicated in type 2 diabetes, but evidence linking circulating miRNAs in pregnancy and risk of gestational diabetes (GDM) is sparse. Potential modifiers, including pre-pregnancy overweight/obesity and offspring sex, are unexamined. We hypothesized that circulating levels of early-mid-pregnancy (range 7-23weeks of gestation) candidate miRNAs are related to subsequent development of GDM. We also hypothesized that miRNA-GDM associations might vary by pre-pregnancy body-mass index (ppBMI) or offspring sex.

METHODS

In a case-control analysis (36GDM cases/80 controls) from the Omega study, a prospective cohort study of pregnancy complications, we measured early-mid-pregnancy plasma levels of 10miRNAs chosen for potential roles in pregnancy course and complications (miR-126-3p, -155-5p, -21-3p, -146b-5p, -210-3p, -222-3p, -223-3p, -517-5p, -518a-3p, and 29a-3p) using qRT-PCR. Logistic regression models adjusted for gestational age at blood draw (GA) were fit to compare circulating miRNAs between cases and controls. We repeated analyses among overweight/obese (ppBMI≥25kg/m²) or lean (ppBMI<25kg/m²) women, and women with male or female offspring separately.

RESULTS

Mean age was 34.3years (cases) and 32.9years (controls). GA-adjusted miR-155-5p (β=0.260/p=0.028) and -21-3p (β=0.316/p=0.005) levels were positively associated with GDM. MiR-146b-5p (β=0.266/p=0.068) and miR-517-5p (β=0.196/p=0.074) were borderline. Associations of miR-21-3p and miR-210-3p with GDM were observed among overweight/obese but not lean women. Associations of six miRNAs (miR-155-5p, -21-3p, -146b-5p, -223-3p, -517-5p, and -29a-3p) with GDM were present only among women carrying male fetuses (all p<0.05).

CONCLUSIONS

Circulating early-mid-pregnancy miRNAs are associated with GDM, particularly among women who are overweight/obese pre-pregnancy or pregnant with male offspring. This area has potential to clarify mechanisms underlying GDM pathogenesis and identify at-risk mothers earlier in pregnancy.

Long-term effects of maternal calcium supplementation on childhood growth differ between males and females in a population accustomed to a low calcium intake

The importance of adequate calcium intakes for healthy growth and bone development has long been recognised. Recent evidence suggests that calcium supplementation may have sex-specific effects on bone growth in childhood. The aim was to describe the long-term effects of calcium supplementation in pregnant Gambian women with a low calcium intake (ISCRTN96502494) on offspring height, weight, bone and body composition in childhood, and whether the effects differ by sex. Children of mothers who participated in the original calcium supplementation trial were measured at age 8-12years using dual-energy X-ray absorptiometry and peripheral quantitative computed tomography. Linear models tested for sex*supplement interactions before and after adjusting for current age and size in early life. 447 children, aged 9.2(SD 0.9) years, were measured. Significant sex*supplement interactions (p<0.05) were observed for many of the anthropometric and bone outcomes, Females whose mothers received calcium (F-Ca) were shorter, lighter with smaller bones and less bone mineral than those whose mothers received placebo (F-P), differences (SE) ranged from height=-1.0 (0.5)% to hip BMC -5.5 (2.3)%. Males from mothers in the calcium group (M-Ca) had greater mid-upper arm circumference (MUAC) (+2.0 (1.0)%, p=0.05) and fat mass (+11.6 (5.1)%, p=0.02) and tended towards greater BMC and size than those whose mothers were in the placebo group (M-P). The differences in anthropometry and body composition were robust to adjustment for current height and weight, whereas all bone differences became non-significant. F-P were taller with more BMC than M-P, whereas F-Ca had similar sized bones and mineral content to M-Ca. Calcium supplementation of pregnant women with low calcium intakes altered the childhood trajectories of growth and bone and body composition development of their offspring in a sex-specific manner, resulting in slower growth among females compared to placebo and accelerated growth among males by age 8-12years.

Multigenerational analysis of sex-specific phenotypic differences at midgestation caused by abnormal folate metabolism

The exposure to adverse environmental conditions (e.g. poor nutrition) may lead to increased disease risk in an individual and their descendants. In some cases, the results may be sexually dimorphic. A range of phenotypes has been associated with deficiency in or defective metabolism of the vitamin folate. However, the molecular mechanism linking folate metabolism to development is still not well defined nor is it clear whether phenotypes are sex-specific. The enzyme methionine synthase reductase (MTRR) is required for the progression of folate metabolism and the utilization of methyl groups from the folate cycle. Previously, we showed that the hypomorphic Mtrr^gt mutation in mice results in metabolic disruption, epigenetic instability, and a wide spectrum of developmental phenotypes (e.g. growth defects, congenital malformations) at midgestation that appear in subsequent wild-type generations. This transgenerational effect only occurs through the maternal lineage. Here, we explore whether the phenotypes that result from either intrinsic or ancestral Mtrr deficiency are sexually dimorphic. We found that no sexual dimorphism is apparent in either situation when the phenotypes were broadly or specifically defined. However, when we focused on the group of phenotypically normal conceptuses derived from maternal grandparental Mtrr deficiency, we observed an apparent increase in placental efficiency in each subsequent generation leading to F4 generation female embryos that weigh more than controls. These data suggest that ancestral abnormal folate metabolism may lead to male grandprogeny that are less able to adapt or female grandprogeny that are programmed to become more sensitive to folate availability in subsequent generations.

Prenatal Serum Concentrations of Brominated Flame Retardants and Autism Spectrum Disorder and Intellectual Disability in the Early Markers of Autism Study: A Population-Based Case-Control Study in California

BACKGROUND

Prior studies suggest neurodevelopmental impacts of polybrominated diphenyl ethers (PBDEs), but few have examined diagnosed developmental disorders.

OBJECTIVES

Our aim was to determine whether prenatal exposure to brominated flame retardants (BFRs) is associated with autism spectrum disorder (ASD) or intellectual disability without autism (ID).

METHODS

We conducted a population-based case-control study including children with ASD (n=545) and ID (n=181) identified from the California Department of Developmental Services and general population (GP) controls (n=418) from state birth certificates. ASD cases were matched to controls by sex, birth month, and birth year. Concentrations of 10 BFRs were measured in maternal second trimester serum samples stored from routine screening. Logistic regression was used to calculate crude and adjusted odds ratios (AOR) for associations with ASD, and separately for ID, compared with GP controls, by quartiles of analyte concentrations in primary analyses.

RESULTS

Geometric mean concentrations of five of the six congeners with ≥55% of samples above the limit of detection were lower in mothers of children with ASD or ID than in controls. In adjusted analyses, inverse associations with several congeners were found for ASD relative to GP (e.g., quartile 4 vs. 1, BDE-153: AOR=0.56, 95% CI: 0.38, 0.84). When stratified by child sex (including 99 females with ASD, 77 with ID, and 73 with GP), estimates were consistent with overall analyses in boys, but in the opposite direction among girls, particularly for BDE-28 and -47 (AOR=2.58, 95% CI: 0.86, 7.79 and AOR=2.64, 95% CI: 0.97, 7.19, respectively). Similar patterns overall and by sex were observed for ID.

CONCLUSIONS

Contrary to expectation, higher PBDE concentrations were associated with decreased odds of ASD and ID, though not in girls. These findings require confirmation but suggest potential sexual dimorphism in associations with prenatal exposure to BFRs. https://doi.org/10.1289/EHP1079.

Prenatal Major Depressive Disorder, Placenta Glucocorticoid and Serotonergic Signaling, and Infant Cortisol Response

OBJECTIVES

Extending prior studies of prenatal adversity and depressive symptoms, we tested associations between maternal prenatal major depressive disorder (MDD) and infant cortisol regulation. Based on prior findings by our group, we also tested placenta glucocorticoid (HSD11B2 methylation) and serotonin (SLC6A4 gene expression) signaling as moderators of links between prenatal MDD and infant cortisol.

METHODS

Participants were 153 mother-infant pairs from a low-income, diverse sample (M [SD] age = 26 [6] years). Repeated structured diagnostic interviews were used to identify mothers with (a) prenatal MDD, (b) preconception-only MDD, and (c) controls. Placenta samples were assayed for HSD11B2 methylation and SLC6A4 gene expression. Infant salivary cortisol response to a neurobehavioral examination was assessed at 1 month.

RESULTS

Daughters of prenatal MDD mothers had 51% higher baseline (ratio = 1.51; 95% confidence interval [CI] = 1.01-2.27; p = .045) and 64% higher stress responsive cortisol (ratio = 1.64; 95% CI = 1.05-2.56; p = .03) than daughters of controls and 75% higher stress-responsive cortisol (ratio = 1.75; 95% CI = 1.04-2.94; p = .04) than daughters of preconception-only MDD mothers. HSD11B2 methylation moderated links between prenatal MDD and baseline cortisol (p = .02), with 1% methylation decreases associated with 9% increased baseline cortisol in infants of prenatal MDD mothers (ratio = 1.09; 95% CI = 1.01-1.16). SLC6A4 expression moderated links between prenatal MDD and cortisol response among boys alone (p = .007), with 10-fold increases in expression associated with threefold increases in stress-responsive cortisol (ratio = 2.87; 95% CI = 1.39-5.93) in sons of control mothers.

CONCLUSIONS

Results highlight specificity of associations between prenatal versus preconception MDD and cortisol regulation and the importance and complexity of placenta glucocorticoid and serotonergic pathways underlying the intergenerational transmission of risk from maternal adversity.

Prenatal stress affects placental cytokines and neurotrophins, commensal microbes, and anxiety-like behavior in adult female offspring

Recent studies demonstrate that exposure to stress changes the composition of the intestinal microbiota, which is associated with development of stress-induced changes to social behavior, anxiety, and depression. Stress during pregnancy has also been related to the emergence of these disorders; whether commensal microbes are part of a maternal intrauterine environment during prenatal stress is not known. Here, we demonstrate that microbiome changes are manifested in the mother, and also found in female offspring in adulthood, with a correlation between stressed mothers and female offspring. Alterations in the microbiome have been shown to alter immune responses, thus we examined cytokines in utero. IL-1β was increased in placenta and fetal brain from offspring exposed to the prenatal stressor. Because IL-1β has been shown to prevent induction of brain derived neurotrophic factor (BDNF), we examined BDNF and found a reduction in female placenta and adult amygdala, suggesting in utero impact on neurodevelopment extending into adulthood. Furthermore, gastrointestinal microbial communities were different in adult females born from stressed vs. non-stressed pregnancies. Adult female offspring also demonstrated increased anxiety-like behavior and alterations in cognition, suggesting a critical window where stress is able to influence the microbiome and the intrauterine environment in a deleterious manner with lasting behavioral consequences. The microbiome may be a key link between the intrauterine environment and adult behavioral changes.

The association between placental histopathology and autism spectrum disorder

INTRODUCTION

Research suggests that autism spectrum disorder (ASD) has its origins in utero. This study examines the association between evidence of placental histopathology and ASD.

METHODS

Administrative claims data and medical records data were used to identify ASD cases (N = 55) and matched controls (N = 199) born at New York Methodist Hospital between 2007 and 2014 and subsequently seen in affiliated pediatrics clinics. Placentas from all births during this time period were reviewed as part of routine care. Data were analyzed using conditional logistic regression to account for the matched (gender, gestational age, and birth weight) design.

RESULTS

Acute placental inflammation, regardless of type was associated with an increased risk of ASD (odds ratio [OR] = 3.14, 95% CI = 1.39, 6.95). Chronic uteroplacental vasculitis (OR = 7.13; 95% CI = 1.17, 43.38), the fetal inflammatory response in the chorionic plate vessels (OR = 5.12; 95% CI = 2.02, 12.96), and maternal vascular malperfusion pathology (OR = 12.29; 95% CI = 1.37, 110.69) were associated with an increased risk of ASD. Placental villous edema was associated with a decreased risk of ASD (OR = 0.05; 95% CI = 0.0005, 0.42). In subanalyses among male placentas acute inflammation overall, fetal inflammatory response in the chorionic plate vessels, and maternal vascular malperfusion pathology remained significantly associated with an increased risk of ASD whereas placental villous edema remained associated with a decreased risk of ASD.

DISCUSSION

Histologic evidence of placental inflammation and maternal vascular malperfusion pathology are associated with ASD.

The aquaglyceroporin AQP9 contributes to the sex-specific effects of in utero arsenic exposure on placental gene expression

BACKGROUND

Sex-specific factors play a major role in human health and disease, including responses to environmental stresses such as toxicant exposure. Increasing evidence suggests that such sex differences also exist during fetal development. In a previous report using the resources of the New Hampshire Birth Cohort Study (NHBCS), we found that low-to-moderate in utero exposure to arsenic, a highly toxic and widespread pollutant, was associated with altered expression of several key developmental genes in the fetal portion of the placenta. These associations were sex-dependent, suggesting that in utero arsenic exposure differentially impacts male and female fetuses. In the present study, we investigated the molecular basis for these sex-specific responses to arsenic.

METHODS

Using NanoString technology, we further analyzed the fetal placenta samples from the NHBCS for the expression of genes encoding arsenic transporters and metabolic enzymes. Multivariable linear regression analysis was used to examine their relationship with arsenic exposure and with key developmental genes, after stratification by fetal sex.

RESULTS

We found that maternal arsenic exposure was strongly associated with expression of the AQP9 gene, encoding an aquaglyceroporin transporter, in female but not male fetal placenta. Moreover, AQP9 expression associated with that of a subset of female-specific arsenic-responsive genes.

CONCLUSIONS

Our results suggest that AQP9 is upregulated in response to arsenic exposure in female, but not male, fetal placenta. Based on these results and prior studies, increased AQP9 expression may lead to increased arsenic transport in the female fetal placenta, which in turn may alter the expression patterns of key developmental genes that we have previously shown to be associated with arsenic exposure. Thus, this study suggests that AQP9 may play a role in the sex-specific effects of in utero arsenic exposure.

Effects of maternal diabetes and fetal sex on human placenta mitochondrial biogenesis

Abnormal placental function in maternal diabetes affects fetal health and can predispose offspring to metabolic diseases in later life. There are fetal sex-specific differences in placenta structure and gene expression, which may affect placental responses to maternal diabetes. The present study examined the effects of maternal diabetes on indices of mitochondrial biogenesis in placentae from male and female offspring. Mitochondrial DNA (mtDNA) copy number and expression of key regulators of mitochondrial biogenesis were assessed in placentae from 19 diabetic and 23 non-diabetic women. The abundance of peroxisome proliferator-activated receptor-γ coactivator-1α (PGC-1α) and mitochondria transcription factor A (TFAM) were lower in female placentae compared to males, but not mtDNA content. In male offspring, maternal diabetes was associated with decreased placental PGC-1α and TFAM, and mitochondrial DNA (mtDNA) content. Male placental TFAM levels were highly correlated with PGC-1α and mtDNA content. However, despite decreased PGC-1α, concomitant changes in TFAM and mtDNA content by diabetes were not observed in females. In addition, TFAM abundance in female placentae was not correlated with PGC-1α or mtDNA content. In summary, placental PGC-1α/TFAM/mitochondrial biogenesis pathway is affected by maternal diabetes and offspring sex. Decreased PGC-1α in response to maternal diabetes plausibly contributes to impaired mitochondrial biogenesis in placentae of male offspring, which may affect long-term health and explain some of enhanced risk of future metabolic diseases in males.

Placental Origins of Chronic Disease

Epidemiological evidence links an individual's susceptibility to chronic disease in adult life to events during their intrauterine phase of development. Biologically this should not be unexpected, for organ systems are at their most plastic when progenitor cells are proliferating and differentiating. Influences operating at this time can permanently affect their structure and functional capacity, and the activity of enzyme systems and endocrine axes. It is now appreciated that such effects lay the foundations for a diverse array of diseases that become manifest many years later, often in response to secondary environmental stressors. Fetal development is underpinned by the placenta, the organ that forms the interface between the fetus and its mother. All nutrients and oxygen reaching the fetus must pass through this organ. The placenta also has major endocrine functions, orchestrating maternal adaptations to pregnancy and mobilizing resources for fetal use. In addition, it acts as a selective barrier, creating a protective milieu by minimizing exposure of the fetus to maternal hormones, such as glucocorticoids, xenobiotics, pathogens, and parasites. The placenta shows a remarkable capacity to adapt to adverse environmental cues and lessen their impact on the fetus. However, if placental function is impaired, or its capacity to adapt is exceeded, then fetal development may be compromised. Here, we explore the complex relationships between the placental phenotype and developmental programming of chronic disease in the offspring. Ensuring optimal placentation offers a new approach to the prevention of disorders such as cardiovascular disease, diabetes, and obesity, which are reaching epidemic proportions.

Human relaxins (RLNH1, RLNH2), their receptor (RXFP1) and fetoplacental growth

Relaxin, a systemic and placental hormone, has potential roles in fetoplacental growth. Human placenta expresses two RLN genes, RLNH1 and RLNH2 Maternal obesity is common and is associated with abnormal fetal growth. Our aims were to relate systemic and cord blood RLNH2, placental RLNs and their receptor (RXFP1) with fetoplacental growth in context of maternal body mass index, and associations with insulin-like growth factor 2 (IGF2) and vascular endothelial growth factor A (VEGFA) in the same placentas. Systemic, cord blood and placental samples were collected prior to term labor, divided by prepregnancy body mass index: underweight/normal (N = 25) and overweight/obese (N = 44). Blood RLNH2 was measured by ELISA; placental RLNH2, RLNH1, RXFP1, IGF2 and VEGFA were measured by quantitative immunohistochemistry and mRNAs were measured by quantitative reverse transcription PCR. Birthweight increased with systemic RLNH2 only in underweight/normal women (P = 0.036). Syncytiotrophoblast RLNH2 was increased in overweight/obese patients (P = 0.017) and was associated with placental weight in all subjects (P = 0.038). RLNH1 had no associations with birthweight or placental weight, but was associated with increased trophoblast and endothelial IGF2 and VEGFA, due to female fetal sex. Thus, while systemic RLNH2 may be involved in birthweight regulation in underweight/normal women, placental RLNH2 in all subjects may be involved in placental weight. A strong association of trophoblast IGF2 with birthweight and placental weight in overweight/obese women suggests its importance. However, an association of only RLNH1 with placental IGF2 and VEGFA was dependent upon female fetal sex. These results suggest that both systemic and placental RLNs may be associated with fetoplacental growth.

Sex-specific associations of maternal birthweight with offspring birthweight in the Omega study

PURPOSE

We investigated nonlinear and offspring sex-specific associations of maternal birthweight (BW) with offspring BW among participants of the Omega study, a pregnancy cohort.

METHODS

Maternal BW was modeled as a continuous variable, linear spline and binary variable indicating low birthweight (LBW; <2500 vs. ≥2500 grams). Offspring BW was modeled as a continuous and binary variable in regression models. Nonlinearity was assessed using likelihood ratio tests (LRTs) in marginal linear spline models.

RESULTS

For every 100-gram increase of maternal BW, offspring BW increased by 22.29 (95% CI: 17.57, 27.02) or 23.41 (95% CI: 6.87, 39.96) grams among mothers with normal BW or born macrosomic, respectively, but not among LBW mothers (β = -8.61 grams; 95% CI: -22.88, 5.65; LRT P-value = .0005). For every 100-gram increase in maternal BW, BW of male offspring increased 23.47 (95% CI: 16.75, 30.19) or 25.21 (95% CI: 4.35, 46.07) grams among mothers with normal BW or born macrosomic, respectively, whereas it decreased 31.39 grams (95% CI: -51.63, -11.15) among LBW mothers (LRT P-value < .0001). Corresponding increases in BW of female offspring (16-22 grams) did not differ among mothers with LBW, normal BW or macrosomia (LRT P-value = .9163).

CONCLUSIONS

Maternal and offspring BW associations are evident among normal BW and macrosomic mothers. These associations differ by offspring sex.

Anti-human platelet antigen (HPA)-1a antibodies may affect trophoblast functions crucial for placental development: a laboratory study using an in vitro model

BACKGROUND

Fetal and neonatal alloimmune thrombocytopenia (FNAIT) is a bleeding disorder caused by maternal antibodies against paternal human platelet antigens (HPAs) on fetal platelets. Antibodies against HPA-1a are accountable for the majority of FNAIT cases. We have previously shown that high levels of maternal anti-HPA-1a antibodies are associated with clinically significant reduced birth weight in newborn boys. Chronic inflammatory placental lesions are associated with increased risk of reduced birth weight and have previously been reported in connection with FNAIT pregnancies. The HPA-1a epitope is located on integrin β3 that is associated with integrin αIIb (the fibrinogen receptor) on platelets and megakaryocytes. Integrin β3 is also associated with integrin αV forming the αVβ3 integrin heterodimer, the vitronectin receptor, which is expressed on various cell types, including trophoblast cells. It is therefore thinkable that maternal anti-HPA-1a antibodies present during early pregnancy may affect placenta function through binding to the HPA-1a antigen epitope on invasive throphoblasts. The aim of the study was to examine whether interaction of a human anti-HPA-1a monoclonal antibody (mAb) with HPA-1a on trophoblast cells affect adhesion, migration and invasion of extravillous trophoblast cells.

METHODS

An in vitro model with human anti-HPA-1a mAb, clone 26.4, and the first trimester extravillous trophoblast cell line HTR8/SVneo was employed. The xCELLigence system was utilized to assess the possible effect of anti-HPA-1a mAb on adhesion and migration of HTR8/SVneo cells. Specially designed chambers precoated with Matrigel were used to assess the effect on the invasive capacity of cells.

RESULTS

We found that human anti-HPA-1a mAb 26.4 partially inhibits adhesion and migratory capacity of HTR8/SVneo cells.

CONCLUSIONS

Our findings suggest that anti-HPA-1a antibodies may affect trophoblast functions crucial for normal placental development. Future studies including primary throphoblast cells and polyclonal anti-HPA-1a antibodies are needed to confirm these results.

Maternal urinary phthalates and sex-specific placental mRNA levels in an urban birth cohort

BACKGROUND

Prenatal urinary concentrations of phthalates in women participants in an urban birth cohort were associated with outcomes in their children related to neurodevelopment, autoimmune disease risk, and fat mass at 3,5,7, and 8 years of life. Placental biomarkers and outcomes at birth may offer biologic insight into these associations. This is the first study to address these associations with candidate genes from the phthalate and placenta literature, accounting for sex differences, and using absolute quantitation methods for mRNA levels.

METHODS

We measured candidate mRNAs in 180 placentas sampled at birth (HSD17B1, AHR, CGA, CYP19A1, SLC27A4, PTGS2, PPARG, CYP11A1) by quantitative PCR and an absolute standard curve. We estimated associations of log_e mRNA with quartiles of urinary phthalate monoesters using linear mixed models. Phthalate metabolites (N = 358) and mRNAs (N = 180) were transformed to a z-score and modeled as independent, correlated vectors in relation to large for gestational age (LGA) and gestational diabetes mellitus (GDM).

RESULTS

CGA was associated with 4 out of 6 urinary phthalates. CGA was 2.0 log_e units lower at the 3^rd vs. 1^st quartile of mono-n-butyl phthalate (MnBP) (95% confidence interval (CI): -3.5, -0.5) in male placentas, but 0.6 log_e units higher (95% CI: -0.8, 1.9) in female placentas (sex interaction p = 0.01). There was an inverse association of MnBP with PPARG in male placentas (-1.1 log_e units at highest vs. lowest quartile, 95% CI: -2.0, -0.1). CY19A1, CYP11A1, CGA were associated with one or more of the following in a sex-specific manner: monobenzyl phthalate (MBzP), MnBP, mono-iso-butyl phthalate (MiBP). These 3 mRNAs were lower by 1.4-fold (95% CI: -2.4, -1.0) in male GDM placentas vs. female and non-GDM placentas (p-value for interaction = 0.04). The metabolites MnBP/MiBP were 16% higher (95% CI: 0, 22) in GDM pregnancies.

CONCLUSIONS

Prenatal concentrations of certain phthalates and outcomes at birth were modestly associated with molecular changes in fetal placental tissue during pregnancy. Associations were stronger in male vs. female placentas, and associations with MnBP and MiBP were stronger than other metabolites. Placental mRNAs are being pursued further as potential mediators of exposure-induced risks to the health of the child.

Effects of prenatal exposure to endocrine disruptors and toxic metals on the fetal epigenome

Exposure to environmental contaminants during pregnancy has been linked to adverse outcomes at birth and later in life. The link between prenatal exposures and latent health outcomes suggests that these exposures may result in long-term epigenetic reprogramming. Toxic metals and endocrine disruptors are two major classes of contaminants that are ubiquitously present in the environment and represent threats to human health. In this review, we present evidence that prenatal exposures to these contaminants result in fetal epigenomic changes, including altered global DNA methylation, gene-specific CpG methylation and microRNA expression. Importantly, these changes may have functional cellular consequences, impacting health outcomes later in life. Therefore, these epigenetic changes represent a critical mechanism that warrants further study.

Effects of prenatal exposure to endocrine disruptors and toxic metals on the fetal epigenome

Exposure to environmental contaminants during pregnancy has been linked to adverse outcomes at birth and later in life. The link between prenatal exposures and latent health outcomes suggests that these exposures may result in long-term epigenetic reprogramming. Toxic metals and endocrine disruptors are two major classes of contaminants that are ubiquitously present in the environment and represent threats to human health. In this review, we present evidence that prenatal exposures to these contaminants result in fetal epigenomic changes, including altered global DNA methylation, gene-specific CpG methylation and microRNA expression. Importantly, these changes may have functional cellular consequences, impacting health outcomes later in life. Therefore, these epigenetic changes represent a critical mechanism that warrants further study.

Sexual epigenetic dimorphism in the human placenta: implications for susceptibility during the prenatal period

AIM

Sex-based differences in response to adverse prenatal environments and infant outcomes have been observed, yet the underlying mechanisms for this are unclear. The placental epigenome may be a driver of these differences.

METHODS

Placental DNA methylation was assessed at more than 480,000 CpG sites from male and female infants enrolled in the extremely low gestational age newborns cohort (ELGAN) and validated in a separate US-based cohort. The impact of gestational age on placental DNA methylation was further examined using the New Hampshire Birth Cohort Study for a total of n = 467 placentas.

RESULTS

A total of n = 2745 CpG sites, representing n = 587 genes, were identified as differentially methylated (p < 1 × 10^-7). The majority (n = 582 or 99%) of these were conserved among the New Hampshire Birth Cohort. The identified genes encode proteins related to immune function, growth/transcription factor signaling and transport across cell membranes.

CONCLUSION

These data highlight sex-dependent epigenetic patterning in the placenta and provide insight into differences in infant outcomes and responses to the perinatal environment.

Dimorphic placental stress: A repercussion of interaction between endocrine disrupting chemicals (EDCs) and fetal sex

Placental homeostasis is critical for fetal development as it determines the health of mother and fetus during pregnancy and in later life. Interestingly even the fetus, in a sexually dimorphic manner, influences the pedantic growth and development of placenta. Although placenta is thought to act as a protective barrier against chemical exposures, certain endocrine disrupting chemicals (EDCs) that are circulating in mother's blood tend to cross placenta. These EDCs have been reported to cause changes in expression levels of certain genes, immunogenic factors and non-coding RNAs such as micro RNA (miRNA) and long non-coding RNA (lncRNA) leading to placental stress. We hypothesize that these changes in placenta occur in a sexually dimorphic manner as a result of interaction between EDC exposure and fetal sex. Therefore, we propose that the ability of placenta to respond and buffer EDC exposure depends on fetal sex and, hence the EDC associated disease susceptibility of one sex differs from the other.

The Association between Sex and Long-Term Pediatric Cardiovascular Morbidity

OBJECTIVE

To evaluate the association between sex and long-term pediatric cardiovascular morbidity.

STUDY DESIGN

A population-based cohort study was performed that compared the risk of long-term cardiovascular morbidity (up to the age of 18 years) of children according to sex. Deliveries occurred between the years 1991 and 2013 in a tertiary medical center. Multiple pregnancies and fetal congenital malformations were excluded. Kaplan-Meier survival curves were constructed to compare cumulative cardiovascular morbidity incidence. A Cox proportional hazards model was used to control for confounders, including gestational age at birth, birth weight, and maternal factors.

RESULTS

During the study period, 240 953 newborns met the inclusion criteria and were included in the long-term analysis. Of them, 51.0% (n = 122 840) were male and 49.0% (n = 118 113) female. Cardiovascular morbidity up to the age of 18 years was significantly more common in male as compared with female newborns (0.3% vs 0.2%, OR 1.33, 95% CI 1.12-1.57, P = .001). In the Cox regression model, male sex exhibited an independent association with long-term cardiovascular morbidity with an adjusted hazard ratio of 1.37 (95% CI 1.16-1.63, P <.001).

CONCLUSION

Male newborns are at an increased risk for pediatric cardiovascular morbidity independent of gestational age at birth and birth weight.

Review: Sexual dimorphism in the formation, function and adaptation of the placenta

Exposure of the embryo or fetus to perturbations in utero can result in intrauterine growth restriction, a primary risk factor for the development of adult disease. However, despite similar exposures, males and females often have altered disease susceptibility or progression from different stages of life. Fetal growth is largely mediated by the placenta, which, like the fetus is genetically XX or XY. The placenta and its associated trophoblast lineages originate from the trophectoderm (TE) of the early embryo. Rodent models (rat, mouse, spiny mouse), have been used extensively to examine placenta development and these have demonstrated the growth trajectory of the placenta in females is generally slower compared to males, and also shows altered adaptive responses to stressful environments. These placental adaptations are likely to depend on the type of stressor, duration, severity and the window of exposure during development. Here we describe the divergent developmental pathways between the male and female placenta contributing to altered differentiation of the TE derived trophoblast subtypes, placental growth, and formation of the placental architecture. Our focus is primarily genetic or environmental perturbations in rodent models which show altered placental responsiveness between sexes. We suggest that perturbations during early placental development may have greater impact on viability and growth of the female fetus whilst those occurring later in gestation may preferentially affect the male fetus. This may be of great relevance to human pregnancies which result from assisted reproductive technologies or complications such as pre-eclampsia and diabetes.