The Epigenetics of Normal Pregnancy

Physical Activity during Pregnancy and Childhood Obesity: Systematic Review and Meta-Analysis

Background and Objectives: The repercussions of childhood overweight and obesity are multifaceted, extending beyond the realm of physiology and giving rise to psychological and emotional disturbances in affected children. The precise effects of gestational physical activity (PA) on parameters related to childhood overweight and obesity remain inadequately understood. The aim of this study (Registration CRD42022372490) was to evaluate the literature regarding the influence of PA during pregnancy on the risk of childhood overweight and obesity. Materials and Methods: Only randomized controlled trials (RCTs) were considered for inclusion. Determinant parameters of childhood obesity were analyzed. A total of 30 studies involving 16,137 pregnant women were examined. Five meta-analyses about the effects of PA during pregnancy on determinants of childhood overweight and obesity were conducted. Results: Although favorable trends were observed, Meta-Analyses showed no statistical differences in the effects of PA on weight at birth (Z = 0.03, p = 0.97), Ponderal Index at birth (Z = 0.64, p = 0.52), Macrosomia and Large for Gestational Age at birth (Z = 0.93, p = 0.35), children's BMI (Z = 0.78, p = 0.44), weight (Z = 0.50, p = 0.62), and skinfold thicknesses (Z = 0.45, p = 0.65). Conclusions: The engagement in physical activity during pregnancy exhibits a favorable trend in parameters associated with childhood overweight and obesity while presenting no adverse effects on such outcomes.

The role of prenatal maternal sex steroid hormones in weight and adiposity at birth and growth trajectories during infancy

Objective

Intrauterine factors can impact fetal and child growth and may underlie the developmental origins of childhood obesity. Sex steroid hormone exposure during pregnancy is a plausible target because of the impact on placental vascularization, nutrient transportation, bone growth, adipogenesis, and epigenetic modifications. In this study we assessed maternal sex steroid hormones in each trimester in relation to birthweight, neonatal adiposity, and infant growth trajectories, and evaluate sensitive windows of development.

Methods

Participants from a prospective pregnancy cohort who delivered at term were included in the analysis (n=252). Estrone, estradiol, and estriol, as well as total and free testosterone throughout gestation were assessed using high-performance liquid chromatography and tandem mass spectrometry. Path analyses were used to assess the direct associations of sex steroid hormones in each trimester with birth outcomes and infant growth trajectories (birth to 12 months) adjusting for covariates and considering moderation by sex.

Results

The associations between prenatal sex steroid hormones and fetal/infant growth varied by sex and hormone assessment timing. First trimester estrone were associated with higher birthweight z-scores (β=0.37, 95%CI: 0.02, 0.73) and truncal skinfold thickness (TST) at birth (β=0.94, 95%CI: 0.34, 1.54) in female infants. Third trimester total testosterone was associated with higher TST at birth (β=0.61, 95%CI: 0.02, 1.21) in male infants. First trimester estrone/estradiol and first and third trimesters testosterone were associated with lower probabilities of high stable weight trajectory compared to low stable weight trajectory (Estrone: β=-3.87, 95%CI: -6.59, -1.16; First trimester testosterone: β=-3.53, 95%CI: -6.63, -0.43; Third trimester testosterone: β=-3.67, 95%CI: -6.66, -0.69) during infancy in male infants.

Conclusions

We observed associations between prenatal sex steroid hormone exposure and birthweight, neonatal adiposity and infant growth that were sex and gestational timing dependent. Our findings suggest further investigation on additional mechanisms linking prenatal sex steroid exposure and fetal/postnatal growth is needed.

Exploring the role of exosomal MicroRNAs as potential biomarkers in preeclampsia

The complex pathogenesis of preeclampsia (PE), a significant contributor to maternal and neonatal mortality globally, is poorly understood despite substantial research. This review explores the involvement of exosomal microRNAs (exomiRs) in PE, focusing on their impact on the protein kinase B (AKT)/hypoxia-inducible factor 1-α (HIF1α)/vascular endothelial growth factor (VEGF) signaling pathway as well as endothelial cell proliferation and migration. Specifically, this article amalgamates existing evidence to reveal the pivotal role of exomiRs in regulating mesenchymal stem cell and trophoblast function, placental angiogenesis, the renin-angiotensin system, and nitric oxide production, which may contribute to PE etiology. This review emphasizes the limited knowledge regarding the role of exomiRs in PE while underscoring the potential of exomiRs as non-invasive biomarkers for PE diagnosis, prediction, and treatment. Further, it provides valuable insights into the mechanisms of PE, highlighting exomiRs as key players with clinical implications, warranting further exploration to enhance the current understanding and the development of novel therapeutic interventions.

Influence of Physical Activity during Pregnancy on Maternal Hypertensive Disorders: A Systematic Review and Meta-Analysis of Randomized Controlled Trials

Gestational hypertension is a notable concern with ramifications for maternal and fetal health. Preemptive measures, including physical activity (PA), are crucial. There is a pressing need for comprehensive investigations into the impact of various forms of PA on hypertensive disorders. A systematic review and meta-analysis (CRD42022372468) following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines was performed. Our review exclusively considered randomized clinical trials (RCTs) between 2010 and 2023, using the following databases: EBSCO, including Academic Search Premier, Education Resources Information Center, PubMed/MEDLINE, SPORTDiscus, and OpenDissertations; Clinicaltrials.gov; Web of Science; Scopus; the Cochrane Database of Systematic Reviews; and the Physiotherapy Evidence Database (PEDro). The primary outcome was hypertensive disorders occurring during pregnancy (14 studies). Diagnosed preeclampsia (15 studies) and blood pressure levels were also examined (17 studies). PA during pregnancy was significantly associated with a reduced risk of hypertensive disorders (RR = 0.44, 95% CI = 0.30, 0.66). The data also indicate a positive correlation between PA during pregnancy and both systolic (MD = -2.64, 95% CI = -4.79, -0.49) and diastolic (MD = -1.99, 95% CI = -3.68, -0.29) blood pressure levels. The relationship between PA and the incidence of diagnosed preeclampsia did not demonstrate a statistically significant association (RR = 0.81, 95% CI = 0.59, 1.11; p = 0.20). Random effects were used for all analyses. PA during pregnancy promises to improve maternal health by reducing the risk of gestational hypertension and positively affecting systolic and diastolic blood pressure.

Epigenetics and Pregnancy: Conditional Snapshot or Rolling Event

Epigenetics modification such as DNA methylation can affect maternal health during the gestation period. Furthermore, pregnancy can drive a range of physiological and molecular changes that have the potential to contribute to pathological conditions. Pregnancy-related risk factors include multiple environmental, behavioral, and hereditary factors that can impact maternal DNA methylation with long-lasting consequences. Identification of the epigenetic patterns linked to poor pregnancy outcomes is crucial since changes in DNA methylation patterns can have long-term effects. In this review, we provide an overview of the epigenetic changes that influence pregnancy-related molecular programming such as gestational diabetes, immune response, and pre-eclampsia, in an effort to close the gap in current understanding regarding interactions between the environment, the genetics of the fetus, and the pregnant woman.

Epigenetics of pregnancy: looking beyond the DNA code

Epigenetics is the branch of genetics that studies the different mechanisms that influence gene expression without direct modification of the DNA sequence. An ever-increasing amount of evidence suggests that such regulatory processes may play a pivotal role both in the initiation of pregnancy and in the later processes of embryonic and fetal development, thus determining long-term effects even in adult life. In this narrative review, we summarize the current knowledge on the role of epigenetics in pregnancy, from its most studied and well-known mechanisms to the new frontiers of epigenetic regulation, such as the role of ncRNAs and the effects of the gestational environment on fetal brain development. Epigenetic mechanisms in pregnancy are a dynamic phenomenon that responds both to maternal-fetal and environmental factors, which can influence and modify the embryo-fetal development during the various gestational phases. Therefore, we also recapitulate the effects of the most notable environmental factors that can affect pregnancy and prenatal development, such as maternal nutrition, stress hormones, microbiome, and teratogens, focusing on their ability to cause epigenetic modifications in the gestational environment and ultimately in the fetus. Despite the promising advancements in the knowledge of epigenetics in pregnancy, more experience and data on this topic are still needed. A better understanding of epigenetic regulation in pregnancy could in fact prove valuable towards a better management of both physiological pregnancies and assisted reproduction treatments, other than allowing to better comprehend the origin of multifactorial pathological conditions such as neurodevelopmental disorders.

An exercise program throughout pregnancy: Barakat model

The physiologic processes of pregnancy and childbirth can determine the future well-being of mothers and children due to the great quantity and quality of modifications that these processes require in all areas of the female body and fetus. Recent evidence has confirmed that modern unhealthy lifestyles negatively affect pregnancy outcomes. Engaging in unhealthy habits during pregnancy increases the risk of chronic disease in both the mother and the fetus. Regarding physical exercise during pregnancy, throughout history, many professionals and scientists have reported the best gestational conditions for the mother, fetus, and newborn. The perspectives and advice have changed over time, including periods of strong conservatism. This history has affected the recommendations for the type and amount of exercise that a healthy woman should perform during pregnancy. The aim of this article is to determine the basic aspects that physical exercise programs during pregnancy should define in the near future. Additionally, from the results of this article, we propose an exercise program model that includes many exercises spanning throughout pregnancy (3 blocks = until 20 weeks, until 30 weeks and until the end of the pregnancy). An exercise session model divided into seven parts and recommendations of operative position to exercise during pregnancy are also provided.

Role of metformin in epigenetic regulation of placental mitochondrial biogenesis in maternal diabetes

Adverse maternal environments, such as diabetes and obesity, impair placental mitochondrial function, which affects fetal development and offspring long-term health. The underlying mechanisms and effective interventions to abrogate such effect remain unclear. Our previous studies demonstrated impaired mitochondrial biogenesis in male human placenta of diabetic mothers. In the present studies, epigenetic marks possibly related to mitochondrial biogenesis in placentae of women with diabetes (n = 23) and controls (n = 23) were analyzed. Effects of metformin were examined in human placental explants from a subgroup of diabetic women and in a mouse model of maternal high fat diet feeding. We found that maternal diabetes was associated with epigenetic regulation of mitochondrial biogenesis in human placenta in a fetal sex-dependent manner, including decreased histone acetylation (H3K27 acetylation) and increased promoter methylation of peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PGC-1α). In male placenta, the levels of H3K27 acetylation and PGC-1α promoter methylation correlated significantly with the activity of AMP-activated protein kinase (AMPK). Metformin treatment on male diabetic placental explant activated AMPK and stimulated PGC-1α expression, concomitant with increased H3K27 acetylation and decreased PGC-1α promoter methylation. In vivo, we show that maternal metformin treatment along with maternal high fat diet significantly increased mouse placental abundance of PGC-1α expression and downstream mitochondrial transcription factor A (TFAM) and inhibited maternal high fat diet-impaired placental efficiency and glucose tolerance in offspring. Together, these findings suggest the capability of metformin to stimulate placental mitochondrial biogenesis and inhibit the aberrant epigenetic alterations occurring in maternal diabetes during pregnancy, conferring protective effects on offspring.

Effect of imbalance in folate and vitamin B12 in maternal/parental diet on global methylation and regulatory miRNAs

DNA methylation, a central component of the epigenetic network is altered in response to nutritional influences. In one-carbon cycle, folate acts as a one-carbon carrier and vitamin B12 acts as co-factor for the enzyme methionine synthase. Both folate and vitamin B12 are the important regulators of DNA methylation which play an important role in development in early life. Previous studies carried out in this regard have shown the individual effects of these vitamins but recently the focus has been to study the combined effects of both the vitamins during pregnancy. Therefore, this study was planned to elucidate the effect of the altered dietary ratio of folate and B12 on the expression of transporters, related miRNAs and DNA methylation in C57BL/6 mice. Female mice were fed diets with 9 combinations of folate and B12 for 4 weeks. They were mated and off-springs born (F1) were continued on the same diet for 6 weeks post-weaning. Maternal and fetal (F2) tissues were collected at day 20 of gestation. Deficient state of folate led to an increase in the expression of folate transporters in both F1 and F2 generations, however, B12 deficiency (BDFN) also led to an increase in the expression in both the generations. B12 transporters/proteins were found to be increased with B12 deficiency in F1 and F2 generations except for TC-II in the kidney which was found to be decreased in the F1 generation. miR-483 was found to be increased with all conditions of folate and B12 in both F1 and F2 generations, however, deficient conditions of B12 led to an increase in the expression of miR-221 in both F1 and F2 generations. The level of miR-133 was found to be increased in BDFN group in F1 generation however; in F2 generation the change in expression was tissue and sex-specific. Global DNA methylation was decreased with deficiency of both folate and B12 in maternal tissues (F1) but increased with folate deficiency in placenta (F1) and under all conditions in fetal tissues (F2). DNA methyltransferases were overall found to be increased with deficiency of folate and B12 in both F1 and F2 generations. Results suggest that the dietary ratio of folate and B12 resulted in altered expression of transporters, miRNAs, and genomic DNA methylation in association with DNMTs.

Epigenetics and human reproduction: the primary prevention of the noncommunicable diseases

Epigenetic regulation of gene expression plays a key role in affecting human health and diseases with particular regard to human reproduction. The major concern in this field is represented by the epigenetic modifications in the embryo and the increased risk of long-life disorders induced by the use of assisted reproduction techniques, able to affect the epigenetic assessment in the first steps of embryo development. In this review, we analyze the correlation between epigenetic modifications and human reproduction, suggesting that the reversibility of the epigenetic processes could represent a novel resource for the treatment of the couple's infertility and that parental lifestyle in periconceptional period could be considered as an important issue of primary prevention.

DNA Methylation Inhibitor 5-Aza-2'-Deoxycytidine Modulates Endometrial Receptivity Through Upregulating HOXA10 Expression

Endometrial receptivity is a critical factor for embryo implantation. A decrease in endometrial homeobox A10 (HOXA10) expression is associated with hypermethylation of its promoter and lower endometrial receptivity in animals and humans. 5-Aza-2'-deoxycytidine (AZA) is a DNA methyltransferase inhibitor. However, whether demethylation of the HOXA10 gene could increase the receptivity of the human endometrium remains unknown. Homeobox A10 promoter methylation was analyzed using bisulfite genomic sequencing polymerase chain reaction. Quantitative real time polymerase chain reaction and Western blotting were used to analyze the expression of HOXA10 and its downstream target genes (integrin subunit β 3 [ITGB3] and insulin growth factor binding protein 1 [IGFBP1]) in Ishikawa cells treated with or without AZA for 24 hours. Their protein expression was analyzed with or without HOXA10 siRNA treatment. The effect of AZA on embryo implantation was examined using a Jeg-3 spheroid-endometrial cell attachment assay. The percentage of methylated CpG islands in the HOXA10 promoter was 72.0% without AZA treatment. However, it was 38% and 35% in the 1 and 10 μM AZA treatment groups, respectively. 5-Aza-2'-deoxycytidine strongly induced the expression of HOXA10, ITGB3, and IGFBP1 messenger RNA and their protein expression. Homeobox A10 knockdown led to decreased expression of HOXA10, ITGB3, and IGFBP1, with or without AZA treatment. The attachment rate of Jeg-3 spheroids increased significantly from 82% (control) to 95% (AZA 1 μM) and 96% (AZA 10 μM) after AZA treatment. 5-Aza-2'-deoxycytidine could upregulate the expression of ITGB3 and IGFBP1 via HOXA10 upregulation, and upregulation of ITGB3 and IGFBP1 plays an important role in endometrial receptivity during implantation. 5-Aza-2'-deoxycytidine may improve endometrial receptivity by upregulating the expression of HOXA10.

How The Genome Got a Life Span

In the space of little more than a decade, ideas of the human genome have shifted significantly, with the emergence of the notion that the genome an individual changes with development, age, disease, environmental inputs, and time. This paper examines the emergence of the genome with a life span, one that experiences drift, instability and mutability, and a host of other temporal changes. We argue that developments in chromatin biology have provided the basis for this genomic embodiment of experience and exposure. We analyze how time has come to matter for the genome through chromatin, providing analysis of examples in which the human life course is being explored as a set of material changes to chromatin. A genome with a lifespan aligns the molecular and the experiential in new ways, shifting ideas of life stages, their interrelation, and the temporality of health and disease.