Maternal DNA Methylation Research Articles

Maternal Blood Cadmium Concentrations and Whole Blood DNA Methylation during Pregnancy in the Early Autism Risk Longitudinal Investigation (EARLI)

Background: During pregnancy, the maternal epigenome may be responsive to environmental exposures. We tested whether maternal exposure to cadmium (Cd) results in differential maternal whole blood DNA methylation (DNAm) in early pregnancy.Methods: Maternal blood samples were collected at the initial study visit (during trimesters one or two of pregnancy) from 232 participants in the Early Autism Risk Longitudinal Investigation (EARLI) pregnancy cohort. We measured maternal blood Cd (n=215) using inductively coupled plasma mass spectrometry, which reflects recent exposure (blood t1/2 ~75 days), and measured maternal blood DNAm (n=201) on the Illumina 450K array; 93 non-smoking women had both measures available for analysis. Linear regression was used to test for site-specific associations between blood Cd and DNAm, adjusting for cell type composition and confounding variables.Results: The distribution of blood Cd was right skewed and log-transformed for statistical analyses. The geometric mean of blood Cd was 0.2 μg/L (Interquartile range = 0.13 μg/L). An interquartile range difference in blood Cd was associated with a 13.1% increase in B-cell proportions (95% CI: 1.0 – 25.2). In multivariable regression, six CpG sites were associated (p-value<10-5) with log blood Cd concentrations. At five of these sites, increasing blood Cd was associated with hypermethylation, and three corresponded to the genes LYN, TESC, and ESD. The CpG site near LYN was closest to genome-wide significance (p-value = 1.9x10-6), and an interquartile range difference in blood Cd was associated with an 8.4% increase in percent methylation at this site (95% CI: 5.1 – 11.6).Conclusion: We report site-specific associations between DNAm and blood Cd in early pregnancy. Future work will consider the persistence of DNAm marks. Identified sites may be potential biomarkers of Cd exposure that can inform future epidemiological studies or implicate downstream gene pathways affected by Cd exposure.

Dietary Unsaturated Fatty Acids Modulate Maternal Dyslipidemia-Induced DNA Methylation and Histone Acetylation in Placenta and Fetal Liver in Rats.

The present study assessed the role of dietary unsaturated fatty acids in maternal dyslipidemia-induced DNA methylation and histone acetylation in placenta and fetal liver and accumulation of lipids in the fetal liver. Weanling female Wistar rats were fed control and experimental diets for 2 months, mated, and continued on their diets during pregnancy. At gestation days of 18-20, rats were euthanized to isolate placenta and fetal liver. DNA methylation, DNA methyl transferase-1 (DNMT1) activity, acetylation of histones (H2A and H2B), and histone acyl transferase (HAT) activity were evaluated in placenta and fetal liver. Fetal liver lipid accumulation and activation of peroxisome proliferator-activated receptor-α (PPAR-α) were assessed. Maternal dyslipidemia caused significant epigenetic changes in placenta and fetal liver. In the placenta, (1) global DNA methylation increased by 37% and DNMT1 activity by 86%, (2) acetylated H2A and H2B levels decreased by 46% and 24% respectively, and (3) HAT activity decreased by 39%. In fetal liver, (1) global DNA methylation increased by 52% and DNMT1 activity by 78%, (2) acetylated H2A and H2B levels decreased by 28% and 26% respectively, and (3) HAT activity decreased by 37%. Maternal dyslipidemia caused a 4.75-fold increase in fetal liver triacylglycerol accumulation with a 78% decrease in DNA-binding ability of PPAR-α. Incorporation of dietary unsaturated fatty acids in the maternal high-fat diet significantly (p < 0.05) modulated dyslipidemia-induced effects in placenta and fetal liver. Eicosapentaenoic acid (EPA, 20:5n-3) + docosahexaenoic acid (DHA, 22:6n-3) exhibited a profound effect followed by alpha-linolenic acid (ALA, 18:3n-3) than linoleic acid (LNA, 18:2n-6) in modulating the epigenetic parameters in placenta and fetal liver.

Effects of Maternal Vitamin D Supplementation on the Maternal and Infant Epigenome.

Mothers and infants are at high risk for inadequate vitamin D status. Mechanisms by which vitamin D may affect maternal and infant DNA methylation are poorly understood. This study quantified the effects of vitamin D3 supplementation on DNA methylation in pregnant and lactating women and their breastfed infants. In this randomized controlled pilot study, pregnant women received vitamin D3 400 international units (IU) (n = 6; control) or 3,800 IU (n = 7; intervention) daily from late second trimester through 4-6 weeks postpartum. Epigenome-wide DNA methylation was quantified in leukocytes collected from mothers at birth and mother-infant dyads at 4-6 weeks postpartum. At birth, intervention group mothers showed DNA methylation gain and loss at 76 and 89 cytosine-guanine (CpG) dinucleotides, respectively, compared to controls. Postpartum, methylation gain was noted at 200 and loss at 102 CpGs. Associated gene clusters showed strongest biologic relevance for cell migration/motility and cellular membrane function at birth and cadherin signaling and immune function at postpartum. Breastfed 4-6-week-old infants of intervention mothers showed DNA methylation gain and loss in 217 and 213 CpGs, respectively, compared to controls. Genes showing differential methylation mapped most strongly to collagen metabolic processes and regulation of apoptosis. Maternal vitamin D supplementation during pregnancy and lactation alters DNA methylation in mothers and breastfed infants. Additional work is needed to fully elucidate the short- and long-term biologic effects of vitamin D supplementation at varying doses, which could hold important implications for establishing clinical recommendations for prenatal and offspring health promotion.

Effects of Cadmium Exposure on DNA Methylation at Imprinting Control Regions and Genome-Wide in Mothers and Newborn Children.

Background:Imprinted genes are defined by their preferential expression from one of the two parental alleles. This unique mode of gene expression is dependent on allele-specific DNA methylation profiles established at regulatory sequences called imprinting control regions (ICRs). These loci have been used as biosensors to study how environmental exposures affect methylation and transcription. However, a critical unanswered question is whether they are more, less, or equally sensitive to environmental stressors as the rest of the genome.Objectives:Using cadmium exposure in humans as a model, we aimed to determine the relative sensitivity of ICRs to perturbation of methylation compared to similar, nonimprinted loci in the genome.Methods:We assayed DNA methylation genome-wide using bisulfite sequencing of 19 newborn cord blood and 20 maternal blood samples selected on the basis of maternal blood cadmium levels. Differentially methylated regions (DMRs) associated with cadmium exposure were identified.Results:In newborn cord blood and maternal blood, 641 and 1,945 cadmium-associated DMRs were identified, respectively. DMRs were more common at the 15 maternally methylated ICRs than at similar nonimprinted loci in newborn cord blood () and maternal blood (), suggesting a higher sensitivity for ICRs to cadmium. Genome-wide, Enrichr analysis indicated that the top three functional categories for genes that overlapped DMRs in maternal blood were body mass index (BMI) (), blood pressure (), and body weight (). In newborn cord blood, the top three functional categories were BMI, atrial fibrillation, and hypertension, although associations were not significant after correction for multiple testing (). These findings suggest that epigenetic changes may contribute to the etiology of cadmium-associated diseases.Conclusions:We analyzed cord blood and maternal blood DNA methylation profiles genome-wide at nucleotide resolution in individuals selected for high and low blood cadmium levels in the first trimester. Our findings suggest that ICRs may be hot spots for perturbation by cadmium, motivating further study of these loci to investigate potential mechanisms of cadmium action. https://doi.org/10.1289/EHP2085

Genome-wide DNA methylation associations with spontaneous preterm birth in US blacks: findings in maternal and cord blood samples

ABSTRACTPreterm birth (PTB) affects one in six Black babies in the United States. Epigenetics is believed to play a role in PTB; however, only a limited number of epigenetic studies of PTB have been reported, most of which have focused on cord blood DNA methylation (DNAm) and/or were conducted in white populations. Here we conducted, by far, the largest epigenome-wide DNAm analysis in 300 Black women who delivered early spontaneous preterm (sPTB, n = 150) or full-term babies (n = 150) and replicated the findings in an independent set of Black mother-newborn pairs from the Boston Birth Cohort. DNAm in maternal blood and/or cord blood was measured using the Illumina HumanMethylation450 BeadChip. We identified 45 DNAm loci in maternal blood associated with early sPTB, with a false discovery rate (FDR) <5%. Replication analyses confirmed sPTB associations for cg03915055 and cg06804705, located in the promoter regions of the CYTIP and LINC00114 genes, respectively. Both loci had comparable associations with early sPTB and early medically-indicated PTB, but attenuated associations with late sPTB. These associations could not be explained by cell composition, gestational complications, and/or nearby maternal genetic variants. Analyses in the newborns of the 110 Black women showed that cord blood methylation levels at both loci had no associations with PTB. The findings from this study underscore the role of maternal DNAm in PTB risk, and provide a set of maternal loci that may serve as biomarkers for PTB. Longitudinal studies are needed to clarify temporal relationships between maternal DNAm and PTB risk.

Maternal prenatal stress and infant DNA methylation: A systematic review.

Maternal prenatal stress has been linked to a variety of infant postnatal outcomes, partially through alterations in fetal HPA axis functioning; yet the underlying pathobiology remains elusive. Current literature posits DNA methylation as a candidate mechanism through which maternal prenatal stress can influence fetal HPA axis functioning. The goal of this systematic review was to summarize the literature examining the associations among maternal prenatal stress, DNA methylation of commonly studied HPA axis candidate genes, and infant HPA axis functioning. Results from the review provided evidence for a link between various maternal prenatal stressors, NR3C1 methylation, and infant stress reactivity, but findings among other genes were limited, with mixed results. An original study quality review tool revealed that a majority of studies in the review are adequate, and emphasizes the need for future research to consider study quality when interpreting research findings.

Maternal low glycemic index dietary intervention and DNA methylation in 5 year old offspring: results from the ROLO Kids Study

Maternal low glycemic index dietary intervention and DNA methylation in 5 year old offspring: results from the ROLO Kids Study

Parenting stress and DNA methylation among African Americans in the InterGEN Study.

General life stress has been associated with altered DNA methylation in individuals of African Ancestry, although the relationship between parenting stress and DNA methylation has not been described. The purpose of this study was to examine the relationship between maternal parenting stress and DNA methylation among African Ancestry mother-child dyads. We evaluated epigenome-wide DNA methylation relative to parenting stress in 74 mother-child dyads using linear mixed models. Significant variation in maternal DNA methylation at 95 CpG sites was associated with level of parenting stress. Notably, we identified a change in DNA methylation associated with poly (ADP-ribose) polymerase-1, which plays a key role in stress signaling. We did not identify any significant variation in child DNA methylation related to maternal parenting stress. However, DNA methylation patterns observed in children mirrored patterns observed in their mothers. The results suggest that differential maternal DNA methylation is associated with higher levels of parenting stress.

Maternal gestational weight gain and DNA methylation in young women: application of life course mediation methods.

To investigate the role of maternal gestational weight gain (GWG) and prepregnancy BMI on programming offspring DNA methylation. Among 589 adult (age=32) women participants of the Jerusalem Perinatal Study, we quantified DNA methylation in five candidate genes. We used inverse probability-weighting and parametric g-formula to estimate direct effects of maternal prepregnancy BMI and GWG on methylation. Higher maternal GWG, but not prepregnancy BMI, was inversely related to offspring ABCA1 methylation (β= -1.1% per quartile; 95%CI: -2.0, -0.3) after accounting for ancestry, parental and offspring exposures. Total and controlled direct effects were nearly identical suggesting included offspring exposures did not mediate this relationship. Results were robust to sensitivity analyses for missing data and model specification. We find some support for epigenetic programming and highlight strengths and limitations of these methods relative to other prevailing approaches.

Maternal PCB exposure might affect not only maternal and foetal metabolome, but also maternal gut microbiome and foetal DNA methylation

Maternal PCB exposure might affect not only maternal and foetal metabolome, but also maternal gut microbiome and foetal DNA methylation

Maternal serum PFOA concentration and DNA methylation in cord blood: A pilot study

Perfluorooctanoic acid (PFOA), a perfluoroalkyl substance, is commonly detected in the serum of pregnant women and may impact fetal development via epigenetic re-programming. In a pilot study, we explored associations between serum PFOA concentrations during pregnancy and offspring peripheral leukocyte DNA methylation at delivery in women with high (n = 22, range: 12–26 ng/mL) and low (n = 22, range: 1.1–3.1 ng/mL) PFOA concentrations. After adjusting for cell type, child sex, and income, we did not find differences in CpG methylation in the two exposure groups that reached epigenome-wide significance. Among the 20 CpGs with the lowest p-values we found that seven CpG sites in three genes differed by exposure status. In a confirmatory cluster analysis, these 20 CpGs clustered into two groups that perfectly identified exposure status. Future studies with larger sample sizes should confirm these findings and determine if PFOA-associated changes in DNA methylation underlie potential health effects of PFOA.

Intergenerational transmission of well being–genetic and epigenetic mechanisms

IntroductionMaternal mental well being influences offspring development. Research suggests that an interplay between genetic and environmental factors underlies this familial transmission of mental disorders.ObjectivesTo explore an interaction between genetic and environmental factors to predict trajectories of maternal mental well being, and to examine whether these trajectories are associated with epigenetic modifications in mothers and their offspring.MethodWe assessed maternal childhood trauma and rearing experiences, prenatal and postnatal symptoms of depression and stress experience from 6 to 72 months postpartum, and genetic and epigenetic variation in a longitudinal birth-cohort study (n = 262) (Maternal adversity, vulnerability and neurodevelopment project). We used latent class modeling to describe trajectories in maternal depressive symptoms, parenting stress, marital stress and general stress, taking polygenetic risk for major depressive disorder (MDD), a composite score for maternal early life adversities, and prenatal depressive symptoms into account.ResultsGenetic risk for MDD associated with trajectories of maternal well being in the postpartum, conditional on the experience of early life adversities and prenatal symptoms of depression. We will explore whether these trajectories are also linked to DNA methylation patterns in mothers and their offspring. Preliminary analyses suggest that maternal early life adversities associate with offspring DNA methylation age estimates, which is mediated through maternal mental well being and maternal DNA methylation age estimates.ConclusionWe found relevant gene-environment interactions associated with trajectories of maternal well being. Our findings inform research on mechanisms underlying familial transmission of vulnerability for psychopathology and might thus be relevant to prevention and early intervention programs.Disclosure of interestThe authors have not supplied their declaration of competing interest.

Maternal DNA Methylation in Second Half of Pregnancy in Th1, Th2, Th17 and Treg Pathway Genes Differs with Birth-Order

Maternal DNA Methylation in Second Half of Pregnancy in Th1, Th2, Th17 and Treg Pathway Genes Differs with Birth-Order

Consistency and Variability of DNA Methylation in Women During Puberty, Young Adulthood, and Pregnancy.

Prior DNA methylation (DNA-m) analyses have identified cytosine-phosphate-guanine (CpG) sites, which show either a significant change or consistency during lifetime. However, the proportion of CpGs that are neither significantly different nor consistent over time (indifferent CpGs) is unknown. We investigated the methylation dynamics, both longitudinal changes and consistency, in women from preadolescence to late pregnancy using DNA-m of peripheral blood cells. Consistency of cell type–adjusted DNA-m between paired individuals was assessed by regressing CpGs of subsequent age on the prior, stability by intraclass correlation coefficients (>0.5), and changes by linear mixed models. In the first 2 transitions (10-18 years and 18 years to early pregnancy), 19.5% and 20.9% CpGs were consistent, but only 0.35% in the third transition (from early to late pregnancy). Significant changes in methylation were found in 0.7%, 5.6%, and 0% CpGs, respectively. Functional enrichment analyses of genes with significant changes in DNA-m in early pregnancy (5.6%) showed that the maternal DNA-m seems to reflect signaling pathways between the uterus and the trophoblast. The transition from early to late pregnancy showed low consistency/stability and no changes, suggesting the presence of a large proportion of indifferent CpGs in late pregnancy.

Lipid metabolism is associated with developmental epigenetic programming.

Maternal diet and metabolism impact fetal development. Epigenetic reprogramming facilitates fetal adaptation to these in utero cues. To determine if maternal metabolite levels impact infant DNA methylation globally and at growth and development genes, we followed a clinical birth cohort of 40 mother-infant dyads. Targeted metabolomics and quantitative DNA methylation were analyzed in 1st trimester maternal plasma (M1) and delivery maternal plasma (M2) as well as infant umbilical cord blood plasma (CB). We found very long chain fatty acids, medium chain acylcarnitines, and histidine were: (1) stable in maternal plasma from pregnancy to delivery, (2) significantly correlated between M1, M2, and CB, and (3) in the top 10% of maternal metabolites correlating with infant DNA methylation, suggesting maternal metabolites associated with infant DNA methylation are tightly controlled. Global DNA methylation was highly correlated across M1, M2, and CB. Thus, circulating maternal lipids are associated with developmental epigenetic programming, which in turn may impact lifelong health and disease risk. Further studies are required to determine the causal link between maternal plasma lipids and infant DNA methylation patterns.

Genetic contribution to variation in DNA methylation at maternal smoking-sensitive loci in exposed neonates

ABSTRACTEpigenome-wide DNA methylation association studies have identified highly replicable genomic loci sensitive to maternal smoking during gestation. The role of inter-individual genetic variation in influencing DNA methylation, leading to the possibility of confounding or bias of such associations, has not been assessed. We investigated whether the DNA methylation levels at the top 10 CpG sites previously associated with exposure to maternal smoking during gestation were associated with individual genetic variation at the genome-wide level. Genome-wide association tests between DNA methylation at the top 10 candidate CpG and genome-wide SNPs were performed in 736 case and control participants of the California Childhood Leukemia Study. Three of the strongest maternal-smoking sensitive CpG sites in newborns were significantly associated with SNPs located proximal to each gene: cg18146737 in the GFI1 gene with rs141819830 (P = 8.2×10−44), cg05575921 in the AHRR gene with rs148405299 (P = 5.3×10−10), and cg12803068 in the MYO1G gene with rs61087368 (P = 1.3×10−18). For the GFI1 CpG cg18146737, the underlying genetic variation at rs141819830 confounded the association between maternal smoking and DNA methylation in our data (the regression coefficient changed from −0.02 [P = 0.139] to −0.03 [P = 0.015] after including the genotype). Our results suggest that further studies using DNA methylation at cg18146737, cg05575921, or cg12803068 that aim to assess exposure to maternal smoking during gestation should include genotype at the corresponding SNP. New methods are required for adequate and routine inclusion of genotypic influence on DNA methylation in epigenome-wide association studies to control for potential confounding.

Maternal Methyl-Group Donor Intake and Global DNA (Hydroxy)Methylation before and during Pregnancy.

It is still unclear to which extent methyl-group intake during pregnancy can affect maternal global DNA (hydroxyl)methylation. Pregnancy methylation profiling and its link with methyl-group intake in a healthy population could enhance our understanding of the development of pregnancy related disorders. One hundred forty-eight women were enrolled in the MANOE (MAternal Nutrition and Offspring’s Epigenome) study. Thiry-four women were enrolled before pregnancy and 116 during the first trimester of pregnancy. Global DNA (hydroxy)methylation in blood using LC-MS/MS and dietary methyl-group intake (methionine, folate, betaine, and choline) using a food-frequency questionnaire were estimated pre-pregnancy, during each trimester, and at delivery. Global DNA (hydroxy)methylation levels were highest pre-pregnancy and at weeks 18–22 of pregnancy. We observed a positive relation between folic acid and global DNA methylation (p = 0.04) and hydroxymethylation (p = 0.04). A high intake of methionine pre-pregnancy and in the first trimester showed lower (hydroxy)methylation percentage in weeks 11–13 and weeks 18–22, respectively. Choline and betaine intake in the first weeks was negatively associated with hydroxymethylation. Women with a high intake of these three methyl groups in the second and third trimester showed higher hyrdoxymethylation/methylation levels in the third trimester. To conclude, a time trend in DNA (hydroxy)methylation was found and women with higher methyl-group intake showed higher methylation in the third trimester, and not in earlier phases of pregnancy.

Relationship between maternal environment and DNA methylation patterns of estrogen receptor alpha in wild Eastern Bluebird (Sialia sialis) nestlings: a pilot study.

There is mounting evidence that, across taxa, females breeding in competitive environments tend to allocate more testosterone to their offspring prenatally and these offspring typically have more aggressive and faster‐growing phenotypes. To date, no study has determined the mechanisms mediating this maternal effect's influence on offspring phenotype. However, levels of estrogen receptor alpha (ER α) gene expression are linked to differences in early growth and aggression; thus, maternal hormones may alter gene regulation, perhaps via DNA methylation, of ER α in offspring during prenatal development. We performed a pilot study to examine natural variation in testosterone allocation to offspring through egg yolks in wild Eastern Bluebirds (Sialia sialis) in varying breeding densities and percent DNA methylation of CG dinucleotides in the ER α promoter in offspring brain regions associated with growth and behavior. We hypothesized that breeding density would be positively correlated with yolk testosterone, and prenatal exposure to maternal‐derived yolk testosterone would be associated with greater offspring growth and decreased ER α promoter methylation. Yolk testosterone concentration was positively correlated with breeding density, nestling growth rate, and percent DNA methylation of one out of five investigated CpG sites (site 3) in the diencephalon ER α promoter, but none in the telencephalon (n = 10). Percent DNA methylation of diencephalon CpG site 3 was positively correlated with growth rate. These data suggest a possible role for epigenetics in mediating the effects of the maternal environment on offspring phenotype. Experimentally examining this mechanism with a larger sample size in future studies may help elucidate a prominent way in which animals respond to their environment. Further, by determining the mechanisms that mediate maternal effects, we can begin to understand the potential for the heritability of these mechanisms and the impact that maternal effects are capable of producing at an evolutionary scale.

Distress During Pregnancy: Epigenetic Regulation of Placenta Glucocorticoid-Related Genes and Fetal Neurobehavior.

Increased risk of psychopathology is observed in children exposed to maternal prenatal distress, and elevated maternal cortisol and epigenetic regulation of placental glucocorticoid-pathway genes are potential mechanisms. The authors examined maternal distress and salivary cortisol in relation to fetal movement and heart rate ("coupling") and DNA methylation of three glucocorticoid pathway genes-HSD11B2, NR3C1, and FKBP5-in term placentas. Mood questionnaires and salivary cortisol were collected from 61 women between 24-27 gestational weeks, and fetal assessment was conducted at 34-37 weeks. Placental CpG methylation in the three genes was analyzed using 450K Beadchips and bisulfite sequencing; correlations between maternal and fetal variables and DNA methylation were tested; and maternal distress effects on fetal behavior via DNA methylation were investigated. Perceived stress (Perceived Stress Scale), but not cortisol, was associated with altered CpG methylation in placentas. In the highest tertile of the Perceived Stress Scale, the Beadchip data revealed modestly elevated methylation of HSD11B2, associated with lower fetal coupling (β=-0.51), and modestly elevated methylation of FKBP5, also with lower fetal coupling (β=-0.47). These increases in methylation were validated by bisulfite sequencing, where they occurred in a minority of clones. This is the first study to link the effects of pregnant women's distress on the fetus and epigenetic changes in placental genes. Since increased DNA methylation in HSD11B2 and FKBP5 are seen in a minority of bisulfite sequencing clones, these epigenetic changes, and functional consequences, may affect subpopulations of placental cells.

The green tea polyphenol EGCG alleviates maternal diabetes–induced neural tube defects by inhibiting DNA hypermethylation

Maternal diabetes increases the risk of neural tube defects in offspring. Our previous study demonstrated that the green tea polyphenol, Epigallocatechin gallate, inhibits high glucose-induced neural tube defects in cultured embryos. However, the therapeutic effect of Epigallocatechin gallate on maternal diabetes-induced neural tube defects is still unclear. We aimed to examine whether Epigallocatechin gallate treatment can reduce maternal diabetes-induced DNA methylation and neural tube defects. Nondiabetic and diabetic pregnant mice at embryonic day 5.5 were given drinking water with or without 1 or 10 μM Epigallocatechin gallate. At embryonic day 8.75, embryos were dissected from the visceral yolk sac for the measurement of the levels and activity of DNA methyltransferases, the levels of global DNA methylation, and methylation in the CpG islands of neural tube closure essential gene promoters. embryonic day 10.5 embryos were examined for neural tube defect incidence. Epigallocatechin gallate treatment did not affect embryonic development because embryos from nondiabetic dams treated with Epigallocatechin gallate did not exhibit any neural tube defects. Treatment with 1 μM Epigallocatechin gallate did not reduce maternal diabetes-induced neural tube defects significantly. Embryos from diabetic dams treated with 10 μM Epigallocatechin gallate had a significantly lower neural tube defect incidence compared with that of embryos without Epigallocatechin gallate treatment. Epigallocatechin gallate reduced neural tube defect rates from 29.5% to 2%, an incidence that is comparable with that of embryos from nondiabetic dams. Ten micromoles of Epigallocatechin gallate treatment blocked maternal diabetes-increased DNA methyltransferases 3a and 3b expression and their activities, leading to the suppression of global DNA hypermethylation. Additionally, 10 μM Epigallocatechin gallate abrogated maternal diabetes-increased DNA methylation in the CpG islands of neural tube closure essential genes, including Grhl3, Pax3, and Tulp3. Epigallocatechin gallate reduces maternal diabetes-induced neural tube defects formation and blocks the enhanced expression and activity of DNA methyltransferases, leading to the suppression of DNA hypermethylation and the restoration of neural tube closure essential gene expression. These observations suggest that Epigallocatechin gallate supplements could mitigate the teratogenic effects of hyperglycemia on the developing embryo and prevent diabetes-induced neural tube defects.