In utero physiology: role of folic acid in nutrient delivery and fetal development

Placenta-Related Parameters at Delivery in Relation to Folic Acid Supplementation in Different Pregnancies

Folic acid plays an important role in the synthesis, repair, and methylation of deoxyribonucleic acid (DNA). Currently, most studies have focused on the effects of periconceptional folic acid (FA) supplementation on fetal development, and there is still a lack of population-based research exploring the association between FA use during pregnancy and placental development. This study aimed to investigate the impacts of FA supplementation in different pregnancies on placenta-related parameters at delivery. The study included 2708 pregnant women recruited from Ma'anshan City, Anhui Province, China, between May 2013 and September 2014. Information on FA use from one month before conception to delivery was collected. Placental length, width, and thickness were measured. Multivariable logistic regression analysis was used to assess the effects of FA supplementation in different pregnancies on placenta-related parameters. Based on multiple regression analysis, propensity score weighting was adopted to enhance comparability between different FA supplementation groups. Compared with FA non-users, FA supplementation before conception was associated with increased placental width (0.241 cm, 95%CI: 0.052-0.429, p = 0.013) and increased placental surface area (6.398 cm2, 95%CI: 1.407-11.389, p = 0.012), and FA use in early/middle pregnancy was, respectively, related with increased placental thickness (0.061 cm, 95%CI: 0.004-0.117, p = 0.036; 0.066 cm, 95%CI: 0.004-0.129, p = 0.038). FA use before conception could increase placental width and area, and FA use in early/middle pregnancy could increase placental thickness. To confirm the findings, further investigations are needed.

Associations of prenatal one-carbon metabolism nutrients and metals with epigenetic aging biomarkers at birth and in childhood in a US cohort

Epigenetic gestational age acceleration (EGAA) at birth and epigenetic age acceleration (EAA) in childhood may be biomarkers of the intrauterine environment. We investigated the extent to which first-trimester folate, B12, 5 essential, and 7 non-essential metals in maternal circulation are associated with EGAA and EAA in early life. Bohlin EGAA and Horvath pan-tissue and skin and blood EAA were calculated using DNA methylation measured in cord blood (N=351) and mid-childhood blood (N=326; median age = 7.7 years) in the Project Viva pre-birth cohort. A one standard deviation increase in individual essential metals (copper, manganese, and zinc) was associated with 0.94-1.2 weeks lower Horvath EAA at birth, and patterns of exposures identified by exploratory factor analysis suggested that a common source of essential metals was associated with Horvath EAA. We also observed evidence nonlinear associations of zinc with Bohlin EGAA, magnesium and lead with Horvath EAA, and cesium with skin and blood EAA at birth. Overall, associations at birth did not persist in mid-childhood; however, arsenic was associated with greater EAA at birth and in childhood. Prenatal metals, including essential metals and arsenic, are associated with epigenetic aging in early life, which might be associated with future health.

Intergenerational association of gut microbiota and metabolism with perinatal folate metabolism and neural tube defects

Disorders of folic acid metabolism during pregnancy lead to fetal neural tube defects (NTDs). However, the mechanisms still require further investigation. Here, we aim to analyze the brain metabolic profiles of 30 NTDs and 30 healthy fetuses. Our results indicated that low-folate diet during early life played a causal role in cerebral metabolism, especially in lipometabolic disturbance, highlighting the importance of folate in modulating brain development and metabolism. Next, we established a mouse model of NTDs. Interestingly, the differential metabolites are mainly involved in glycerophospholipid metabolism and biosynthesis of unsaturated fatty acids both in human and mice fetal brain. Since intestinal microbes could critically regulate neurofunction via the intestinal-brain axis, we further found the abundances of Firmicutes and Bacteroidetes in the gut of pregnant mice were correlated with the abundances of lipid metabolism related metabolites in the fetal brain. This finding probably reflects the intergenerational microbial-metabolism biomarkers of NTDs.

Folate deficiency among women of reproductive age in Ethiopia: A systematic review and meta-analysis

BACKGROUND

Folate deficiency (FD) can cause adverse health outcomes of public health significance. Although FD is a significant micronutrient deficiency in Ethiopia, concrete evidence is limited. Therefore, this systematic review and meta-analysis was designed to estimate the pooled prevalence of FD among women of reproductive age (WRA).

METHODS

A systematic literature search was performed using MEDLINE, Embase, CINAHL, Google Scholar, African Journals Online (AJOL), The Vitamin and Mineral Nutrition Information System (VMNIS) of the World Health Organization (WHO), Global Health Data Exchange (GHDx), and institutional repositories of major universities and research centers. Additionally, we scanned the reference lists of relevant articles. Two authors independently selected the studies, extracted the data, and the study risk of bias. Heterogeneity was assessed using the I2 statistic. We used a random-effects model to estimate the pooled mean serum/plasma folate and the pooled prevalence of FD. Begg's and Egger's tests were used to check publication bias.

RESULTS

Ten studies-nine cross-sectional and one case-control-with a total of 5,623 WRA were included in the systematic review and meta-analysis. Four (WRA = 1,619) and eight (WRA = 5,196) cross-sectional studies were used to estimate the pooled mean serum/plasma folate and prevalence of FD, respectively. The pooled mean serum/plasma folate concentration estimate was 7.14 ng/ml (95% CI: 5.73, 8.54), and the pooled prevalence of FD was estimated to be 20.80% (95% CI: 11.29, 32.27). In addition the meta-regression analysis showed that the sampling technique was significantly associated with mean serum/plasma folate concentration.

CONCLUSIONS

FD is a significant public health issue among WRA in Ethiopia. Therefore, the public health strategies of the country should focus on promoting the consumption of folate-rich foods, strengthening the coverage of folic acid supplementation and its adherence, and swift translation of the mandatory folic acid fortification into action.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO 2022-CRD42022306266.

Exposure to environmental contaminants and folic acid supplementation intergenerationally impact fetal skeleton development through the paternal lineage in a rat model

Persistent organic pollutants (POPs) are ubiquitous in the environment, which is of concern since they are broadly toxic for wildlife and human health. It is generally accepted that maternal prenatal folic acid supplementation (FA) may beneficially impact offspring development, but it has been recently shown that the father's exposures also influence the health of his offspring. Bone is an endocrine organ essential for whole-body homeostasis and is susceptible to toxicants. Herein, we tested the hypotheses that prenatal paternal exposure to POPs induces developmental bone disorders in fetuses across multiple generations and that FA supplementation attenuates these disorders. We used a four-generation rat model, in which F0 founder females were divided into four treatment groups. F0 females were gavaged with corn oil or an environmentally-relevant POPs mixture and fed either a control diet (2 mg FA/kg), or FA supplemented diet (6 mg FA/kg) before mating and until parturition (four treatments in total). After the birth of the F1 litters, all F0 females and subsequent generations received the FA control diet. Staining with alcian blue and alizarin red S of male and female fetal skeletons was performed at Gestational Day 19.5. Paternal direct and ancestral exposure to POPs delayed bone ossification and decreased the length of long limb bones in fetuses. Maternal FA supplementation did not counteract the POPs-associated delayed fetal ossification and reduced long bone length. In conclusion, prenatal paternal POPs exposure causes developmental bone abnormalities over multiple generations, which were not corrected by maternal FA supplementation.

High Folate, Perturbed One-Carbon Metabolism and Gestational Diabetes Mellitus

Folate is a dietary micronutrient essential to one-carbon metabolism. The World Health Organisation recommends folic acid (FA) supplementation pre-conception and in early pregnancy to reduce the risk of fetal neural tube defects (NTDs). Subsequently, many countries (~92) have mandatory FA fortification policies, as well as recommendations for periconceptional FA supplementation. Mandatory fortification initiatives have been largely successful in reducing the incidence of NTDs. However, humans have limited capacity to incorporate FA into the one-carbon metabolic pathway, resulting in the increasingly ubiquitous presence of circulating unmetabolised folic acid (uFA). Excess FA intake has emerged as a risk factor in gestational diabetes mellitus (GDM). Several other one-carbon metabolism components (vitamin B12, homocysteine and choline-derived betaine) are also closely entwined with GDM risk, suggesting a role for one-carbon metabolism in GDM pathogenesis. There is growing evidence from in vitro and animal studies suggesting a role for excess FA in dysregulation of one-carbon metabolism. Specifically, high levels of FA reduce methylenetetrahydrofolate reductase (MTHFR) activity, dysregulate the balance of thymidylate synthase (TS) and methionine synthase (MTR) activity, and elevate homocysteine. High homocysteine is associated with increased oxidative stress and trophoblast apoptosis and reduced human chorionic gonadotrophin (hCG) secretion and pancreatic β-cell function. While the relationship between high FA, perturbed one-carbon metabolism and GDM pathogenesis is not yet fully understood, here we summarise the current state of knowledge. Given rising rates of GDM, now estimated to be 14% globally, and widespread FA food fortification, further research is urgently needed to elucidate the mechanisms which underpin GDM pathogenesis.

Folic acid supplementation during pregnancy modulates hepatic methyl metabolism and genes expression profile of neonatal lambs of different litter sizes

Maternal folic acid (FA) plays an important role in the fetus development, but it is unknown the response of hepatic metabolism in the offspring from different litter sizes to maternal FA supplementation. In the present study, this was done by feeding the ewes with 0, 16 and 32 mg/(kg·DM) FA supplemented diet during pregnancy and analysing the hepatic one-carbon metabolism-related indices and gene expression in the neonatal lambs of different litter sizes (twins, TW; triplets, TR). Regardless of litter sizes, the concentrations of folate, methionine, S-adenosylmethionine and DNA methyltransferase increased significantly, but homocysteine and S-adenosylhomocysteine decreased in the liver of newborn lambs from ewes whose diet was supplemented with FA. In TW, maternal FA status has little effect on hepatic genes expression profile of newborn lambs, and no significant enriched pathway was found. However, DEG involved in cell proliferation such as CCNA2, CCNB2, CCNE2, CDK1 and BUB1 were significantly enriched when the ewes were supplemented with FA in TR groups. In addition, nucleotide synthesis-related genes such as POLD1, POLD2, MCM4 and MCM5 were enriched markedly in DNA replication and pyrimidine metabolism pathways in triplets when a higher FA ingestion [32 mg/(kg·DM)] was implemented in ewes. This finding demonstrated that the hepatic methyl metabolism in TW and TR newborn lambs was regulated by maternal FA status. The hepatic cell proliferation and nucleotide metabolism related genes in TR were more susceptible to maternal dietary FA supplementation during pregnancy.

Trimethylamine N-Oxide and Its Precursors Are Associated with Gestational Diabetes Mellitus and Pre-Eclampsia in the Boston Birth Cohort

Background

Trimethylamine N-oxide (TMAO) and its precursors choline, betaine, and carnitine have been associated with cardiometabolic disease in nonpregnant adults. However, studies examining TMAO and its precursors in relation to cardiometabolic conditions during pregnancy are lacking.

Objectives

The primary objective was to estimate the association of TMAO and its precursors in maternal and cord plasma with gestational diabetes mellitus (GDM) and pre-eclampsia (PE) among women in the Boston Birth Cohort. A secondary objective was to determine whether associations vary by race/ethnicity.

Methods

ORs for each outcome according to tertiles and to an SD increment of TMAO, choline, betaine, and carnitine were estimated using logistic regression. Final models were adjusted for covariates.

Results

Among 1496 women, 115 women had GDM and 159 had PE during the index pregnancy. Intermetabolite correlations of TMAO and its precursors were stronger within cord plasma (r = 0.38-0.87) than within maternal plasma (r = 0.08-0.62). Maternal TMAO was associated with higher odds of GDM (third compared with first tertile OR: 1.75; 95% CI: 1.04, 2.94), whereas maternal choline, betaine, and carnitine were not associated with GDM. Maternal TMAO and choline were not associated with PE, whereas carnitine was associated with higher (OR: 1.86; 95% CI: 1.18, 2.94) and betaine with lower odds of PE (OR: 0.37; 95% CI: 0.23, 0.59). In cord plasma, TMAO was not associated with GDM or PE, but choline, betaine, and carnitine were associated with higher odds of PE (OR: 3.11; 95% CI: 1.62, 5.96; OR: 2.65; 95% CI: 1.42, 4.93; OR: 2.56; 95% CI: 1.39, 4.69, respectively). Cord choline was associated with lower odds of GDM (OR: 0.52; 95% CI: 0.27, 0.99), whereas other cord metabolites were not significantly associated with GDM. Associations did not vary by race/ethnicity.

Conclusions

TMAO and its precursors were associated with GDM and PE, but the associations differed based on the metabolite medium (maternal compared with cord plasma).This trial was registered at clinicaltrials.gov as NCT03228875.

Continuous supplementation of folic acid in pregnancy and the risk of perinatal depression-A meta-analysis

BACKGROUND

The blood folic acid¹(FA) level of depressed patients seems to be lower than that of normal, and pregnant women are at greater risk of FA deficiency. The relationship between FA and perinatal depression has not been well described.

METHODS

We conducted a meta-analysis of the evidence for the association between the two, using current FA supplementation behavior during pregnancy and blood FA levels as exposures, and the incidence of perinatal depressive symptoms and mean Edinburgh Postnatal Depression Scale² (EPDS) scores as outcomes. The present study was recorded in PROSPERO (2019 CRD: 42,020,211,509).

RESULTS

Fifteen studies were identified, covering a total of 26,275 women from eleven observational studies and four randomized controlled trials. For the primary outcome of folic acid supplementation behavior and risk of perinatal depression, the overall odds ratio was 0.742 (95% CI: (0.647-0.852)), with a combined effect value of 0.84 (95% CI: (0.76, 0.93)) for studies in which an OR could be extracted. A negative association was observed between blood folate levels and depressive symptoms (Standardized mean difference (SMD) =-0.127, 95% CI:(-0.183,-0.071)). No association was observed between folic acid intervention and EPDS score. Continuous supplementation of folic acid during pregnancy may reduce the incidence of perinatal depressive symptoms (R = 0.017, (95 CI%:(0.014, 0.021)).

LIMITATIONS

Lack of rigorous randomized controlled trials due to ethical issues, and the research is heterogeneous and does not consider the influence of genetic factors.

CONCLUSIONS

Continuous use of FA during pregnancy may reduce the incidence of perinatal depressive symptoms.

Maternal micronutrient status and its association with sociodemographic, maternal, and dietary factors in a cross-sectional study

AIM

Maternal serum micronutrient status can have a significant impact on short- and long-term outcomes for mother and offspring. The aim of this study was to examine the associations of maternal serum folate, ferritin, and vitamin B₁₂ status with maternal and dietary factors.

METHODS

This observational cross-sectional study was carried out with 165 healthy pregnant women at least 18 years of age with a singleton pregnancy. Maternal nutrient intake was determined by 24-hour dietary recall method and supplement records. Multivariable analyses using stepwise linear regression models were performed to associations of dietary intakes and maternal serum status.

RESULTS

There was a difference between the lowest and highest quartile of maternal serum folate, ferritin, and vitamin B₁₂ status and maternal characteristics and dietary, and total intakes of nutrients (p < 0.05). Multivariable stepwise linear regression analysis showed the predictors of serum folate status were dietary folate equivalent, dietary folate, total vitamin B₆ and iron intake. Primer predictors of serum ferritin and vitamin B₁₂ status were dietary protein intake (p < 0.05).

CONCLUSION

Our findings support existing recommendations that folic acid supplementation should be prescribed to achieve optimal serum folate status during pregnancy. However, dietary protein intake is important to provide optimal maternal serum vitamin B₁₂ and ferritin status.

Association of polymorphisms of FOLR1 gene and FOLR2 gene and maternal folic acid supplementation with risk of ventricular septal defect: a case-control study

OBJECTIVES

It was the first time to examine the role of maternal polymorphisms of FOLR1 gene and FOLR2 gene, as well as their interactions with maternal folic acid supplementation (FAS), in the risk of ventricular septal defect (VSD).

METHODS

A case-control study was conducted with 385 mothers of VSD infants and 652 controls. The exposures of interest were FAS and FOLR1 gene and FOLR2 gene polymorphisms. The logistic regression model was used for accessing the strength of association.

RESULTS

After controlling for the potential confounders, women who did not utilize folic acid had a substantially higher risk of VSD (aOR = 2.25; 95% CI: 1.48 to 3.43), compared to those who did. We also observed genetic polymorphisms of FOLR1 gene at rs2071010 (GA vs. GG: aOR = 0.63, 95%CI: 0.45 to 0.88) and rs11235462 (AA vs. TT: aOR = 0.53, 95%CI: 0.33 to 0.84), as well as FOLR2 gene at rs651646 (AA vs. TT: aOR = 0.46, 95%CI: 0.30 to 0.70), rs2298444 (CC vs. TT: aOR = 0.58, 95%CI: 0.36 to 0.91) and rs514933 (TC vs. TT: aOR = 0.57, 95%CI: 0.41 to 0.78) were associated with a lower risk of VSD. Furthermore, there was a statistically significant interaction between maternal FAS and genetic polymorphisms at rs514933 on the risk of VSD (FDR_P = 0.015).

CONCLUSIONS

The maternal genetic polymorphisms of the FOLR1 gene and FOLR2 gene, as well as FAS and their interactions, were shown to be significantly associated with the risk of VSD in offspring.

Prenatal Folate and Choline Levels and Brain and Cognitive Development in Children: A Critical Narrative Review

Women’s nutritional status during pregnancy can have long-term effects on children’s brains and cognitive development. Folate and choline are methyl-donor nutrients and are important for closure of the neural tube during fetal development. They have also been associated with brain and cognitive development in children. Animal studies have observed that prenatal folate and choline supplementation is associated with better cognitive outcomes in offspring and that these nutrients may have interactive effects on brain development. Although some human studies have reported associations between maternal folate and choline levels and child cognitive outcomes, results are not consistent, and no human studies have investigated the potential interactive effects of folate and choline. This lack of consistency could be due to differences in the methods used to assess folate and choline levels, the gestational trimester at which they were measured, and lack of consideration of potential confounding variables. This narrative review discusses and critically reviews current research examining the associations between maternal levels of folate and choline during pregnancy and brain and cognitive development in children. Directions for future research that will increase our understanding of the effects of these nutrients on children’s neurodevelopment are discussed.

Periconceptional Folic Acid Supplementation and Newborn Birth Weights

BACKGROUND

The relationship between maternal folic acid supplementation and the birth weights of offspring remains inconclusive.

AIM

To examine the associations between maternal supplementation with folic acid only (FAO) or multiple micronutrients containing folic acid (MMFA) and newborn birth weights, as well as the risk of small for gestational week age (SGA) and large for gestational week age (LGA) newborns.

METHODS

Data on 31,107 births from 2015 to 2018 were extracted from the population-based prenatal health care system in a district of Beijing. Generalized linear and logistic regression models were used to evaluate the association between maternal periconceptional folic acid supplementation and birth weights or with risk of small for gestational week age (SGA) and large for gestational week age (LGA).

RESULTS

Compared with newborns whose mothers did not use any folic acid supplements, the newborns with maternal periconceptional folic acid supplementation had similar median birth weight but had a lower risk of SGA [adjusted odds ratio (aOR) = 0.81 (95% CI: 0.68-0.97)], however newborns born to mothers who took multiple micronutrients with folic acid (MMFA) with high compliance had a 25.59 g (95% CI: 6.49-44.69) higher median birth weight. Periconceptional women took folic acid only (FAO) (aOR = 0.83; 95%CI: 0.67-1.01) or MMFA (aOR = 0.74; 95%CI: 0.60-0.91) with high compliance decreased the risk of SGA, but has no impact on the risk of LGA.

CONCLUSION

Periconceptional FAO supplementation has no impact on the median birth weight of offspring and the risk of LGA. Compared with FAO, MMFA supplementation may increase the average birth weight, and a high compliance of supplementation with FAO or MMFA may reduce the risk of SGA, with MMFA having ad stronger effect than FAO.

Review of Evidence for Environmental Causes of Uveal Coloboma

Uveal coloboma is a condition defined by missing ocular tissues and is a significant cause of childhood blindness. It occurs from a failure of the optic fissure to close during embryonic development,and may lead to missing parts of the iris, ciliary body, retina, choroid, and optic nerve. Because there is no treatment for coloboma, efforts have focused on prevention. While several genetic causes of coloboma have been identified, little definitive research exists regarding the environmental causes of this condition. We review the current literature on environmental factors associated with coloboma in an effort to guide future research and preventative counseling related to this condition.

Profound changes in cerebrospinal fluid proteome and metabolic profile are associated with congenital hydrocephalus

The aetiology of congenital hydrocephalus (cHC) has yet to be resolved. cHC manifests late in rodent gestation, and by 18-22 weeks in human fetuses, coinciding with the start of the major phase of cerebral cortex development. Previously we found that cerebrospinal fluid (CSF) accumulation is associated with compositional changes, folate metabolic impairment and consequential arrest in cortical development. Here, we report a proteomics study on hydrocephalic and normal rat CSF using LC-MSMS and a metabolic pathway analysis to determine the major changes in metabolic and signalling pathways. Non-targeted analysis revealed a proteome transformation across embryonic days 17-20, with the largest changes between day 19 and 20. This provides evidence for a physiological shift in CSF composition and identifies some of the molecular mechanisms unleashed during the onset of cHC. Top molecular regulators that may control the shift in the CSF metabolic signature are also predicted, with potential key biomarkers proposed for early detection of these changes that might be used to develop targeted early therapies for this condition. This study confirms previous findings of a folate metabolic imbalance as well as providing more in depth metabolic analysis and understanding of cHC CSF.

Hyperhomocysteinemia and low vitamin B12 are associated with the risk of early pregnancy loss: A clinical study and meta-analyses

One-carbon metabolism is crucial for the maintenance of healthy pregnancy and alterations in this pathway have been associated with various pregnancy-related complications. Therefore, the present study was conducted to test the hypothesis that the altered folic acid, vitamin B12 and homocysteine levels are associated with the risk of early pregnancy loss (EPL). Plasma folic acid, vitamin B12 and homocysteine levels were analyzed in 83 females with EPL and 70 healthy pregnant females in their first trimester. Further, meta-analyses of folic acid, vitamin B12 and homocysteine were also performed involving various eligible studies. Results from our case-control study and meta-analysis showed that folic acid deficiency is not associated with the risk of EPL. On the other hand, low vitamin B12 and hyperhomocysteinemia were individually found to be significant risk factors for EPL in the present study (P < .01, P < .05, respectively) and meta-analysis as well (P < .001, P < .05, respectively). Vitamin B12 deficiency in combination with hyperhomocysteinemia was a more serious risk factor for EPL (Odds Ratio = 4.98, P = 0.002). Therefore, we conclude that vitamin B12 deficiency and elevated homocysteine levels are independent risk factors for EPL, and of higher risk when combined. The assessment of vitamin B12 and homocysteine levels may serve as a good screening marker for EPL risk.

Maternal diet and offspring telomere length: a systematic review

CONTEXT

Many studies assert a negative influence of inappropriate maternal diet and nutritional status during pregnancy on offspring, not only in utero but throughout life, because of the role in the programing of noncommunicable diseases. Telomere length is a biomarker of aging, and shorter telomeres are associated with chronic disease later in life. Maternal nutrition and nutritional status may be an important determinant of offspring telomere length.

OBJECTIVE

A systematic review was conducted to determine the effect of maternal nutrition and nutritional status in pregnancy on offspring telomere length.

DATA SOURCES

This systematic review was conducted according to PRISMA guidelines. Database searches of PubMed, CINAHL, Scopus, Medline, and Web of Science were performed.

STUDY SELECTION

Included studies assessed the association between maternal nutrition (dietary intake and nutritional status) during pregnancy and offspring telomere length measured in cord blood, serum, plasma, and peripheral blood mononuclear cells.

DATA EXTRACTION

Three authors screened and determined the quality of the articles; disagreements were resolved by a fourth author. All authors compared the compiled data.

RESULTS

Seven studies were extracted and evaluated. Studies comprised a double-blind placebo-controlled trial (n = 1), prospective cohort studies (n = 5), and a cross-sectional study (n = 1). Higher circulating maternal folate and 25-hydroxyvitamin D3 concentrations, along with higher maternal dietary caffeine intakes, were associated with longer offspring telomere length, whereas higher dietary intake of carbohydrate, folate, n-3 polyunsaturated fatty acids, vitamin C, or sodium was not.

CONCLUSION

The limited but suggestive evidence highlights the need for further research to be conducted in this area, particularly longitudinal studies involving larger cohorts of pregnant women.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO registration no. CRD42019136506.

Maternal homocysteine and folate levels and risk of recurrent spontaneous abortion: A meta-analysis of observational studies

AIM

The aim of the study was to review and summarize the epidemiologic evidence on the associations of homocysteine (HCY) and folate with the risk of recurrent spontaneous abortion (RSA).

METHODS

This review was performed following Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) guidelines. PubMed, Google Scholar, Cochrane Libraries and Chinese databases were searched through May 2019 to identify studies that met prestated inclusion criteria. Either a fixed- or a random-effects model was used to calculate the combined standardized mean difference (SMD) and 95% confidence intervals (CI).

RESULTS

Twenty-three studies involving 2052 RSA cases and 1476 healthy controls were included. Overall, women with RSA compared with those without RSA were at a significantly higher level of HCY both in plasma (SMD = 1.34; 95% CI: 0.76-1.93) and in serum (SMD = 1.46; 95% CI: 1.02-1.91), but lower level of folate both in serum (SMD = -1.63; 95% CI: -2.51 to -0.75) and in red blood cells (SMD = -1.30; 95% CI: -1.76 to -0.85). However, a statistically significant association between plasma folate and risk of RSA was not been observed (SMD = -0.82; 95% CI: -1.73 to 0.09). These findings have to be viewed with caution for the significant heterogeneity (I2: from 88 to 98%).

CONCLUSION

High HCY levels in both plasma and serum as well as low folate levels in serum and red blood cells are significantly associated with risk of RSA, which indicates that measures to reduce HCY levels or folate supplementation may help to reduce the risk of RSA. However, prospective studies are needed to confirm our findings.

Maternal Folic Acid Supplementation Differently Affects the Small Intestinal Phenotype and Gene Expression of Newborn Lambs from Differing Litter Sizes

The purpose of this study was to investigate the effect of maternal dietary folic acid (FA) supplementation during gestation on small intestinal development of newborn lambs of different litter sizes, focusing on the intestinal morphology and development-, apoptosis- and digestion-related genes expression. One hundred and twenty Hu ewes (Ovis aries) were inseminated and randomly allotted to three groups. One group received a control diet [without FA supplementation, control (CON)] and the other two groups received control diets supplemented with different amount of FA [16 or 32 mg FA per kg dry matter (DM), i.e., F16 and F32] during pregnancy. After lambing, according to the dietary FA levels and litter size (twins, TW; triplets, TR), the neonatal lambs were divided into 6 (TW-CON, TW-F16, TW-F32, TR-CON, TR-F16, TR-F32) treatment groups. The results showed that the ratio of small intestinal weight to live body weight and the thickness of the intestinal muscle layer in the offspring was enhanced significantly with increasing maternal FA supplementation (p < 0.05). Meanwhile, the expression levels of insulin-like growth factor I (IGF-I), B-cell lymphoma-2 (BCL-2) and sodium/glucose co-transporter-1 (SGLT1) in the small intestines of the newborn lambs were increased, while the opposite was true for Bcl2-associated × (BAX) in response to FA supplementation (p < 0.05). Moreover, the small intestinal weights of twins were significantly higher than those of triplets (p < 0.01), and the expression levels of IGF-I (p < 0.05), sucrase-isomaltase (SI) (p < 0.05) and solute carrier family 2 member 5 (SLC2A5) (p < 0.01) were significantly lower than those in triplets. These findings suggest that maternal FA supplementation could improve the offspring's small intestinal phenotype and the expression of development-, apoptosis- and digestion-related genes, so it could promote the small intestinal development of newborn lambs. Furthermore, the small intestine phenotypic development of twins was generally better than that of triplets, while the expression levels of the above genes of twins were lower than those of triplets.

Impact of extracellular folic acid levels on oviductal gene expression

Folate plays a specific role as methyl donor for nucleotide synthesis and genomic methylation patterns, which in turn are important epigenetic determinants in gene expression. Previous studies have revealed the presence of folate in bovine oviductal fluid as well as the existence of a fine-tuned regulation of the gene expression of folate receptors and transporters in bovine oviduct epithelial cells (BOECs). However, the functional implications of folate in the oviduct remain unknown. The present study aimed to assess the effect of folic acid (FA) on expression levels of selected genes that potentially respond to the folate status in in vitro BOECs. To obtain an insight into the optimization of a culture system for assays, gene expression of folate receptors and transporters was compared between BOECs grown in monolayers and in suspension. The results showed that BOECs from isthmus and ampulla in suspension culture better preserved the region-dependent gene expression profile than in monolayers. Subsequently, BOECs from both anatomical regions were separately cultured in suspension for 24 h assaying different FA concentrations: I) TCM-199 (control); II) TCM-199 + 1 μM FA (similar to the oviduct concentration); III) TCM-199 + 10 μM FA and IV) TCM-199 + 100 μM FA. Expression analysis of genes related to important cellular processes including folate transport, DNA methylation, cell-cell interaction, antioxidant activity and signaling pathways was performed in BOECs using RT-qPCR. Our data demonstrated that addition of 1 μM FA did not affect mRNA levels of most genes analyzed. In contrast, BOECs cultured with 10 μM FA exhibited increased mRNA expression levels of genes involved in folate intake, DNA methylation and antioxidant protection. It is worth noting that at 100 μM FA, transcriptional response in BOECs mainly resulted in decreased mRNA levels of the majority of the genes assayed. Interestingly, cytotoxicity analysis showed a similar LDH activity in the culture media of the experimental groups, indicating that cell integrity was not affected by the FA concentrations assayed. In conclusion, our findings suggest that folate can affect BOECs, promoting changes in gene activity in a framework of functional readjustments in response to environmental conditions.

Newborn micronutrient status biomarkers in a cluster-randomized trial of antenatal multiple micronutrient compared with iron folic acid supplementation in rural Bangladesh

BACKGROUND

Daily antenatal multiple micronutrient (MM) compared with iron folic acid (IFA) supplementation from early pregnancy improved birth outcomes and maternal micronutrient status in rural Bangladesh, but effects on newborn status are unknown.

OBJECTIVE

We examined cord blood micronutrient biomarkers in relation to antenatal MM and IFA supplementation and maternal gestational micronutrient status in rural Bangladeshi newborns.

DESIGN

In a double-blinded, cluster-randomized trial of antenatal IFA or MM (with the same IFA content), we analyzed cord blood plasma from 333 singleton births, and corresponding maternal plasma at 32.5 ± 2.6 wk of gestation, for ferritin (iron stores), folate, cobalamin (vitamin B-12), retinol (vitamin A), 25-hydroxyvitamin D [25(OH)D, vitamin D status], α-tocopherol (vitamin E), zinc, thyroglobulin, and free thyroxine (iodine status). Intervention effects and associations were determined using linear regression, exploring maternal status as a mediator of intervention effects on cord biomarkers.

RESULTS

The MM intervention increased cord ferritin (mean: +12.4%; 95% CI: 1.3, 24.6%), 25(OH)D (mean: +14.7%; 95% CI: 4.8, 25.6%), and zinc (mean: +5.8%; 95% CI: 1.0, 10.8%). Cord folate (mean: +26.8%; 95% CI: 19.6, 34.5%), cobalamin (mean: +31.3%; 95% CI: 24.6, 38.3%), 25(OH)D (mean: +26.7%; 95% CI: 23.2, 30.3%), α-tocopherol (mean: +8.7%; 95% CI: 3.6, 13.7%), zinc (mean: +2.3%; 95% CI: 0.5, 4.2%), thyroglobulin (mean: +20.1%; 95% CI: 9.0, 32.2%) and thyroxine (mean: +1.5%; 95% CI: 0.0, 3.0%) increased per 1-SD increment in maternal status (all P < 0.05); ferritin and retinol changed by +2.0%; 95% CI: -8.9, 14.3%; P = 0.72; and +3.5%; 95% CI: -0.4, 7.3%; P = 0.07, respectively. Ferritin, folate, cobalamin, zinc, and thyroglobulin averaged 1.57-6.75 times higher and retinol, α-tocopherol, and 25(OH)D 0.30-0.84 times lower in cord than maternal plasma, suggesting preferential maternal-fetal transfer of iron, folate, cobalamin, and zinc; limited transfer of fat-soluble vitamins; and high fetal iodine demand.

CONCLUSIONS

Antenatal MM supplementation increased newborn ferritin, 25(OH)D, and zinc, while maternal and newborn folate, vitamins B-12, D, and E, zinc, and iodine biomarkers were positively related. Despite limited effects of MM, better maternal micronutrient status was associated with improved micronutrient status of Bangladeshi newborns. This trial was registered at clinicaltrials.gov as NCT00860470.

Genetic Basis of Blood-Based Traits and Their Relationship With Performance and Environment in Beef Cattle at Weaning

The objectives of this study were to explore the usefulness of blood-based traits as indicators of health and performance in beef cattle at weaning and identify the genetic basis underlying the different blood parameters obtained from complete blood counts (CBCs). Disease costs represent one of the main factors determining profitability in animal production. Previous research has observed associations between blood cell counts and an animal’s health status in some species. CBC were recorded from approximately 570 Angus based, crossbred beef calves at weaning born between 2015 and 2016 and raised on toxic or novel tall fescue. The calves (N = ∼600) were genotyped at a density of 50k SNPs and the genotypes (N = 1160) were imputed to a density of 270k SNPs. Genetic parameters were estimated for 15 blood and 4 production. Finally, with the objective of identifying the genetic basis underlying the different blood-based traits, genome-wide association studies (GWAS) were performed for all traits. Heritability estimates ranged from 0.11 to 0.60, and generally weak phenotypic correlations and strong genetic correlations were observed among blood-based traits only. Genome-wide association study identified ninety-one 1-Mb windows that accounted for 0.5% or more of the estimated genetic variance for at least 1 trait with 21 windows overlapping across two or more traits (explaining more than 0.5% of estimated genetic variance for two or more traits). Five candidate genes have been identified in the most interesting overlapping regions related to blood-based traits. Overall, this study represents one of the first efforts represented in scientific literature to identify the genetic basis of blood cell traits in beef cattle. The results presented in this study allow us to conclude that: (1) blood-based traits have weak phenotypic correlations but strong genetic correlations among themselves. (2) Blood-based traits have moderate to high heritability. (3) There is evidence of an important overlap of genetic control among similar blood-based traits which will allow for their use in improvement programs in beef cattle.

Overview of Folic Acid Supplementation Alone or in Combination with Vitamin B12 in Dairy Cattle during Periparturient Period

The periparturient period is the period from three weeks before calving to three weeks post-calving. This period is important in terms of health, productivity and profitability, and is fundamental to successful lactation. During this period, the animal experiences stress because of hormonal changes due to pregnancy and the significant rise in milk production. In addition, a negative energy balance usually occurs, because the demand for nutrients to sustain milk production increases by more than the nutrient supply during the periparturient period. The immunity of dairy cattle is suppressed around parturition, which increases their susceptibility to infections. Special care regarding nutrition can reduce the risks of metabolism and immunity depression, which dairy cattle face during the periparturient span. Folic acid is relevant in this regard because of its critical role in the metabolism to maintain lactational performance and to improve health. Being a donor of one-carbon units, folic acid has a vital role in DNA and RNA biosynthesis. Generally, the folic acid requirements of dairy cattle can be met by the microbial synthesis in the rumen; however, in special cases, such as during the periparturient period, the requirement for this vitamin strictly increases. Vitamin B12 also has a critical role in the metabolism as a coenzyme of the enzyme methionine synthase for the transfer of a methyl group from folic acid to homocysteine for the regeneration of methionine. In the current review, we highlight the issues facing periparturient dairy cattle, and relevant knowledge and practices, and point out future research directions for utilization of the associated vitamins in ruminants, especially during the periparturient period.

Genetic and epigenetic MTHFR gene variants in the mothers of attention-deficit/hyperactivity disorder affected children as possible risk factors for neurodevelopmental disorders

Aim: To assess promoter methylation levels, gene expression levels and 677C>T/1298A>C genotype and allele frequencies of the MTHFR gene in 45 mothers of attention-deficit/hyperactivity disorder affected child/children (ADHDM) and compare it with age matched healthy control mothers (HCM). Materials & methods: High resolution melting analysis, quantitative real time PCR and PCR-RFLP were performed to assess methylation, gene expression and genotyping, respectively. Significance between ADHDM and HCM was assessed by linear (methylation and gene expression) and logistic regression (genotypes). Results: MTHFR gene expression levels were significantly higher in the ADHDM compared with the HCM group (adj-p < 7.7E-04). No differences in MTHFR promoter methylation level and 677C>T/1298A>C genotype frequencies were detected between ADHDM and HCM. Conclusion: We observed increased MTHFR expression levels not resulting from promoter methylation changes in ADHDM respect to HMC, potentially contributing to the ADHD condition in their children and deserving further investigation.

Distribution of 5-Methyltetrahydrofolate and Folic Acid Levels in Maternal and Cord Blood Serum: Longitudinal Evaluation of Japanese Pregnant Women

“Total” folate in blood has usually been measured to evaluate the folate status of pregnant women. However, folate is composed of many metabolites. The main substrate is 5-methyltetrahydrofolate (5-MTHF), with folic acid (FA) representing a very small component as an unmetabolized species in blood. We longitudinally evaluated 5-MTHF, FA and total homocysteine in maternal and cord blood from Japanese pregnant women. Subjects were 146 pregnant women who participated in the Chiba study of Mother and Child Health (C-MACH) prospective cohort study. Sera were obtained in early and late pregnancy, at delivery, and from cord blood. Species levels were measured by isotope-dilution mass spectrometry. Both 5-MTHF and FA levels were lower than reported levels from pregnant women in populations from countries with mandatory FA fortification. As gestational age progressed, serum 5-MTHF levels decreased, whereas serum FA levels were slightly reduced only at delivery compared to early pregnancy. A significant negative association between serum 5-MTHF and total homocysteine was shown at all examined times, but no associations with FA were evident. At delivery, cord 5-MTHF was significantly higher than maternal levels, while FA again showed no significant correlation. These results suggest that 5-MTHF is actively transported to the fetus through placental transporters and may reflect folate status during pregnancy as a physiologically important species.

Maternal Cotinine Levels and Red Blood Cell Folate Concentrations in the Periconceptual Period

OBJECTIVES

Studies have examined the association between tobacco use and folate levels in pregnancy, yet few have assessed this relation using objective and accurate measures of both smoking and folate. In this study, we evaluated the association between maternal cotinine levels and periconceptional red blood cell (RBC) folic acid reserves in a cohort of low-income pregnant mothers.

METHODS

Smoking information, based on salivary cotinine, a highly sensitive and specific tobacco smoke exposure biomarker, was used. Furthermore, folate was assessed using RBC folate, an indicator of long-term folate storage. Participants were early to mid-trimester pregnant women who received antenatal care between 2011 and 2015 at the Genesis Clinic of Tampa (Florida). A total of 496 women were enrolled in the study. Associations between smoking status/maternal salivary cotinine concentrations, sociodemographic factors, and folate concentrations were investigated using Tobit regression analyses.

RESULTS

The mean folate level of the participants was 718.3 ± 183.2 ng/mL, and only 2 (0.4%) participants were deficient in folate. We observed no significant difference in folate levels by smoking status. In contrast, salivary cotinine levels were significantly associated with decreased RBC folate concentrations (β -11.43, standard error 5.45, P = 0.032). Prepregnancy maternal body mass index, gestational age, stress, and depression also were associated with folate levels.

CONCLUSIONS

Low RBC folate is associated with perinatal factors, including high maternal cotinine levels, body mass index, stress, and depression. The effect of low folate levels among smokers cannot be overemphasized, considering that tobacco products not only reduce folate levels but also decrease the bioutilization of folate.

Folic Acid and Risk of Preterm Birth: A Meta-Analysis

The results from epidemiologic studies linking blood folate concentrations, folic acid supplementation, or dietary folate to the risk of preterm birth are inconsistent. In this study, we aimed to summarize the available evidence on these associations. A systematic search of the PubMed/MEDLINE, Google Scholar, Web of Science, and Cochrane Library databases up to October 20, 2018 was performed and reference lists of retrieved articles were screened. Pooled odds ratios (ORs) and 95% confidence intervals (CIs) for the highest vs. the lowest levels of folate concentrations, folic acid supplementation, and dietary folate were calculated using random-effects models. Subgroup analyses and univariate meta-regression were performed to explore the sources of heterogeneity. Ten studies (six prospective cohort studies and four case-control studies) were included on folate concentrations, 13 cohort studies were included about folic acid supplementation, and 4 cohort studies were included regarding dietary folate intake. Higher maternal folate levels were associated with a 28% reduction in the risk of preterm birth (OR 0.72, 95% CI 0.56–0.93). Higher folic acid supplementation was associated with 10% lower risk of preterm birth (OR 0.90, 95% CI 0.85–0.95). In addition, a significant negative association was observed between dietary folate intake and the risk of preterm birth (OR 0.68, 95% CI 0.55–0.84), but no significant relation was seen between dietary folate and the risk of spontaneous preterm birth (OR 0.89, 95% CI 0.57–1.41). In the subgroup analysis, higher maternal folate levels in the third trimester were associated with a lower risk of preterm birth (OR 0.58, 95% CI 0.36–0.94). To initiate taking folic acid supplementation early before conception was adversely associated with preterm birth risk (OR 0.89, 95% CI 0.83–0.95). In conclusion, higher maternal folate levels and folic acid supplementation were significantly associated with a lower risk of preterm birth. The limited data currently available suggest that dietary folate is associated with a significantly decreased risk of preterm birth.

Decreased placental folate transporter expression and activity in first and second trimester in obese mothers

Obese women have an approximately twofold higher risk to deliver an infant with neural tube defects (NTDs) despite folate supplementation. Placental transfer of folate is mediated by folate receptor alpha (FR-α), proton coupled folate transporter (PCFT), and reduced folate carrier (RFC). Decreased placental transport may contribute to NTDs in obese women. Serum folate levels were measured and placental tissue was collected from 13 women with normal BMI (21.9±1.9) and 11 obese women (BMI 33.1±2.8) undergoing elective termination at 8-22 weeks of gestation. The syncytiotrophoblast microvillous plasma membranes (MVM) were isolated using homogenization, magnesium precipitation, and differential centrifugation. MVM expression of FR-α, PCFT and RFC was determined by western blot. Folate transport capacity was assessed using radiolabeled methyl-tetrahydrofolate and rapid filtration techniques. Differences in expression and transport capacity were adjusted for gestational age and maternal age in multivariable regression models. P<.05 was considered statistically significant. Serum folate levels were not significantly different between groups. Placental MVM folate transporter expression did not change with gestational age. MVM RFC (-19%) and FR-α (-17%) expression was significantly reduced in placentas from obese women (P<.05). MVM folate transporter activity was reduced by-52% (P<.05) in obese women. These differences remained after adjustment for gestational age. There was no difference in mTOR signaling between groups. In conclusion, RFC and FR alpha expression and transporter activity in the placental MVM are significantly reduced in obese women in early pregnancy. These results may explain the higher incidence of NTDs in infants of obese women with adequate serum folate.

Altered folate binding protein expression and folate delivery are associated with congenital hydrocephalus in the hydrocephalic Texas rat

Hydrocephalus (HC) is an imbalance in cerebrospinal fluid (CSF) secretion/absorption resulting in fluid accumulation within the brain with consequential pathophysiology. Our research has identified a unique cerebral folate system in which depletion of CSF 10-formyl-tetrahydrofolate-dehydrogenase (FDH) is associated with cortical progenitor cell-cycle arrest in hydrocephalic Texas (H-Tx) rats. We used tissue culture, immunohistochemistry, in-situ PCR and RT-PCR and found that the in-vitro proliferation of arachnoid cells is highly folate-dependent with exacerbated proliferation occurring in hydrocephalic CSF that has low FDH but high folate-receptor-alpha (FRα) and folate. Adding FDH to this CSF prevented aberrant proliferation indicating a regulatory function of FDH on CSF folate concentration. Arachnoid cells have no detectable mRNA for FRα or FDH, but FDH mRNA is found in the choroid plexus (CP) and CSF microvesicles. Co-localization of FDH, FRα and folate suggests important functions of FDH in cerebral folate transport, buffering and function. In conclusion, abnormal CSF levels of FDH, FRα and folate inhibit cortical cell proliferation but allow uncontrolled arachnoid cell division that should increase fluid absorption by increasing the arachnoid although this fails in the hydrocephalic brain. FDH appears to buffer available folate to control arachnoid proliferation and function.

Evaluation of folate concentration in amniotic fluid and maternal and umbilical cord blood during labor

INTRODUCTION

Folate is required for fetal, placental and maternal tissue growth during pregnancy. A decline in maternal circulating folate concentrations and an increase in total homocysteine (a non-specific indicator of folate deficiency) have been observed with the progression of pregnancy. However, the role of folate in the third trimester of pregnancy is not clear and folate status in late pregnancy has not so far been widely analyzed. The main aim of this retrospective cross-sectional study was to determine the folate concentrations in amniotic fluid and in maternal and umbilical cord blood serum derived during delivery.

MATERIAL AND METHODS

This study was conducted on 175 pregnant Polish women (white/Caucasian) aged between 17 and 42 years. Only pregnancies without birth defects were included in this study. Amniotic fluid, maternal serum, and umbilical cord blood samples were collected during vaginal delivery or cesarean section. Folate concentration was determined using a microbiological assay.

RESULTS

Strong correlations were observed between the concentrations of folate in amniotic fluid and maternal serum (rho = 0.67, p < 0.001) and amniotic fluid and cord blood serum (rho = 0.49, p < 0.001) and between maternal serum and cord blood serum (rho = 0.67, p < 0.001). Folate concentrations in amniotic fluid were significantly associated with maternal age (rho = 0.19, p < 0.05). Pre-pregnancy body mass index and maternal weight/neonatal birth weight ratio were independent predictors of folate concentrations in maternal serum (β = 0.33, p < 0.05; β = -0.19, p < 0.05) and amniotic fluid (β = 0.28, p < 0.05; β = -0.19, p < 0.05) in late pregnancy.

CONCLUSIONS

Folate concentrations in amniotic fluid are associated with maternal and neonatal folate status peripartum in healthy women.

Folic acid, but not folate, regulates different stages of neurogenesis in the ventral hippocampus of adult female rats

Folate is an important regulator of hippocampal neurogenesis, and folic acid is needed prenatally to reduce the risk of neural tube defects. Both high levels of folic acid and low levels of folate can be harmful to health because low levels of folate have been linked to several diseases while high folic acid supplements can mask a vitamin B₁₂ deficiency. Depressed patients exhibit folate deficiencies, lower levels of hippocampal neurogenesis, elevated levels of homocysteine and elevated levels of the stress hormone, cortisol, which may be inter-related. In the present study, we were interested in whether different doses of natural folate or synthetic folic acid diets can influence neurogenesis in the hippocampus, levels of plasma homocysteine and serum corticosterone in adult female rats. Adult female Sprague-Dawley rats underwent dietary interventions for 29 days. Animals were randomly assigned to six different dietary groups: folate deficient + succinylsulphathiazole (SST), low 5-methyltetrahydrofolate (5-MTHF), low 5-MTHF + (SST), high 5-MTHF + SST, low folic acid and high folic acid. SST was added to a subset of the 5-MTHF diets to eliminate folic acid production in the gut. Before and after dietary treatment, blood samples were collected for corticosterone and homocysteine analysis, and brain tissue was collected for neurogenesis analysis. High folic acid and low 5-MTHF without SST increased the number of immature neurones (doublecortin-expressing cells) within the ventral hippocampus compared to folate deficient controls. Low 5-MTHF without SST significantly increased the number of immature neurones compared to low and high 5-MTHF + SST, indicating that SST interfered with elevations in neurogenesis. Low folic acid and high 5-MTHF + SST reduced plasma homocysteine levels compared to controls, although there was no significant effect of diet on serum corticosterone levels. In addition, low folic acid and high 5-MTHF + SST reduced the number of mature new neurones in the ventral hippocampus (bromodeoxyuridine/NeuN-positive cells) compared to folate deficient controls. Overall, folic acid dose-dependently influenced neurogenesis with low levels decreasing but high levels increasing neurogenesis in the ventral hippocampus, suggesting that this region, which is important for regulating stress, is particularly sensitive to folic acid in diets. Furthermore, the addition of SST negated the effects of 5-MTHF to increase neurogenesis in the ventral hippocampus.

Genetic polymorphisms of the cobalamin transport system are associated with idiopathic recurrent implantation failure

PURPOSE

Vitamin B12 (cobalamin, Cbl) plays a role in the recycling of folate, which is important in pregnancy. Transcobalamin II (TCN2) and transcobalamin receptor (TCblR) proteins are involved in the cellular uptake of Cbl. TCN2 binds Cbl in the plasma, and TCblR binds TCN2-Cbl at the cell surface. Therefore, we investigated the potential association between polymorphisms in Cbl transport proteins, TCN2 and TCblR, and recurrent implantation failure (RIF) susceptibility.

METHODS

The genotypes of TCN2 67A>G, TCN2 776C>G, and TCblR 1104C>T were determined for RIF patients and healthy controls using a polymerase chain reaction restriction fragment length polymorphism assay. Additionally, statistical analysis was performed to compare the genotype frequencies between RIF patients and controls.

RESULTS

The TCN2 67 polymorphism AG type was associated with RIF risk. Some allele combinations that contained the TCN2 67 polymorphism G allele were associated with increased RIF risk, whereas other allele combinations that contained the TCblR 1104 polymorphism T alleles were associated with decreased RIF risk. In genotype combination analysis, two combinations containing the TCN2 67 polymorphism AG type were associated with RIF risk.

CONCLUSION

Our study showed that the polymorphisms of TCN2 and TCblR are associated with RIF and are potential genetic predisposing factors for RIF among Korean women. Additionally, our findings support a potential role for TCN2 and TCblR in RIF among Korean women. However, further studies are required to investigate the role of the polymorphisms in those proteins and RIF because the roles of the TCN2 and TCblR polymorphisms in RIF are not clear.

Review and meta-analysis found that prenatal folic acid was associated with a 58% reduction in autism but had no effect on mental and motor development

AIM

The impact of prenatal folic acid on children's neurodevelopment and the risk of autism spectrum disorder (ASD) remain unclear and this review and meta-analysis aimed to quantify any associations.

METHODS

We systematically searched PubMed, Scopus and The Cochrane Library until June 2018 with no language restrictions. Standardised mean differences and odds ratio with 95% confidence intervals are used to describe any associations between folic acid and mental development, motor development and ASD.

RESULTS

The search strategy identified 647 papers and 16 were finally included in the meta-analysis after the application of the exclusion criteria. These provided a total cohort size of 756 365 children aged 11 months to 15 years from 10 countries. The main finding was that prenatal use of folic acid was associated with a 58% reduction in the risk of ASD in children. We were surprised that better scores for mental development were associated with low prenatal exposure to folic acid.

CONCLUSION

Although the results should be interpreted with caution, they showed that routine prenatal supplements of folic acid were associated with significantly lower levels of ASD. Further studies are needed to reach a firm conclusion, given the multifactorial aetiology of neurodevelopment.

Altered methyltetrahydrofolate reductase gene polymorphism in mothers of children with attention deficit and hyperactivity disorder

Attention Deficit and Hyperactivity Disorder (ADHD) is one of the most common psychiatric disorders in childhood and causes significant functional impairments in children. Behavioral genetic and molecular genetic studies have provided significant evidence in terms of highlighting the etiology of ADHD. Folate deficiency during pregnancy is an established risk factor for ADHD. Polymorphisms in the Methyltetrahydrofolate Reductase (MTHFR) encoding gene, such as A1298C and C667T, are associated with the decreased bioavailability of folate, and this condition can act like folate deficiency. In the literature, no study has investigated MTHFR polymorphisms in mothers of children with ADHD. Sixty-four children diagnosed with ADHD and their mothers as well as 40 healthy children and their mothers participated in this study. MTHFR polymorphisms were investigated in all participants. Comparison of the C677C and A1298C MTHFR polymorphisms in children with and without ADHD revealed no significant differences. We found that the maternal C677C_CT genotype counts, both observed and expected values, were significantly different from those based on Hardy-Weinberg Principle Analysis in the ADHD group. The most important result of this study was that maternal C677C MTHFR gene polymorphisms are significant risk factors in for ADHD, and we argue that children with ADHD are exposed to folate deficiency, even if their mothers received a sufficient amount of folate during pregnancy. This result also highlights one of the genetic factors of ADHD. Further studies should be performed to confirm this finding.

The Impact of Maternal Pre-Pregnancy Body Weight and Gestational Diabetes on Markers of Folate Metabolism in the Placenta

Dietary methyl donors, including folate, may modify the placenta and size at birth but the influence of maternal body weight has not been widely investigated. We therefore examined whether maternal or fetal folate status, together with indices of placental folate transport, were modulated by either maternal pre-pregnancy body mass index (BMI i.e., overweight: 25 ≤ BMI < 30 or obesity: BMI ≥ 30 kg/m²) and/or gestational diabetes mellitus (GD). We utilised a sub-sample of 135 pregnant women participating in the Spanish PREOBE survey for our analysis (i.e., 59 healthy normal weight, 29 overweight, 22 obese and 25 GD). They were blood sampled at 34 weeks gestation, and, at delivery, when a placental sample was taken together with maternal and cord blood. Placental gene expression of folate transporters and DNA methyltransferases (DNMT) were all measured. Folate plasma concentrations were determined with an electro-chemiluminescence immunoassay. Food diaries indicated that folate intake was unaffected by BMI or GD and, although all women maintained normal folate concentrations (i.e., 5–16 ng/mL), higher BMIs were associated with reduced maternal folate concentrations at delivery. Umbilical cord folate was not different, reflecting an increased concentration gradient between the mother and her fetus. Placental mRNA abundance for the folate receptor alpha (FOLR1) was reduced with obesity, whilst DNMT1 was increased with raised BMI, responses that were unaffected by GD. Multi-regression analysis to determine the best predictors for placental FOLR1 indicated that pre-gestational BMI had the greatest influence. In conclusion, the placenta’s capacity to maintain fetal folate supply was not compromised by either obesity or GD.

Farletuzumab, a monoclonal antibody directed against folate receptor alpha, shows no evidence of teratogenicity in cynomolgus monkeys

Farletuzumab is a humanized monoclonal antibody targeting human folate receptor alpha, which is being developed as an anti-cancer drug. A non-human primate reproductive study was conducted to evaluate whether it could cause any embryonic or fetal abnormalities. Farletuzumab was administered intravenously to pregnant cynomolgus monkeys (n = 16/group) at doses of 0 or 67.5 mg/kg once weekly during gestation day (GD) 20 through 97. C-section was performed on GD100 ± 2, and fetuses were evaluated for morphologic (external, visceral and skeletal) effects. No farletuzumab-related changes were observed in maternal animals or fetuses, which are supported by the fact that farletuzumab has no effects on cellular uptake of folate. These data support the potential use of farletuzumab for oncologic indications during pregnancy.

Exposure to different intrauterine environments: implications for telomere attrition in early life

Objective: Studies focusing on telomere attrition in newborns and what factors could be involved in this issue are sparse; most reports have been in adult populations. Thereby, the aim of this study was to present an overview of what is currently known about the relationship between environmental exposure of the fetus during pregnancy and telomere length outcomes in early life. Methods: The MEDLINE (via PubMed) and Bireme databases were searched for studies published until 1 June 2016. Studies that reported telomere length measurement from birth to age 1 year were included. Results: Fifteen articles were selected that evaluated possible relationships between maternal smoking, hyperglycemia, hypertension, sleep apnea, psychological stress, folate concentration in early pregnancy, and radiation, in addition to small-for-gestational-age status and preterm birth. We found that sleep apnea, psychological stress, and folate concentration in early pregnancy were associated with telomere shortening in the newborn. No association was found with radiation, small-for-gestational-age status, or preterm birth. Results for maternal smoking, hyperglycemia, and hypertension were conflicting, and further studies should be considered. Conclusion: The actual clinical implications of these findings have yet to be investigated.

The effects of high and low doses of folic acid on oxidation of protein levels during pregnancy: a randomized double-blind clinical trial

Objective

Oxidants include important active molecules which are created in the body and attack biological molecules especially lipids, carbohydrates, nucleic acids and proteins, and cause oxidation and various diseases in the body. Antioxidants existing in the body help to avoid the incidence of these injuries. Pregnant women are among those where oxidation of biological molecules may do irreparable damage to them and their embryos. So, the purpose of this study was to review the effect of folic acid with both high (5 mg/day) and low (0.5 mg/day) doses on the changes of oxidative protein in reducing plasma homocystein concentration during pregnancy.

Materials and methods

Forty-five pregnant women participated in this study. They were divided into two groups: group 1 included 23 women who received 5 mg/day folic acid and group 2 included 23 women who took 0.5 mg/day folic acid before pregnancy till the 36th week pregnancy. We measured the biochemical variables in the serum of pregnant women at the beginning and at the end of the study.

Results

Folic acid reduced plasma homocytein in both low and high dose groups (p = 0.035, p = 0.012, respectively). Also, the results showed that folic acid prescription led to reduce plasma level of carbonyl groups in both low and high dose groups (p = 0.01, p = 0.03, respectively). Furthermore, the results showed that there is no significant difference between two groups and folic acid affects both groups equally.

Conclusion

It is possible that folic acid administration can reduce plasma homocysteine and carbonyl levels during pregnancy in dose independent manner

No evidence for association of MTHFR 677C>T and 1298A>C variants with placental DNA methylation

Background

5,10-Methylenetetrahydrofolate reductase (MTHFR) is a key enzyme in one-carbon metabolism that ensures the availability of methyl groups for methylation reactions. Two single-nucleotide polymorphisms (SNPs) in the MTHFR gene, 677C>T and 1298A>C, result in a thermolabile enzyme with reduced function. These variants, in both the maternal and/or fetal genes, have been associated with pregnancy complications including miscarriage, neural tube defects (NTDs), and preeclampsia (PE), perhaps due to altered capacity for DNA methylation (DNAm). In this study, we assessed the association between MTHFR 677TT and 1298CC genotypes and risk of NTDs, PE, or normotensive intrauterine growth restriction (nIUGR). Additionally, we assessed whether these high-risk genotypes are associated with altered DNAm in the placenta.

Results

In 303 placentas screened for this study, we observed no significant association between the occurrence of NTDs (N = 55), PE (early-onset: N = 28, late-onset: N = 20), or nIUGR (N = 21) and placental (fetal) MTHFR 677TT or 1298CC genotypes compared to healthy pregnancies (N = 179), though a trend of increased 677TT genotype in PE/IUGR together was observed (OR 2.53, p = 0.048). DNAm was profiled in 10 high-risk 677 (677TT + 1298AA), 10 high-risk 1298 (677CC + 1298CC), and 10 reference (677CC + 1298AA) genotype placentas. Linear modeling identified no significantly differentially methylated sites between high-risk 677 or 1298 and reference placentas at a false discovery rate < 0.05 and Δβ ≥ 0.05 using the Illumina Infinium HumanMethylation450 BeadChip. Using a differentially methylated region analysis or separating cytosine-guanine dinucleotides (CpGs) by CpG density to reduce multiple comparisons also did not identify differential methylation. Additionally, there was no consistent evidence for altered methylation of repetitive DNA between high-risk and reference placentas.

Conclusions

We conclude that large-scale, genome-wide disruption in DNAm does not occur in placentas with the high-risk MTHFR 677TT or 1298CC genotypes. Furthermore, there was no evidence for an association of the 1298CC genotype and only a tendency to higher 677TT in pregnancy complications of PE/IUGR. This may be due to small sample sizes or folate repletion in our Canadian population attenuating effects of the high-risk MTHFR variants. However, given our results and the conflicting results in the literature, investigations into alternative mechanisms that may explain the link between MTHFR variants and pregnancy complications, or in populations at risk of folate deficiencies, are warranted.

Electronic supplementary material

The online version of this article (10.1186/s13148-018-0468-1) contains supplementary material, which is available to authorized users.

Folate Deficiency and Anemia Among Women of Reproductive Age (15-49 Years) in Senegal: Results of a National Cross-Sectional Survey

Background:

Widely spread throughout the world, folate and iron deficiencies are risk factors for many diseases. However, contrary to iron deficiency and anemia, which have been documented in depth, the prevalence of folate deficiency among women has not been well-studied.

Objective:

The aim of this study is to determine the prevalence of folate deficiency and anemia and their association among Senegalese women of reproductive age.

Methods:

A national cross-sectional survey using a stratified 2-stage cluster sampling was conducted. Data were collected from 1012 women (aged 15-49 years). Plasma folate and hemoglobin (Hb), as well as protein markers of subclinical infections, were equally measured.

Results:

The mean folate concentration was 8.50 nmol/L (8.16-8.85 nmol/L), and 54.8% of the women were folate deficient (<10 nmol/L). Plasma folate concentration of rural women (7.27 nmol/L [6.89-7.68 nmol/L]) and urban women (10.45 nmol/L [9.88-11.05 nmol/L]) was significantly different ( P < .0001), the highest concentration being observed in women living in Dakar, the capital of Senegal. The breastfeeding women showed lower plasma folate concentration compared to nonbreastfeeding ones: 6.97 nmol/L (6.37-7.63 nmol/L) versus 9.03 nmol/L (8.61-9.46 nmol/L). Overall, 27% of the women were suffering from inflammation/infections. Mean Hb concentration was 116.86 (1.18) g/L, and 47.63% of the women involved in the study were anemic (pregnant women Hb <110 g/L; nonpregnant Hb <120 g/L). Also, a positive and significant correlation was found between plasma folate and Hb concentrations ( r = .07; P = .0167).

Conclusions:

This study showed a high prevalence of folate deficiency and anemia among Senegalese women (15-49 years), particularly those living in rural settings and breastfeeding women.

Immunometabolism, pregnancy, and nutrition

The emerging field of immunometabolism has substantially progressed over the last years and provided pivotal insights into distinct metabolic regulators and reprogramming pathways of immune cell populations in various immunological settings. However, insights into immunometabolic reprogramming in the context of reproduction are still enigmatic. During pregnancy, the maternal immune system needs to actively adapt to the presence of the fetal antigens, i.e., by functional modifications of distinct innate immune cell subsets, the generation of regulatory T cells, and the suppression of an anti-fetal effector T cell response. Considering that metabolic pathways have been shown to affect the functional role of such immune cells in a number of settings, we here review the potential role of immunometabolism with regard to the molecular and cellular mechanisms necessary for successful reproduction. Since immunometabolism holds the potential for a therapeutic approach to alter the course of immune diseases, we further highlight how a targeted metabolic reprogramming of immune cells may be triggered by maternal anthropometric or nutritional aspects.

Mutations in folate transporter genes and risk for human myelomeningocele

The molecular mechanisms linking folate deficiency and neural tube defect (NTD) risk in offspring remain unclear. Folate transporters (SLC19A1, SLC46A1, SLC25A32, and FOLH1) and folate receptors (FOLR1, FOLR2, and FOLR3) are suggested to play essential roles in transporting folate from maternal intestinal lumen to the developing embryo. Loss of function variants in these genes may affect folate availability and contribute to NTD risk. This study examines whether variants within the folate transporter and receptor genes are associated with an increased risk for myelomeningocele (MM). Exons and their flanking intron sequences of 348 MM subjects were sequenced using the Sanger sequencing method and/or next generation sequencing to identify variants. Frequencies of alleles of single nucleotide polymorphisms (SNPs) in MM subjects were compared to those from ethnically matched reference populations to evaluate alleles' associated risk for MM. We identified eight novel variants in SLC19A1 and twelve novel variants in FOLR1, FOLR2, and FOLR3. Pathogenic variants include c.1265delG in SLC19A1 resulting in an early stop codon, four large insertion deletion variants in FOLR3, and a stop_gain variant in FOLR3. No new variants were identified in SLC46A1, SLC25A32, or FOLH1. In SLC19A1, c.80A>G (rs1051266) was not associated with our MM cohort; we did observe a variant allele G frequency of 61.7%, higher than previously reported in other NTD populations. In conclusion, we discovered novel loss of function variants in genes involved in folate transport in MM subjects. Our results support the growing evidence of associations between genes involved in folate transport and susceptibility to NTDs.

Mechanistic Target of Rapamycin Is a Novel Molecular Mechanism Linking Folate Availability and Cell Function

Folate deficiency has been linked to a wide range of disorders, including cancer, neural tube defects, and fetal growth restriction. Folate regulates cellular function mediated by its involvement in the synthesis of nucleotides, which are needed for DNA synthesis, and its function as a methyl donor, which is critical for DNA methylation. Here we review current data showing that folate sensing by mechanistic target of rapamycin (mTOR) constitutes a novel and distinct pathway by which folate modulates cell functions such as nutrient transport, protein synthesis, and mitochondrial respiration. The mTOR signaling pathway responds to growth factors and changes in nutrient availability to control cell growth, proliferation, and metabolism. mTOR exists in 2 complexes, mTOR complex (mTORC) 1 and mTORC2, which have distinct upstream regulators and downstream targets. Folate deficiency in pregnant mice caused a marked inhibition of mTORC1 and mTORC2 signaling in multiple maternal and fetal tissues, downregulation of placental amino acid transporters, and fetal growth restriction. In addition, folate deficiency in primary human trophoblast (PHT) cells resulted in inhibition of mTORC1 and mTORC2 signaling and decreased the activity of key amino acid transporters. Folate sensing by mTOR in PHT cells is independent of the accumulation of homocysteine and requires the proton-coupled folate transporter (PCFT; solute carrier 46A1). Furthermore, mTORC1 and mTORC2 regulate trophoblast folate uptake by modulating the cell surface expression of folate receptor α and the reduced folate carrier. These findings, which provide a novel link between folate availability and cell function, growth, and proliferation, may have broad biological significance given the critical role of folate in normal cell function and the multiple diseases that have been associated with decreased or excessive folate availability. Low maternal folate concentrations are linked to restricted fetal growth, and we propose that the underlying mechanisms involve trophoblast mTOR folate sensing resulting in inhibition of mTORC1 and mTORC2 and downregulation of placental amino acid transporters.