Is there a reduction of congenital abnormalities in the offspring of diabetic pregnant women after folic acid supplementation? A population-based case-control study

Nutrient Transporter Gene Expression in the Early Conceptus-Implications From Two Mouse Models of Diabetic Pregnancy

Maternal diabetes in early pregnancy increases the risk for birth defects in the offspring, particularly heart, and neural tube defects. While elevated glucose levels are characteristic for diabetic pregnancies, these are also accompanied by hyperlipidemia, indicating altered nutrient availability. We therefore investigated whether changes in the expression of nutrient transporters at the conception site or in the early post-implantation embryo could account for increased birth defect incidence at later developmental stages. Focusing on glucose and fatty acid transporters, we measured their expression by RT-PCR in the spontaneously diabetic non-obese mouse strain NOD, and in pregnant FVB/N mouse strain dams with Streptozotocin-induced diabetes. Sites of expression in the deciduum, extra-embryonic, and embryonic tissues were determined by RNAscope in situ hybridization. While maternal diabetes had no apparent effects on levels or cellular profiles of expression, we detected striking cell-type specificity of particular nutrient transporters. For examples, Slc2a2/Glut2 expression was restricted to the endodermal cells of the visceral yolk sac, while Slc2a1/Glut1 expression was limited to the mesodermal compartment; Slc27a4/Fatp4 and Slc27a3/Fatp3 also exhibited reciprocally exclusive expression in the endodermal and mesodermal compartments of the yolk sac, respectively. These findings not only highlight the significance of nutrient transporters in the intrauterine environment, but also raise important implications for the etiology of birth defects in diabetic pregnancies, and for strategies aimed at reducing birth defects risk by nutrient supplementation.

Systematic review and meta-analysis of the effectiveness of pre-pregnancy care for women with diabetes for improving maternal and perinatal outcomes

Background

Pre-gestational diabetes mellitus is associated with increased risk of maternal and perinatal adverse outcomes. This systematic review was conducted to evaluate the effectiveness and safety of pre-conception care (PCC) in improving maternal and perinatal outcomes.

Methods

Databases from MEDLINE, EMBASE, WEB OF SCIENCE, and Cochrane Library were searched, including the CENTRAL register of controlled trials, and CINHAL up until March 2019, without any language restrictions, for any pre-pregnancy care aiming at health promotion, glycemic control, and screening and treatment of diabetes complications in women with type I or type II pre-gestational diabetes. Trials and observational studies were included in the review. Newcastle-Ottawa scale and the Cochrane collaboration methodology for data synthesis and analysis were used, along with the GRADE tool to evaluate the body of evidence.

Results

The search identified 8500 potentially relevant citations of which 40 reports of 36 studies were included. The meta-analysis results show that PCC reduced congenital malformations risk by 71%, (Risk ratio (RR) 0.29; 95% CI: 0.21–0.40, 25 studies; 5903 women; high-certainty evidence). The results also show that PCC may lower HbA1c in the first trimester of pregnancy by an average of 1.27% (Mean difference (MD) 1.27; 95% CI: 1.33–1.22; 4927 women; 24 studies, moderate-certainty evidence). Furthermore, the results suggest that PCC may lead to a slight reduction in the risk of preterm delivery of 15%, (RR 0.85; 95% CI: 0.73–0.99; nine studies, 2414 women; moderate-certainty evidence). Moreover, PCC may result in risk reduction of perinatal mortality by 54%, (RR 0.46; 95% CI: 0.30–0.73; ten studies; 3071 women; moderate-certainty evidence). There is uncertainty about the effects of PCC on the early booking for antenatal care (MD 1.31; 95% CI: 1.40–1.23; five studies, 1081 women; very low-certainty evidence) and maternal hypoglycemia in the first trimester, (RR 1.38; 95% CI: 1.07–1.79; three studies; 686 women; very low- certainty evidence). In addition, results of the meta-analysis indicate that PCC may lead to 48% reduction in the risk of small for gestational age (SGA) (RR 0.52; 95% CI: 0.37–0.75; six studies, 2261 women; moderate-certainty evidence). PCC may reduce the risk of neonatal admission to intensive care unit (NICU) by 25% (RR 0.75; 95% CI: 0.67–0.84; four studies; 1322 women; moderate-certainty evidence). However, PCC may have little or no effect in reducing the cesarean section rate (RR 1.02; 95% CI: 0.96–1.07; 14 studies; 3641 women; low-certainty evidence); miscarriage rate (RR 0.86; 95% CI: 0.70–1.06; 11 studies; 2698 women; low-certainty evidence); macrosomia rate (RR 1.06; 95% CI: 0.97–1.15; nine studies; 2787 women, low-certainty evidence); neonatal hypoglycemia (RR 0.93; 95% CI: 0.74–1.18; five studies; 880 women; low-certainty evidence); respiratory distress syndrome (RR 0.78; 95% CI: 0.47–1.29; four studies; 466 women; very low-certainty evidence); or shoulder dystocia (RR 0.28; 95% CI: 0.07–1.12; 2 studies; 530 women; very low-certainty evidence).

Conclusion

PCC for women with pre-gestational type 1 or type 2 diabetes mellitus is effective in improving rates of congenital malformations. In addition, it may improve the risk of preterm delivery and admission to NICU. PCC probably reduces maternal HbA1C in the first trimester of pregnancy, perinatal mortality and SGA. There is uncertainty regarding the effects of PCC on early booking for antenatal care or maternal hypoglycemia during the first trimester of pregnancy. PCC has little or no effect on other maternal and perinatal outcomes.

Association of MTHFR C677T, MTHFR A1298C, and MTRR A66G Polymorphisms with Neural Tube Defects in Tunisian Parents

OBJECTIVE

This study aims to investigate the association of 5,10-methylenetetrahydrofolate reductase (MTHFR C677T and A1298C) and methionine synthase reductase (MTRR A66G) gene polymorphisms with neural tube defects (NTDs) in a Tunisian population.

METHODS

Genotyping was performed by polymerase chain reaction with restriction fragment length polymorphisms (PCR-RFLPs) using the restriction enzymes. Allele and genotype frequencies were compared between mothers and fathers of fetuses with NTDs with matched controls based on an association analysis using SPSS software.

RESULTS

MTHFR (C677T, A1298C) and MTRR A66G polymorphisms were found to be protector factors for NTD fetuses in the mother group. In addition, a combination of the three wild-type alleles C677/A1298/A66 has increased four-fold the incidence of NTDs (p = 0.004, OR = 3.96, 95% CI: 1.53-10.23). In the father group, MTHFR C677T was a risk factor for NTDs. However, no association was found between MTHFR A1298C, MTRR A66G, and the occurrence of this anomaly. The analysis of MTHFR C677T and MTRR A66G polymorphisms has demonstrated a significant difference in vitamin B12 levels between recessive and dominant genotypes in case mothers (p < 0.05).

CONCLUSION

Additional studies are required to better understand the roles of parental gene polymorphisms related to folate-homocysteine metabolism in the pathogenesis of NTD.

Acid folic and pregnancy: A mandatory supplementation

Neural tube defects (NTD) occur in 0.5 to 2 per 1000 pregnancies with various handicaps for the affected child. It is now well established that folic acid deficiency (absolute or relative) is a predisposing factor to this type of malformation. Several randomized controlled trials showed that high-dose folic acid (4mg) is an essential factor for prevention of neural tube defects recurrence and significantly prevents the first occurrence of neural tube defects with a lower dose (0.4mg). Other etiologies can favor the occurrence of NTD such as MTHFR polymorphism, some antiepileptic therapies, obesity and pregestational mellitus diabetes. Necessity of a preconception folic acid supplementation or at least folate nutritional status evaluation should be known for all of us including patients and public.

Reevaluation of Antioxidative Strategies for Birth Defect Prevention in Diabetic Pregnancies

Diabetes mellitus in early pregnancy is the most severe maternal disease that is counted for 10% of newborn infants with structural defects. With the rapid increases in the number of diabetic women in childbearing age, the birth defect rate is projected to elevate dramatically. Thus, prevention of embryonic malformations becomes an urgent task. Animal studies have revealed an involvement of oxidative stress in diabetic embryopathy and treatment with antioxidants can reduce embryonic abnormalities. However, the failure of clinical trials using free radical-scavenging antioxidants to alleviate oxidative stress-related diseases prompts researchers to reevaluate the strategy in birth defect prevention. Hyperglycemia also disturbs other intracellular homeostasis, generating aberrant conditions. Perturbed folding of newly synthesized proteins causes accumulation of unfolded and misfolded proteins in the lumen of the endoplasmic reticulum (ER). The ER under the stress activates signaling cascades, known as unfolded protein response, to suppress cell mitosis and/or trigger apoptosis. ER stress can be ameliorated by chemical chaperones, which promote protein folding. Hyperglycemia also stimulates the expression of nitric oxide (NO) synthase 2 (NOS2) to produce high levels of NO and reactive nitrogen species and augment protein nitrosylation and nitration, resulting in nitrosative stress. Inhibition of NOS2 using inhibitors has been demonstrated to reduce embryonic malformations in diabetic animals. Therefore, targeting ER and nitrosative stress conditions using specific agents to prevent birth defects in diabetic pregnancies warrant further investigations. Simultaneously targeting multiple stress conditions using combined agents is a potentially effective and feasible approach.

Folic acid supplementation in pregnancy and implications in health and disease

Maternal exposure to dietary factors during pregnancy can influence embryonic development and may modulate the phenotype of offspring through epigenetic programming. Folate is critical for nucleotide synthesis, and preconceptional intake of dietary folic acid (FA) is credited with reduced incidences of neural tube defects in infants. While fortification of grains with FA resulted in a positive public-health outcome, concern has been raised for the need for further investigation of unintended consequences and potential health hazards arising from excessive FA intakes, especially following reports that FA may exert epigenetic effects. The objective of this article is to discuss the role of FA in human health and to review the benefits, concerns and epigenetic effects of maternal FA on the basis of recent findings that are important to design future studies.

C677T mutation in methylenetetrahydrofolate reductase gene and neural tube defects: should Japanese women undergo gene screening before pregnancy?

We analyzed the role of maternal C677T mutation in methylenetetrahydrofolate reductase (MTHFR) gene on spina bifida development in newborns. A total of 115 mothers who had given birth to a spina bifida child (SB mothers) gave 10 mL of blood together with written informed consent. The genotype distribution of C677T mutation was assessed and compared with that of the 4517 control individuals. The prevalence of the homozygous genotype (TT) among SB mothers was not significantly different from that among the controls (odds ratio [OR] = 0.65; 95% confidence interval [CI] = 0.31-1.25; P = 0.182), suggesting that MTHFR 677TT genotype in Japan is not associated with spina bifida development in newborns. The T allele frequency was not increased in SB mothers (34.8%) as compared to that of the control individuals (38.2%). Further, the internationally reported association between the two groups was found to be similar in all 15 countries studied except the Netherlands, where the TT genotype was found to be a genetic risk factor for spina bifida. For the prevention of affected pregnancy every woman planning to conceive has to take folic acid supplements 400 μg a day and the government is asked to take action in implementing food fortification with folic acid in the near future. In conclusion, it is not necessary for Japanese women to undergo genetic screening C677T mutation of the MTHFR gene as a predictive marker for spina bifida prior to pregnancy, because the TT genotype is not a risk factor for having an affected infant.

Risk factors in the origin of congenital left-ventricular outflow-tract obstruction defects of the heart: a population-based case-control study

The aim of our project was to study possible etiological factors in the origin of congenital heart defects (CHDs) because in the majority of patients the underlying causes are unclear. Cases with different CHD entities as homogeneously as possible were planned for evaluation in the population-based large data set of the Hungarian Case Control Surveillance of Congenital Abnormalities. Dead or surgically corrected 302 live-born cases with different types of left-ventricular outflow tract obstructive defects (LVOT, i.e., valvular aortic stenosis 76, hypoplastic left heart syndrome 76, coarctation of the aorta 113, and other congenital anomalies of aorta 32) were compared with 469 matched controls, 38,151 controls without any defects, and 20,750 malformed controls with other isolated defects. Medically recorded pregnancy complications and chronic diseases were evaluated based on prenatal maternity logbooks, whereas acute diseases, drug treatments, and folic acid/multivitamin supplementation were analyzed both on the basis of retrospective maternal information and medical records. The results of the study showed the role of maternal diabetes in the origin of LVOT in general, while panic disorder was associated with a higher risk of hypoplastic left heart syndrome and ampicillin treatment with a higher risk of coarctation of the aorta (COA). High doses of folic acid had a protective effect regarding the manifestation of LVOT, particularly COA. In conclusion, only a minor portion of causes was shown in our study; thus, further studies are needed to understand better the underlying causal factors in the origin of LVOT.

Position of folic acid in fortification of nutrition in neonatal period

Folic acid is an essential vitamin which has been known in recent 50 years. It plays an important role in period of neurogenesis. The substitution of folic acid is one of the important parts in the complex treatment of anaemia in premature newborns. It is also a component of artificial milk formulae or breast milk following mother’s intake. Fortification of foods with folic acid for population in the world is still discussed. To determine optimal dose of folic acid in premature newborns is difficult. Daily recommended doses of folic acid in infants under the six months were identified. The needs of folic acid in newborns vary. It depends upon the gestational age, body reserves at birth or maternal status of folates during gravidity. On the other hand there is a risk of accumulation of unmetabolised folic acid in circulation of newborns after mandatory folic acid fortification in some countries, which were reported in some studies. The safe upper limits of folic acid intake in premature newborns are not known. In this review article authors inform about the clear positive effect of folic acid in prenatal and neonatal period, but excessive doses of folic acid could present risk of accumulation and possible adverse effects. To follow up these notions further studies are required.

Modeling anterior development in mice: diet as modulator of risk for neural tube defects

Head morphogenesis is a complex process that is controlled by multiple signaling centers. The most common defects of cranial development are craniofacial defects, such as cleft lip and cleft palate, and neural tube defects, such as anencephaly and encephalocoele in humans. More than 400 genes that contribute to proper neural tube closure have been identified in experimental animals, but only very few causative gene mutations have been identified in humans, supporting the notion that environmental influences are critical. The intrauterine environment is influenced by maternal nutrition, and hence, maternal diet can modulate the risk for cranial and neural tube defects. This article reviews recent progress toward a better understanding of nutrients during pregnancy, with particular focus on mouse models for defective neural tube closure. At least four major patterns of nutrient responses are apparent, suggesting that multiple pathways are involved in the response, and likely in the underlying pathogenesis of the defects. Folic acid has been the most widely studied nutrient, and the diverse responses of the mouse models to folic acid supplementation indicate that folic acid is not universally beneficial, but that the effect is dependent on genetic configuration. If this is the case for other nutrients as well, efforts to prevent neural tube defects with nutritional supplementation may need to become more specifically targeted than previously appreciated. Mouse models are indispensable for a better understanding of nutrient-gene interactions in normal pregnancies, as well as in those affected by metabolic diseases, such as diabetes and obesity.

Risk and protective factors in the origin of conotruncal defects of heart--a population-based case-control study

Congenital heart defect (CHD) cases have been evaluated together as a group in some previous epidemiological studies. However, different CHD entities have different etiologies, and the underlying causes are unclear in the vast majority of patients. Thus the aim of this study was to analyze the possible association of different maternal diseases with the risk of four types of conotruncal defects (CTD), that is, truncus arteriosus, d-transposition of the great arteries, tetralogy of Fallot, and double-outlet right ventricle based on autopsy or surgical report diagnosis. Acute and chronic diseases with related drug treatments and peri-conceptual folic acid or multivitamin supplementations were compared in mothers of 598 CTD cases, of 902 matched controls, and 38,151 population controls without any defects, and with 20,896 malformed controls with other isolated non-cardiac defects in the population-based large dataset of the Hungarian Case-Control Surveillance of Congenital Abnormalities. Mothers who had medically recorded influenza and the common cold with secondary complications in the prenatal maternity logbook during the second and/or third gestational months were associated with a higher risk of CTD (OR with 95% CI: 2.22, 1.19-3.88). The common denominator of these maternal diseases may be high fever, which could be prevented by antifever therapies. On the other hand, high doses of medically recorded folic acid in early pregnancy were able to reduce the birth prevalence of CTD (OR with 95% CI: 0.54, 0.39-0.73), and this reduction was significant in transposition of the great arteries (0.46, 0.29-0.71) as well. In conclusion, high fever related maternal diseases may have a role in the origin of CTD, while high doses of folic acid in early pregnancy were able to reduce of CTD, particularly transposition of great vessels.

Safety and fortification with folic acid in neonatal period

Folic acid, the essential vitamin, and its active forms are substantial parts of many biochemical processes in the human body. In the period of rapid growth of organism or in cell growth, body’s demands for folate increase. Its impact in neonatal period varies even in premature newborns. Fortification with folic acid and its substitution in the treatment of anaemia are the important parts in the comprehensive care in premature newborns. To determine optimal dose in this group of patients is difficult. The determination of red blood cell folate concentration levels is the most accurate indicator of long-term folate level status in the body. Unmetabolised folic acid in circulation of newborns could have potentially adverse effects. Toxicity of folic acid is not a concern as folate is water-soluble and easily excreted by kidneys when in excess but on the other side growing organism of preterm newborn and disruption of metabolic balance could be potential risks.

Folic acid supplementation changes the fate of neural progenitors in mouse embryos of hyperglycemic and diabetic pregnancy

Folic acid has been shown to decrease the incidence of neural tube defects (NTDs) in normal and hyperglycemic conditions, but the influence of folic acid on the development of central nervous system is not fully understood. Here, we aimed to explore the effects of folic acid, especially high dose of folic acid, on the characteristics of neural progenitors in embryos of hyperglycemic and diabetic mouse. Hyperglycemic and diabetic pregnant mice were given 3 mg/kg or 15 mg/kg folic acid from embryonic day 0.5 (E0.5) and were euthanased on E11.5, E13.5 or E18.5. The incidence of NTDs at E13.5 was counted. The proliferation, apoptosis and differentiation of neural progenitors and neuronal migration were determined using BrdU incorporation assay, TUNEL assay, immunofluorescence, Western blot and real-time reverse transcriptase polymerase chain reaction. Both normal and high doses of folic acid decreased the incidence of NTDs, promoted proliferation and reduced apoptosis of neuroepithelial cells in embryos of hyperglycemic and diabetic mice. Importantly, folic acid, especially at high dose, might affect the premature differentiation of neural progenitors in embryos of hyperglycemic and diabetic pregnancy. This may be attributed to changes of messenger RNA expression levels of some basic-helix-loop-helix transcription factors. In addition, folic acid might be involved in regulating neuronal migration in embryos of hyperglycemic and diabetic pregnancy. These findings suggest that periconceptional supplementation of folic acid, especially at high dose, may be a double-edged sword because it may result in undesirable outcomes affecting both the neuronal and glial differentiation in hyperglycemic and diabetic pregnancy.

Folic acid supplementation in pregnancy: are there devils in the detail?

Maternal folic acid (FA) supplementation is well recognised to protect against neural tube defects. Folate is a critical cofactor in one-carbon metabolism involved in the epigenetic regulation of transcription that underpins development. Thus, it is possible that maternal FA supplementation may have additional, unforeseen persistent effects in the offspring. This is supported by the modification by maternal supplementation with one-carbon donors and FA of the epigenetic regulation of offspring phenotype in mutant mice. The present article reviews studies in human subjects and experimental animals of the effect of maternal FA intake and phenotypic outcomes in the offspring. Maternal FA intake was associated with a short-term increased incidence of allergy-related respiratory impairment in children and multigenerational respiratory impairment in rats. Higher maternal folate status during pregnancy was associated positively with insulin resistance in 6-year-olds. In rats, maternal FA supplementation modified hepatic metabolism and vascular function through altered transcription, in some cases underpinned by epigenetic changes. FA supplementation in pregnant rats increased mammary tumorigenesis, but decreased colorectal cancer in the offspring. Maternal FA supplementation decreased a range of congenital cardiac defects in children. These findings support the view that maternal FA supplementation induces persistent changes in a number of phenotypic outcomes in the offspring. However, the number of studies is limited and insufficient to indicate a need to change current recommendations for FA intake in pregnancy. Nevertheless, such effects should be investigated thoroughly in order to support firm conclusions about the risk of unanticipated long-term negative effects of maternal FA supplementation in humans.

Diabetes-induced birth defects: what do we know? What can we do?

Birth defects are the leading cause of infant mortality in the United States, which has one of the highest infant mortality rates in the developed world. Many of these birth defects can be attributed to pre-existing, or pregestational, diabetes in pregnancy, which significantly increases a mother's risk of having a child with a major birth defect. Strict preconceptional and early pregnancy glucose control, supplementation with multivitamins and fatty acids, and lower glycemic dietary management have been shown to reduce the incidence of birth defects in experimental and epidemiologic studies. However, because more than half of pregnancies are unplanned, these methods are not generalizable across the population. Thus, better interventions are urgently needed. Based on what we know about the molecular pathophysiology of diabetic embryopathy, our laboratory and others are developing interventions against to key molecular targets in this multifactorial disease process.

Primary prevention of neural-tube defects and some other congenital abnormalities by folic acid and multivitamins: history, missed opportunity and tasks

The history of intervention trials of periconception folic acid with multivitamin and folic acid supplementation in women has shown a recent breakthrough in the primary prevention of structural birth defects, namely neural-tube defects and some other congenital abnormalities. Recently, some studies have demonstrated the efficacy of this new method in reducing congenital abnormalities with specific origin; for example, in the offspring of diabetic and epileptic mothers, and in pregnancy with high fever. The benefits and drawbacks of four possible uses of periconception folate/folic acid and multivitamin supplementation are discussed: we believe there has been a missed opportunity to implement this preventive approach in medical practice. The four methods are as follows: (i) dietary intake of folate and other vitamins, (ii) periconception folic acid/multivitamin supplementation, (iii) food fortification with folic acid, and (iv) the combination of oral contraceptives with 6S-5-methytetrahydrofolate ('folate').