Comparison of serum folate, 25-OH vitamin D, and calcium levels between pregnants with and without fetal anomaly of neural tube origin

Vitamin D Supplementation and Vitamin D Status during Pregnancy and the Risk of Congenital Anomalies-A Systematic Review and Meta-Analysis

Maternal dietary factors have been suggested as possible contributing influences for congenital anomalies (CAs). We aimed to assess the association between vitamin D supplementation or vitamin D status (s-25OHD) during pregnancy and CAs in the offspring. A comprehensive literature search was conducted in the three electronic databases: PubMed, Embase, and Cochrane Library. Included studies were critically appraised using appropriate tools (risk of bias 2, ROBINS-I). A protocol was registered in the International Prospective Register of Systematic Reviews (CRD42019127131). A meta-analysis of four randomised controlled trials (RCTs) including 3931 participants showed no effect of vitamin D supplementation on CAs, a relative risk of 0.76 (95% CI 0.45; 1.30), with moderate certainty in the effect estimates by GRADE assessment. Of the nine identified observational studies, six were excluded due to a critical risk of bias in accordance with ROBINS-I. Among the included observational studies, two studies found no association, whereas one case-control study identified an association between s-25OHD < 20 nmol/L and neural tube defects, with an adjusted odds ratio of 2.34 (95% CI: 1.07; 5.07). Interpretation of the results should be cautious given the low prevalence of CAs, RCTs with onset of supplementation after organogenesis, and low-quality observational studies.

Impact of prenatal exposure to metallic elements on neural tube defects: Insights from human investigations

Metallic elements play a pivotal role in maternal and fetal health. Metals can cross the placental barrier and be absorbed by fetuses, where they may affect closure of the neural tube during embryonic development. Neural tube defects (NTDs), which result from aberrant closure of the neural tube three to four weeks post-conception, have a multifactorial and complex etiology that combines genetic variants and environmental exposure. Recent advances in population-level association studies have investigated the link between maternal environmental exposure and NTDs, particularly the influence of metals on the incidence of NTDs. Herein, we present a broad and qualitative review of current literature on the association between maternal and prenatal metal exposure via the maternal peripheral blood, amniotic fluid, placenta, umbilical cord, and maternal hair, and the risk of developing NTDs. Specifically, we identify the various aggravating or attenuating effects of metallic exposure on the risk of NTD formation. This review provides novel insights into the association between environmental metals and NTDs and has important applications for NTD prevention and mitigating environmental exposure to metals.

Impact of Maternal and Neonatal Vitamin D Status on the Development of Congenital Anomalies in Egyptian Model

Background: Vitamin D (VD) is a remarkable problem during pregnancy. VD plays a crucial role in cellular growth and differentiation during embryogenesis. VD deficiency in pregnancy is associated with various maternal and neonatal comorbidities.  Aim: In this study, we aimed to evaluate the potential association between maternal and neonatal vitamin D status and the subsequent development of congenital anomalies. Patients and methods: A case-control study involving 30 mothers and their neonates born with gross structural congenital anomalies as cases and 30 mothers and their healthy neonates as controls recruited from Ain Shams University Children Hospital. Maternal and Neonatal blood samples were obtained to determine serum 25-hydroxyvitamin D.  The 25-hydroxyvitamin D concentration was stratified into a severe deficient<10ng/ml, deficient <20ng/ml, insufficient 20-29ng/ml and sufficient >30ng/ml. Status above 150ng/ml presents high risk of toxicity.  Results: There were statistically significant differences between the two groups regarding maternal and neonatal vitamin D serum level within 29 days postpartum. Mean maternal vitamin D level in cases was 23.8ng/ml versus 42.13ng/ml in controls (P = 0,000). Mean neonatal vitamin D level in cases was 15.97ng/ml versus 28.9ng/ml in controls (P = 0,000).There was significant positive correlation between both maternal and neonatal vitamin D level with birth weight. Conclusion: A compromised maternal vitamin D status is associated with an increased prevalence of congenital anomalies in offspring. Therefore, improvement of the periconceptional maternal vitamin D status is recommended.

The role of Vitamin B12 and genetic risk factors in the etiology of neural tube defects: A systematic review

Neural tube defects (NTDs) are birth defects that arise during embryogenesis when normal neural tube closure fails to occur. According to the World Health Organization, NTDs are detected annually in approximately 300,000 neonates worldwide. The exact etiology of NTDs remains complex and poorly understood. It is generally agreed that most NTD cases are of multifactorial origin, having a combination of multiple genes and a number of environmental risk factors. The role of folic acid, vitamin B12 deficiency, genetics and other risk factors, in the etiology of NTDs, has also been extensively studied. This knowledge synthesis brings together different types of evidence to update the role of vitamin B12 deficiency, genetics and other risk factors, in the etiology of NTDs. Following a PubMed search and screening for relevant articles, we included 40 studies in our review (30 case-control studies, 3 cross-sectional studies, 5 cohort studies, and 2 case reports). The available data showed that vitamin B12 levels were decreased in mothers and infants in NTD groups compared with control groups. Holo-transcobalamin, the active form of vitamin B12, was also found in lower levels in mothers with NTD-affected infants. Several studies reported elevated homocysteine levels in mothers and infants in NTD groups. Additionally, numerous studies reported links between genetic variants and increased NTD risk. These genes include GIF, LRP2, CUBN, TCb1R, MTHFR, and others. Several maternal factors have also been linked with significant NTD risk such as BMI, maternal diet, air pollutants, low maternal age, and many others. The majority of studies on NTDs have focused on the role of folic acid, hence there is a need for well-designed studies on the role of other risk factors like vitamin B12 deficiency in the etiology of NTDs.

Prenatal exposure to barium and the occurrence of neural tube defects in offspring

Neural tube defects (NTDs) have a complex etiology. Few studies have assessed alkaline earth metals exposures and occurrence of NTDs. We examined the association between prenatal exposure to magnesium (Mg), calcium (Ca), strontium (Sr) and barium (Ba) and risk for NTDs in a case-control study, and assessed the teratogenic effects of Ba on mice. Placentas were collected from 408 women with NTD-affected pregnancies and 593 women who delivered healthy infants, and concentrations of these metals were determined as prenatal exposure markers. The single effect of individual exposure and joint effect of coexposure to these metals were evaluated with logistic regression and Bayesian kernel machine regression (BKMR), respectively. Barium chloride (BaCl₂) was intragastrically administered to pregnant ICR mice and fetal mice were examined for NTDs. Median concentrations of Mg and Ba were higher in NTD cases than in controls (P_all < 0.001). In logistic regression, higher levels of Ba were associated with 1.6-fold increased risk for NTDs (95% confidence interval: 1.06-2.43). In BKMR, the joint effect of the four-metal mixture on NTD risk increased steadily with the levels of the mixture. A change in Ba concentration from the 25^th to 75^th percentile displayed a risk effect when the other three metals were fixed at the 25^th, 50^th or 75^th percentile, while such a change in Ca concentration showed a protective effect when the other metals were held at the 25^th or 50^th percentile. No interactions among metals were found. In the mouse experiment, dams treated with 200 mg/kg BaCl₂ showed 16.8% of NTDs in fetal mice, compared to 2.6% in the untreated control group (P < 0.01). Taken together, higher mixture levels of the four alkaline earth metals were associated with increased risk for NTDs, with Ba being the major contributor for the joint effect. Intragastric administration of Ba can induce NTDs in mice.