Maternal obesity, folate intake, and neural tube defects in offspring

Chromium levels in placental tissue and neural tube defects: Association and mechanistic study

Human exposure to chromium (Cr) is common but little is known about its adverse effects on pregnancy outcomes. This study aimed to explore the association between Cr exposure and the risk of neural tube defects (NTDs) and the underlying mechanisms of Cr-induced NTDs. 593 controls and 408 NTD cases with placentas were included in this study. Chromium trichloride (Cr(III)) and potassium dichromate (Cr(VI)) were intragastrically administered to pregnant mice and the number of NTDs was recorded. The odds ratio for total NTDs in the highest exposure group in placenta was 4.18 (95% confidence interval (CI), 1.97-8.84). The incidence of fetal NTDs in mice administered with Cr(III) showed a dose-response relationship. Cr(VI) didn't show teratogenicity of NTDs whereas increased the stillbirth rate. Prenatal exposure to Cr(III) increased levels of oxidative stress and apoptosis in fetal mice. RNA-sequencing results indicated significant enrichment of the MAPK pathway. RT-qPCR and Western blot analysis revealed that Cr(III) induced increased expression of p-JNK, p-P38, and Casp3. Toxicological effects can be partly antagonized by antioxidant supplementation. High chromium exposure was associated with increased human NTD risks. Excessive Cr(III) exposure can induce NTDs in fetal mice by increasing apoptosis through upgrading oxidative stress and then activating JNK/P38 MAPK signaling pathway.

The Importance of Neurosurgical Intervention and Surgical Timing for Management of Pediatric Patients with Myelomeningoceles in Bangladesh

OBJECTIVE

Reports on the management and survival of children with myelomeningocele defects in Bangladesh are limited. This study describes the characteristics and outcomes of these children, focusing on the timing of surgical repair and factors affecting survival.

METHODS

We enrolled patients with myelomeningoceles in a case-control study on arsenic exposure and spina bifida in Bangladesh. Cases were subsequently followed at regular intervals to assess survival. Demographic, clinical, and surgical characteristics were reviewed. Univariate tests identified factors affecting survival.

RESULTS

Between 2016 and 2022, we enrolled 272 patients with myelomeningocele. Postnatal surgical repair was performed in 63% of cases. However, surgery within 5 days after birth was infrequent (<10%) due to delayed presentation, and there was a high rate (29%) of preoperative deaths. Surgical repair significantly improved patient survival (P < 0.0001). Older age at time of surgery was also associated with improved survival rates, which most likely represents that those who survived to older ages prior to surgery accommodated better with their lesions. Patients who presented with ruptured lesions had lower survival rates.

CONCLUSIONS

Timely neurosurgical repair of myelomeningoceles in Bangladesh is hindered by late patient presentation, resulting in a high preoperative patient death rate. Neurosurgical intervention remains a significant predictor of survival. Increased access to neurosurgical care and education of families and non-neurosurgical providers on the need for timely surgical intervention are important for improving the survival of infants with myelomeningoceles.

Periconceptional biomarkers for maternal obesity: a systematic review

Periconceptional maternal obesity is linked to adverse maternal and neonatal outcomes. Identifying periconceptional biomarkers of pathways affected by maternal obesity can unravel pathophysiologic mechanisms and identify individuals at risk of adverse clinical outcomes. The literature was systematically reviewed to identify periconceptional biomarkers of the endocrine, inflammatory and one-carbon metabolic pathways influenced by maternal obesity. A search was conducted in Embase, Ovid Medline All, Web of Science Core Collection and Cochrane Central Register of Controlled Trials databases, complemented by manual search in PubMed until December 31^st, 2020. Eligible studies were those that measured biomarker(s) in relation to maternal obesity, overweight/obesity or body mass index (BMI) during the periconceptional period (14 weeks preconception until 14 weeks post conception). The ErasmusAGE score was used to assess the quality of included studies. Fifty-one articles were included that evaluated over 40 biomarkers. Endocrine biomarkers associated with maternal obesity included leptin, insulin, thyroid stimulating hormone, adiponectin, progesterone, free T4 and human chorionic gonadotropin. C-reactive protein was associated with obesity as part of the inflammatory pathway, while the associated one-carbon metabolism biomarkers were folate and vitamin B12. BMI was positively associated with leptin, C-reactive protein and insulin resistance, and negatively associated with Free T4, progesterone and human chorionic gonadotropin. Concerning the remaining studied biomarkers, strong conclusions could not be established due to limited or contradictory data. Future research should focus on determining the predictive value of the optimal set of biomarkers for their use in clinical settings. The most promising biomarkers include leptin, adiponectin, human chorionic gonadotropin, insulin, progesterone and CRP.

Folate, Vitamin B12, and Homocysteine Levels in Women With Neural Tube Defect-Affected Pregnancy in Addis Ababa, Ethiopia

Background

Neural tube defects (NTDs) are prevalent congenital defects associated with pre-pregnancy diet with low levels of maternal folate. They are linked to severe morbidity, disability, and mortality, as well as psychological and economic burdens.

Objective

The goal of this study was to determine the levels of folate, vitamin B12, and homocysteine in the blood of women who had a pregnancy impacted by NTDs.

Subjects and Methods

A hospital-based case–control study was undertaken between September 2019 and August 2020. The study comprised a total of 100 cases and 167 controls. Enzyme-linked immunosorbent assay (ELISA) was used to determine the levels of folate, vitamin B12, and homocysteine in the serum.

Results

Only 39% of the cases and 54.5% of control mothers reported periconceptional use of folic acid/multivitamin, which indicated a statistically significant difference (p = 0.014). Logistic regression indicated that periconceptional use of folic acid/multivitamin was associated with NTDs (p = 0.015, OR = 1.873, 95% CI: 1.131–3.101). We found that 57% of the cases and 33.5% of controls, as well as 43% of cases and 20.4% of controls had serum folate and vitamin B12 levels below the cut-off value, respectively. Twenty-seven percent of the cases and 6.6% of controls had hyperhomocysteinemia (HHcy). The median concentrations of folate, vitamin B12, and homocysteine in cases and controls were 4.78 and 8.86 ng/ml; 266.23 and 455 pg/ml; 13.43 and 9.7 μmol/l, respectively. The median concentration of folate (p < 0.001) and vitamin B12 (p < 0.001) were significantly lower in the cases than controls, while the homocysteine concentration (p < 0.001) was significantly lower in the controls than cases. Folate [OR (95% CI) = 1.652 (1.226–2.225; p = 0.001)], vitamin B12 [OR (95% CI) = 1.890 (1.393–2.565; p < 0.001], and homocysteine [OR (95% CI) = 0.191 (0.09–0.405; p < 0.001)] levels were associated with NTDs.

Conclusion

Folate and vitamin B12 are deficient in both cases and control mothers. The lower levels of folate and vitamin B12 with an elevated homocysteine level in NTD-affected pregnancy may be an indication that these biochemical variables were risk factors for NTDs. Folate/multivitamin supplementation and/or food fortification should be promoted.

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.

Prevalence of open neural tube defects and risk factors related to isolated anencephaly and spina bifida in live births from the "Dr. Juan I. Menchaca" Civil Hospital of Guadalajara (Jalisco, Mexico)

We determine the prevalence and trends of open neural tube defects (ONTDs) during 1991 to 2019 at the "Dr. Juan I. Menchaca" Civil Hospital of Guadalajara (Mexico). Also, details of potential risks were obtained in 662 newborns, including those 143 patients with anencephaly and open spina bifida (OSB) classified as isolated (cases) and 519 controls. Data were analyzed using multivariable logistic regression. Among 267 201 live births during the study period, 336 were born with ONTDs, yielding an overall prevalence of 12.6 per 10 000. After folic acid (FA)-related programs began in Mexico (2003-2019), only OSB showed a decline of 20.6%. For anencephaly, associated risks included relatives with neural tube defects (NTDs) (adjusted odds ratio [aOR]: 67.9, 95% confidence interval [95% CI]: 11.3-409.8), pre-pregnancy body mass index (BMI) ≥25 kg/m² (aOR: 2.6, 95% CI: 1.1-6.0), insufficient gestational weight gain (aOR: 3.0, 95% CI: 1.3-7.1), parity ≥4 (aOR: 3.2, 95% CI: 1.3-7.7), and exposure to analgesic/antipyretic drugs (aOR: 9.0; 95% CI: 2.5-33.0). For OSB, associated risks included consanguinity (aOR: 14.0, 95% CI: 3.5-55.9), relatives with NTDs (aOR: 22.4, 95% CI: 4.5-112.9), BMI ≥25 kg/m² (aOR: 2.5, 95% CI: 1.6-4.2), insufficient gestational weight gain (aOR: 1.9, 95% CI: 1.1-3.1), and exposures to hyperthermia (aOR: 2.3, 95% CI: 1.2-4.3), common cold (aOR: 6.8, 95% CI: 3.6-12.7), and analgesic/antipyretic drugs (aOR: 3.6, 95% CI: 1.3-10.0). Our high rate probably results from exposures to preventable risks, most related to FA, indicating a need for strengthening existing FA-related programs in Mexico.

Diet Alters Micronutrient Pathways in the Gut and Placenta that Regulate Fetal Growth and Development in Pregnant Mice

Maternal malnutrition and micronutrient deficiencies can alter fetal development. However, the mechanisms underlying these relationships are poorly understood. We used a systems physiology approach to investigate diet-induced effects on maternal gut microbes and folate/inositol transport in the maternal/fetal gut and placenta. Female mice were fed a control diet (CON) diet, undernourished (UN, restricted by 30% of CON intake) or a high-fat diet (HF, 60% kcals fat) during pregnancy to model normal pregnancy, fetal growth restriction or maternal metabolic dysfunction, respectively. At gestational day 18.5, we assessed circulating folate levels by microbiological assay, relative abundance of gut lactobacilli by G3PhyloChip™, and folate/inositol transporters in placenta and maternal/fetal gut by qPCR/immunohistochemistry. UN and HF-fed mothers had lower plasma folate concentrations vs. CON. Relative abundances of three lactobacilli taxa were higher in HF vs. UN and CON. HF-fed mothers had higher gut proton coupled folate transporter (Pcft) and reduced folate carrier 1 (Rfc1), and lower sodium myo-inositol co-transporter 2 (Smit2), mRNA expression vs. UN and CON. HF placentae had increased folate receptor beta (Frβ) expression vs. UN. mRNA expression of Pcft, folate receptor alpha (Frα), and Smit2 was higher in gut of HF fetuses vs. UN and CON. Transporter protein expression was not different between groups. Maternal malnutrition alters abundance of select gut microbes and folate/inositol transporters, which may influence maternal micronutrient status and delivery to the fetus, impacting pregnancy/fetal outcomes.

Understanding the Mothers of Children with Spina Bifida and Hydrocephalus in Tanzania

OBJECTIVE

To identify if there are cultural, medical, educational, economic, nutritional and geographic barriers to the prevention and treatment of spina bifida and hydrocephalus.

METHODS

The mothers of infants with spina bifida and hydrocephalus admitted to Muhimbilli Orthopaedic Institute, Dar Es Salaam, Tanzania, between 2013 and 2014 were asked to complete a questionnaire. A total of 299 infants were identified: 65 with myelomeningoceles, 19 with encephaloceles, and 215 with isolated hydrocephalus. The questionnaire was completed by 294 of the mothers.

RESULTS

There was a high variation in the geographic origin of the mothers. Approximately 85% traveled from outside of Dar Es Salaam. The mean age was 29 (15-45) years old with a parity of 3 (1-10). The rates of consanguinity, obesity, antiepileptic medication, HIV seropositivity, and family history were 2%, 13%, 0%, 2%, and 2%, respectively. A maize-based diet was found in 84%, and only 3% of woman took folic acid supplementation, despite 61% of mothers stating that they wished to conceive another baby. Unemployment was high (77%), a low level of education was common (76% not attended any school or obtaining a primary level only), and 20% were single mothers. Hospital only was the preferred method of treatment for 94% of the mothers, and 85% of the babies were born in a hospital.

CONCLUSIONS

Our study highlights some of the cultural, educational, geographic, nutritional, and economic difficulties in the prevention and management of spina bifida and hydrocephalus in Tanzania.

Closing in on Mechanisms of Open Neural Tube Defects

Neural tube defects (NTDs) represent a failure of the neural plate to complete the developmental transition to a neural tube. NTDs are the most common birth anomaly of the CNS. Following mandatory folic acid fortification of dietary grains, a dramatic reduction in the incidence of NTDs was observed in areas where the policy was implemented, yet the genetic drivers of NTDs in humans, and the mechanisms by which folic acid prevents disease, remain disputed. Here, we discuss current understanding of human NTD genetics, recent advances regarding potential mechanisms by which folic acid might modify risk through effects on the epigenome and transcriptome, and new approaches to study refined phenotypes for a greater appreciation of the developmental and genetic causes of NTDs.

Fetal surgical intervention for myelomeningocele: lessons learned, outcomes, and future implications

Fetal myelomeningocele (fMMC) closure (spina bifida aperta) has become a care option for patients that meet inclusion criteria, but it is clear that fetal intervention, while improving outcomes, is not a cure. This review will: (1) focus on the rationale for fMMC surgery based on preclinical studies and observations that laid the foundation for human pilot studies and a randomized controlled trial; (2) summarize important clinical outcomes; (3) discuss the feasibility, efficacy, and safety of recent developments in fetal surgical techniques and approaches; and (4) highlight future research directions. Given the increased risk of maternal and fetal morbidity associated with prenatal intervention, accompanied by the increasing number of centres performing interventions worldwide, teams involved in the care of these patients need to proceed with caution to maintain technical expertise, competency, and patient safety. Ongoing assessment of durability of the benefits of fMMC surgery, as well as additional refinement of patient selection criteria and counselling, is needed to further improve outcomes and reduce the risks to the mother and fetus. WHAT THIS PAPER ADDS: High-quality prospective studies are needed to broaden the indication for fetal surgery in the general myelomeningocele population. Innovative minimally invasive approaches have had promising results, yet lack comprehensive and robust experimental or clinical evaluation. Important information to help families make informed decisions regarding fetal surgery for myelomeningocele is provided.

Association between body mass index and folate insufficiency indicative of neural tube defects risk among nonpregnant women of childbearing age in the United States, NHANES, 2007-2010

BACKGROUND

Maternal folate status and obesity are known risk factors for neural tube defects (NTD) in the offspring. We examined the association between body mass index (BMI) categories and blood folate concentrations, specifically, red blood cell (RBC) folate concentrations indicative of NTD risk among nonpregnant women of child-bearing age (20-44 years) in the United States.

METHODS

We used data from 2007 to 2010 US National Health and Nutrition Examination Survey (NHANES). Overweight, obesity, and strata within obesity were examined. Serum and RBC folate concentrations were examined as continuous and categorical variables. RBC folate concentrations were grouped indicating high (≤585 nmol/L) and elevated risk (586-747 nmol/L) for NTDs. Unadjusted and adjusted prevalence odds ratios (aPOR) and their 95% confidence intervals (CI) were estimated using logistic regression.

RESULTS

Of the 30,878 participants, 25.6% were overweight, 32.7% obese, and 32.3% had RBC folate concentration indicating NTD risk (<748 nmol/L). Overweight was not associated with RBC folate level for NTD risk; however, a marginally significant negative association was noted for overall obesity and RBC folate concentrations indicative of elevated NTD risk (aPOR = 0.76; 95% CI = 0.45, 1.00). A significant protective association was noted between Class 3 obesity (BMI ≥40 kg/m² ) and folate concentration indicative of high NTD risk (≤585 nmol/L; aPOR = 0.46; 95% CI = 0.24, 0.89).

CONCLUSIONS

The prevalence of RBC folate concentrations indicating elevated or high NTD risk varied by level of obesity among nonpregnant women of child-bearing age. Further studies are needed to understand the folate pathway in overweight and obese women and subsequent NTD risk in their offspring.

Inflammatory Determinants of Pregravid Obesity in Placenta and Peripheral Blood

Pre-pregnancy (pregravid) obesity has been linked to several adverse health outcomes for both mother and offspring. Complications during pregnancy include increased risk for gestational diabetes, hypertension, preeclampsia, placental abruption, and difficulties during delivery. Several studies suggest that these negative outcomes are mediated by heightened systemic inflammation as well as changes in placental development and function. However, the molecular mechanisms by which pregravid obesity affects these processes are poorly understood. In this study, we aimed to address this question by carrying out a comprehensive analysis of the systemic maternal immune system coupled with placental gene expression and microbial profiling at term delivery (11 lean and 14 obese). Specifically, we examined the impact of pregravid obesity on circulating cytokines, chemokine, adipokines, and growth factors using multiplex Luminex assay. Innate and adaptive immune cell frequencies and their cytokine production in response to stimuli were measured using flow cytometry. Finally, changes in placental transcriptome and microbiome were profiled using RNA- and 16S-sequencing, respectively. Pregravid obesity is characterized by insulin and leptin resistance, high levels of circulating inflammatory markers IL-6 and CRP, in addition to chemokine IL-8 (p < 0.01). Moreover, pregravid obesity was associated with lower frequency of naïve CD4+ T-cells (p < 0.05), increased frequency of memory CD4+ T-cells (p < 0.01), and a shift towards Th2 cytokine production (p = 0.05). Myeloid cells from the obese cohort produced higher levels of pro-inflammatory cytokines but lower levels of chemokines following TLR stimulation (p < 0.05). Lastly, pregravid obesity is associated with increased abundance of Bacteroides and changes in the expression of genes important for nutrient transport and immunity (FDR < 0.05). Collectively, these data indicate that pregravid obesity is associated with heightened systemic inflammation and of dysregulated nutrient transport in the placenta and provide insight into the basis of fetal reprogramming.

Population-based case-control study of the association between weather-related extreme heat events and neural tube defects

BACKGROUND

Elevated body core temperature has been shown to have teratogenic effects in animal studies. Our study evaluated the association between weather-related extreme heat events (EHEs) in the summer season and neural tube defects (NTDs), and further investigated whether pregnant women with a high pregestational body mass index (BMI) have a greater risk of having a child with NTDs associated with exposure to EHE than women with a normal BMI.

METHODS

We conducted a population-based case-control study among mothers of infants with NTDs and mothers of infants without major birth defects, who participated in the National Birth Defects Prevention Study and had at least 1 day of the third or fourth week postconception during summer months. EHEs were defined using the 95^th and the 90^th percentiles of the daily maximum universal apparent temperature. Adjusted odds ratios and 95% confidence intervals were calculated using unconditional logistic regression models with Firth's penalized likelihood method while controlling for other known risk factors.

RESULTS

Overall, we did not observe a significant association between EHEs and NTDs. At the climate region level, consistently elevated but not statistically significant estimates were observed for at least 2 consecutive days with daily universal apparent maximum temperature above the 95^th percentile of the UATmax distribution for the season, year, and weather monitoring station in New York (Northeast), North Carolina and Georgia (Southeast), and Iowa (Upper Midwest). No effect modification by BMI was observed.

CONCLUSION

EHEs occurring during the relevant developmental window of embryogenesis do not appear to appreciably affect the risk of NTDs. Future studies should refine exposure assessment, and more completely account for maternal activities that may modify the effects of weather exposure. Birth Defects Research 109:1482-1493, 2017.© 2017 Wiley Periodicals, Inc.

Maternal obesity and the risk of neural tube defects in offspring: A meta-analysis

OBJECTIVES

The aim of this was to access maternal obesity and the risk of neural tube defects (NTDs) in offspring, and establishes a nonlinear dose-response relationship between maternal body mass index (BMI) and risk of NTDs in offspring.

METHODS

PubMed and Web of Science were systematically searched. We compared NTDs risk difference in maternal obesity group vs. normal weight group+overweight group, and maternal obesity group vs. normal weight group. We also examined the dose-response relationship between maternal body mass index and the risk of NTDs in offspring.

RESULTS

A total of 22 studies with 1,758,832 patients included in the meta-analysis. The results showed obesity maternal obesity is an important risk factor for NTDs in offspring. When maternal obesity group compared with normal weight group+overweight group, the summary OR of NTDs was 1.632 (95% CI 1.473-1.808; Z=9.37, P<0.00001); when maternal obesity group compared with normal weight group, the summary OR was 1.682 (95% CI 1.510-1.873; Z=9.44, P<0.00001). No publication biases were found. Dose-response meta-analysis showed statistically significant association between maternal BMI and risk of NTDs in offspring (model χ²=41.49, <0.00001). In linear model, the OR of NTDs in offspring was 1.040 (95% CI 1.027-1.051) for every 1kg/m² BMI increase in mother. In spline model, the OR of NTDs in offspring risk increased rapidly along with maternal BMI, especially when BMI >30kg/m². Sensitivity analyses by only included the studies reported adjusted OR showed the result was robust.

CONCLUSION

Our meta-analysis indicated that maternal obesity is an important risk factor for neural tube defects in offspring.

On the track to adulthood: the missions of the young human being, dodging the risks and gaining the tools

Medical staff are expected to cooperate with other professions and agencies in helping the young human in achieving the goal of becoming a healthy, well- functioning adult that expresses her/his maximal potential. Achieving this goal should be cost-effective. Cost includes not just the economic burden but also psychosocial determinants such as emotional disruption, stress, living at risk, malfunctioning, and dependency. Acknowledging the risks and the expected achievements at each age are useful in analyzing the failure of community health programs and in planning preventive modalities and needed remedies.

Pregestational Obesity-Induced Embryopathy

INTRODUCTION

Several epidemiologic studies in humans have shown a relationship between pregestational obesity and congenital malformations in offsprings. However, there are no experimental evidence in animal models of obesity and pregnancy that reproduce the teratogenesis induced by this pathological condition.

OBJECTIVE

To evaluate the effect of monosodium glutamate-induced obesity on embryonic development.

METHODS

Female rats received subcutaneously (4 mg/g body weight) monosodium glutamate (MSG) solution or saline solution 0.9% (vehicle control) at days 2, 4, 6, 8, and 10 of life. At 90 days of age, all animals were mated, and on day 11 of pregnancy, the animals were killed. Biochemical variables (glucose, triglycerides, total cholesterol, and insulin) were determined in plasma of dams and embryo homogenates (DNA and protein content, advanced oxidation protein products). Embryos were evaluated for malformations, crown-rump length, and somite number.

RESULTS

Obese rats presented higher triglyceride levels as compared to nonobese rats. Increased proportion of malformed embryos, decreased crown-rump length, somite number, DNA, and protein content were observed in offspring of obese rats.

CONCLUSION

The model of obesity induced with MSG reproduces the maternal obesity-induced teratogenesis. The hypertriglyceridemia observed in MSG obese pregnant rats could be related to increased birth defect.

Serum and red-blood-cell folate demonstrate differential associations with BMI in pregnant women

Objective

To examine the association between BMI and folate concentrations in serum and red blood cells (RBC) in pregnant women.

Design

A cross-sectional comparison of folate concentrations in serum and RBC sampled simultaneously from the same individual.

Setting

The Ottawa Hospital and Kingston General Hospital, Ontario, Canada.

Subjects

Pregnant women recruited between 12 and 20 weeks of gestation.

Results

A total of 869 pregnant women recruited from April 2008 to April 2009 were included in the final analysis. Serum folate was inversely associated and RBC folate positively associated with BMI, after adjusting for folic acid supplementation, age, gestational age at blood sample collection, race, maternal education, annual income, smoking and MTHFR 677C→T genotype. In stratified analyses, this differential association was significant in women with the MTHFR CC variant. In women with the CT and TT variants, the differential associations were in the same direction but not significant. Folic acid supplementation during pregnancy did not alter the differential association of BMI with serum and RBC folate concentration. This indicates that the current RBC folate cut-off approach for assessing risk of neural tube defects in obese women may be limited.

Conclusions

BMI is inversely associated with serum folate and positively associated with RBC folate in pregnant women, especially for those with the MTHFR CC variant.

Parturition dysfunction in obesity: time to target the pathobiology

Over a third of women of childbearing age in the United States are obese, and during pregnancy they are at increased risk for delayed labor onset and slow labor progress that often results in unplanned cesarean delivery. The biology behind this dysfunctional parturition is not well understood. Studies of obesity-induced changes in parturition physiology may facilitate approaches to optimize labor in obese women. In this review, we summarize known and proposed biologic effects of obesity on labor preparation, contraction/synchronization, and endurance, drawing on both clinical observation and experimental data. We present evidence from human and animal studies of interactions between obesity and parturition signaling in all elements of the birth process, including: delayed cervical ripening, prostaglandin insensitivity, amniotic membrane strengthening, decreased myometrial oxytocin receptor expression, decreased myocyte action potential initiation and contractility, decreased myocyte gap junction formation, and impaired myocyte neutralization of reactive oxygen species. We found convincing clinical data on the effect of obesity on labor initiation and successful delivery, but few studies on the underlying pathobiology. We suggest research opportunities and therapeutic interventions based on plausible biologic mechanisms.

The impact of maternal obesity during pregnancy on offspring immunity

In the United States, approximately 64% of women of childbearing age are either overweight or obese. Maternal obesity during pregnancy is associated with a greater risk for adverse maternal-fetal outcomes. Adverse health outcomes for the offspring can persist into adulthood, increasing the incidence of several chronic conditions including cardiovascular disease, diabetes, and asthma. Since these diseases have a significant inflammatory component, these observations are indicative of perturbation of the normal development and maturation of the immune system of the offspring in utero. This hypothesis is strongly supported by data from several rodent studies. Although the mechanisms of these perturbations are not fully understood, it is thought that increased placental inflammation due to obesity may directly affect neonatal development through alterations in nutrient transport. In this review we examine the impact of maternal obesity on the neonatal immune system, and potential mechanisms for the changes observed.

Risks associated with obesity in pregnancy, for the mother and baby: a systematic review of reviews

Maternal obesity is linked with adverse outcomes for mothers and babies. To get an overview of risks related to obesity in pregnant women, a systematic review of reviews was conducted. For inclusion, reviews had to compare pregnant women of healthy weight with women with obesity, and measure a health outcome for mother and/or baby. Authors conducted full-text screening, quality assurance using the AMSTAR tool and data extraction steps in pairs. Narrative analysis of the 22 reviews included show gestational diabetes, pre-eclampsia, gestational hypertension, depression, instrumental and caesarean birth, and surgical site infection to be more likely to occur in pregnant women with obesity compared with women with a healthy weight. Maternal obesity is also linked to greater risk of preterm birth, large-for-gestational-age babies, foetal defects, congenital anomalies and perinatal death. Furthermore, breastfeeding initiation rates are lower and there is greater risk of early breastfeeding cessation in women with obesity compared with healthy weight women. These adverse outcomes may result in longer duration of hospital stay, with concomitant resource implications. It is crucial to reduce the burden of adverse maternal and foetal/child outcomes caused by maternal obesity. Women with obesity need support to lose weight before they conceive, and to minimize their weight gain in pregnancy.

Association of facilitated glucose transporter 2 gene variants with the myelomeningocele phenotype

BACKGROUND

Neural tube defects (NTDs) remain the second most common cause of congenital malformations. Myelomeningocele (MM), the most common NTD compatible with survival, results from genetic and environmental factors. Epidemiologic studies and murine models support the hypotheses that obesity, diabetes and hyperglycemia confer increased risk of NTDs. Presence of wild-type facilitated glucose transporter, Glut2, in mouse embryos has been shown to increase risk for NTDs in hyperglycemic pregnancy.

METHODS

The GLUT2 gene of 96 MM patients was amplified, sequenced and compared with the reference sequence (NM_000340). Variants previously unreported in the single nucleotide polymorphisms (SNP) database were considered novel. Allele frequencies of reported SNPs were compared with reference populations using Fisher's exact test.

RESULTS

Analysis revealed three novel variants: a substitution in the core promoter region (c.-331c>t), a substitution (c.-182g>a) in the 5'-untranslated region, and a single base pair deletion (c.1441delT) in the coding sequences. Polymorphic alleles for 10 SNPs were also identified. Seven SNPs are significantly associated with MM in the Mexican American patients tested (p < 0.05) and two of the seven remained significant after Bonferroni correction.

CONCLUSION

We identified three novel variants and seven SNPs associated with MM. The novel variants in the core promoter and in the 5'-untranslated region could affect GLUT2 mRNA transcription and stability and translation efficiency. The c.1441delT variant is predicted to alter the reading frame and prematurely terminate translation of the GLUT2 protein at the C-terminus, affecting GLUT2 protein function. Presence of GLUT2 variants may disrupt GLUT2 activity and influence MM susceptibility.

Population red blood cell folate concentrations for prevention of neural tube defects: Bayesian model

OBJECTIVE

To determine an optimal population red blood cell (RBC) folate concentration for the prevention of neural tube birth defects.

DESIGN

Bayesian model.

SETTING

Data from two population based studies in China.

PARTICIPANTS

247,831 participants in a prospective community intervention project in China (1993-95) to prevent neural tube defects with 400 μg/day folic acid supplementation and 1194 participants in a population based randomized trial (2003-05) to evaluate the effect of folic acid supplementation on blood folate concentration among Chinese women of reproductive age.

INTERVENTION

Folic acid supplementation (400 μg/day).

MAIN OUTCOME MEASURES

Estimated RBC folate concentration at time of neural tube closure (day 28 of gestation) and risk of neural tube defects.

RESULTS

Risk of neural tube defects was high at the lowest estimated RBC folate concentrations (for example, 25.4 (95% uncertainty interval 20.8 to 31.2) neural tube defects per 10,000 births at 500 nmol/L) and decreased as estimated RBC folate concentration increased. Risk of neural tube defects was substantially attenuated at estimated RBC folate concentrations above about 1000 nmol/L (for example, 6 neural tube defects per 10,000 births at 1180 (1050 to 1340) nmol/L). The modeled dose-response relation was consistent with the existing literature. In addition, neural tube defect risk estimates developed using the proposed model and population level RBC information were consistent with the prevalence of neural tube defects in the US population before and after food fortification with folic acid.

CONCLUSIONS

A threshold for "optimal" population RBC folate concentration for the prevention of neural tube defects could be defined (for example, approximately 1000 nmol/L). Population based RBC folate concentrations, as a biomarker for risk of neural tube defects, can be used to facilitate evaluation of prevention programs as well as to identify subpopulations at elevated risk for a neural tube defect affected pregnancy due to folate insufficiency.

Dietary folate intake levels in rural women immediately before pregnancy in Northern China

BACKGROUND

The study aims to assess dietary folate levels and food sources in women immediately before pregnancy in a rural area of northern China associated with a high prevalence of neural tube defects.

METHODS

Information was collected by face-to-face interviews with women who sought premarital healthcare and planned to become pregnant within the next 12 months from November 2009 through December 2012. Information regarding food consumption was obtained by means of 24-hr dietary recall. Folate values were assigned to foods according to the China Food Composition 2004. Factors associated with dietary folate intake were analyzed by multiple linear regression.

RESULTS

Mean (± standard deviation) and median (interquartile range) daily folate intake levels were 114.3 ± 59.7 and 102.8 (69.3-146.8) μg/day, respectively. Over 99% of the subjects had an intake level below 320 μg/day, the estimated average requirement for nonpregnant women. Only 1% and 7% of the women consumed 75% and 50%, respectively, of the recommended daily folate intake of 400 μg for nonpregnant women. Over 80% of total folate consumption came from cereals, vegetables, and tubers, whereas fruit consumption was severely lacking. Underweight women, farmers, women enrolled during the winter, and women with access to fewer food types or daily meals were more likely to exhibit low folate intake levels.

CONCLUSION

Dietary folate intake among study participants was far below the recommended intake level. Folic acid fortification of cereals is advised to raise folate intake in rural Chinese women planning to become pregnant.

Neural tube defects, folic acid and methylation

Neural tube defects (NTDs) are common complex congenital malformations resulting from failure of the neural tube closure during embryogenesis. It is established that folic acid supplementation decreases the prevalence of NTDs, which has led to national public health policies regarding folic acid. To date, animal studies have not provided sufficient information to establish the metabolic and/or genomic mechanism(s) underlying human folic acid responsiveness in NTDs. However, several lines of evidence suggest that not only folates but also choline, B12 and methylation metabolisms are involved in NTDs. Decreased B12 vitamin and increased total choline or homocysteine in maternal blood have been shown to be associated with increased NTDs risk. Several polymorphisms of genes involved in these pathways have also been implicated in risk of development of NTDs. This raises the question whether supplementation with B12 vitamin, betaine or other methylation donors in addition to folic acid periconceptional supplementation will further reduce NTD risk. The objective of this article is to review the role of methylation metabolism in the onset of neural tube defects.

Maternal body mass index and the association between folic acid supplements and neural tube defects

AIM

To study the influence of maternal body mass index (BMI) on the association between folic acid supplementation and neural tube defects (NTDs) risk in offspring.

METHODS

A hospital-based, case-control study was conducted between 2006 and 2008 on 459 mothers with NTDs-affected births and 459 mothers without NTDs-affected births. Logistic regression models examined the associations between folic acid supplementation and the NTDs risk in offspring for all mothers, underweight/normal weight mothers (BMI<24.0) and overweight/obese mothers (BMI ≥24.0). The effects were evaluated by adjusted odds ratio (AOR) and 95% confidence intervals (CIs) with SAS 9.1.3 software.

RESULTS

The overall AOR for periconceptional folic acid supplementation was 0.315 (95% CI = 0.172-0.577) when compared with no supplements. Stratified by maternal BMI, the AOR for periconceptional folic acid supplementation in overweight/obese mothers was greater than in underweight/normal weight mothers (0.646 vs. 0.208). The AOR for folic acid supplementation within 3 months before conception was 0.711 (95% CI = 0.323-1.563) in all mothers. Stratified by maternal BMI, the AOR for folic acid supplementation within 3 months before conception in overweight/obese mothers was greater than in underweight/normal weight mothers (0.658 vs. 0.527).

CONCLUSION

The association between folic acid supplementation and the reduced NTDs risk was weaker in overweight/obese mothers (BMI ≥24.0) than in underweight/normal weight mothers (BMI <24.0).