Prevention of neural-tube defects with folic acid in China. China-U.S. Collaborative Project for Neural Tube Defect Prevention

Biomarkers of Nutrition for Development-Folate Review

The Biomarkers of Nutrition for Development (BOND) project is designed to provide evidence-based advice to anyone with an interest in the role of nutrition in health. Specifically, the BOND program provides state-of-the-art information and service with regard to selection, use, and interpretation of biomarkers of nutrient exposure, status, function, and effect. To accomplish this objective, expert panels are recruited to evaluate the literature and to draft comprehensive reports on the current state of the art with regard to specific nutrient biology and available biomarkers for assessing nutrients in body tissues at the individual and population level. Phase I of the BOND project includes the evaluation of biomarkers for 6 nutrients: iodine, iron, zinc, folate, vitamin A, and vitamin B-12. This review represents the second in the series of reviews and covers all relevant aspects of folate biology and biomarkers. The article is organized to provide the reader with a full appreciation of folate's history as a public health issue, its biology, and an overview of available biomarkers (serum folate, RBC folate, and plasma homocysteine concentrations) and their interpretation across a range of clinical and population-based uses. The article also includes a list of priority research needs for advancing the area of folate biomarkers related to nutritional health status and development.

Patterns of folic acid use in pregnant Saudi women and prevalence of neural tube defects - Results from a nested case-control study

BACKGROUND

Although the role of folic acid (FA) in preventing neural tube defects (NTDs) is well documented, its optimal intake in pregnant women is still low in many countries. Here, we prospectively studied the prevalence of NTDs in the newborns and the patterns of FA intake in pregnant Saudi mothers.

METHODS

This case-control study was nested within a 3-year project (July 2010 to June 2013) to study the patterns of birth defects in the offspring of Saudi women who received their antenatal care and delivered at Prince Sultan Military Medical City, Riyadh-Saudi Arabia. Enrolled mothers were divided into 4 groups: group 1 (FA taken before pregnancy and continued regularly after conception), group 2 (FA taken post-conception), group 3 (no FA intake), and group 4 (did not remember or were unsure of taking FA). Control mothers were randomly selected from those with normal first obstetrical ultrasound scan at 18-22 weeks of gestation.

RESULTS

The cohort included 30,531 mothers giving birth to 28,646 infants. We studied 1179 mothers of babies with birth defects (BDs) and 1262 control mothers. There were 237 (9.7%) mothers in-group 1; 2001 (82%) in-group 2; 154 (6.3%) in-group 3; and 49 (2%) in-group 4. There were 49 babies with NTDs, a prevalence of 1.7/1000 total births. Among the studied mothers 2274 (93%) took FA either full or partial course.

CONCLUSION

The high prevalence of NTDs and the low optimal FA intake highlight the need for a strict implementation of staple food fortification and health education program for Saudi women.

Global implementation of genomic medicine: We are not alone

Around the world, innovative genomic-medicine programs capitalize on singular capabilities arising from local health care systems, cultural or political milieus, and unusual selected risk alleles or disease burdens. Such individual efforts might benefit from the sharing of approaches and lessons learned in other locales. The U.S. National Human Genome Research Institute and the National Academy of Medicine recently brought together 25 of these groups to compare projects, to examine the current state of implementation and desired near-term capabilities, and to identify opportunities for collaboration that promote the responsible practice of genomic medicine. Efforts to coalesce these groups around concrete but compelling signature projects should accelerate the responsible implementation of genomic medicine in efforts to improve clinical care worldwide.

Folate and Vitamin B12 Status in Latin America and the Caribbean

Background:

The current magnitude of folate and vitamin B12 deficiency in Latin America and the Caribbean is uncertain.

Objective:

To summarize data on plasma or serum vitamin B12 and folate concentrations in Latin America and the Caribbean reported since 1990, a period that covers the era before and after the introduction of folic acid fortification.

Methods:

A systematic review was conducted in 2012 and updated in 2014. Studies and surveys using biochemical biomarkers and conducted in apparently healthy individuals were identified.

Results:

Folate deficiency in Latin America and the Caribbean appears not to be a public health problem (prevalence < 5%) after the introduction of folic acid fortification. However, there is some indication that high rates of low or marginal vitamin B12 status remain in most locations and across population groups.

Conclusions:

Adding vitamin B12 as a fortificant with folic acid may be the best strategy in areas where vitamin B12 deficiency is an established concern.

U.S. women of childbearing age who are at possible increased risk of a neural tube defect-affected pregnancy due to suboptimal red blood cell folate concentrations, National Health and Nutrition Examination Survey 2007 to 2012

BACKGROUND

Red blood cell (RBC) folate concentrations are a potential biomarker of folate-sensitive neural tube defect (NTD) risk in the population. The purpose of this analysis was to describe women in the U.S. population with RBC folate concentrations below those associated with optimal NTD prevention.

METHODS

We used data from the 2007 to 2012 National Health and Nutrition Examination Survey (NHANES) to assess the RBC folate status of U.S. women of childbearing age relative to risk categories for NTD risk based on RBC folate concentrations. We defined suboptimal RBC folate concentrations as those associated with a prevalence of ≥9 NTDs per 10,000 live births.

RESULTS

Among nonpregnant women age 12 to 49 years, 22.8% (95% Confidence Interval: 21.1, 24.6) had suboptimal RBC folate concentrations. Women had greater odds of having a suboptimal RBC folate concentration if they did not use dietary supplements containing folic acid; had mandatorily fortified enriched cereal grain products as their only source of folic acid; were non-Hispanic black or Hispanic; or were current smokers.

CONCLUSION

Based on RBC folate concentrations, we would predict that the majority of U.S. women of reproductive age are not at increased risk for folate sensitive NTDs in the presence of mandatory folic acid fortification. Prevention policies and programs can be aimed at population subgroups identified as having higher predicted risk for folate-sensitive NTDs based on RBC folate concentrations.

Assessing the association between the methylenetetrahydrofolate reductase (MTHFR) 677C>T polymorphism and blood folate concentrations: a systematic review and meta-analysis of trials and observational studies

BACKGROUND

The methylenetetrahydrofolate reductase (MTHFR) 677C>T polymorphism is a risk factor for neural tube defects. The T allele produces an enzyme with reduced folate-processing capacity, which has been associated with lower blood folate concentrations.

OBJECTIVE

We assessed the association between MTHFR C677T genotypes and blood folate concentrations among healthy women aged 12-49 y.

DESIGN

We conducted a systematic review of the literature published from January 1992 to March 2014 to identify trials and observational studies that reported serum, plasma, or red blood cell (RBC) folate concentrations and MTHFR C677T genotype. We conducted a meta-analysis for estimates of percentage differences in blood folate concentrations between genotypes.

RESULTS

Forty studies met the inclusion criteria. Of the 6 studies that used the microbiologic assay (MA) to measure serum or plasma (S/P) and RBC folate concentrations, the percentage difference between genotypes showed a clear pattern of CC > CT > TT. The percentage difference was greatest for CC > TT [S/P: 13%; 95% credible interval (CrI): 7%, 18%; RBC: 16%; 95% CrI: 12%, 20%] followed by CC > CT (S/P: 7%; 95% CrI: 1%, 12%; RBC: 8%; 95% CrI: 4%, 12%) and CT > TT (S/P: 6%; 95% CrI: 1%, 11%; RBC: 9%; 95% CrI: 5%, 13%). S/P folate concentrations measured by using protein-binding assays (PBAs) also showed this pattern but to a greater extent (e.g., CC > TT: 20%; 95% CrI: 17%, 22%). In contrast, RBC folate concentrations measured by using PBAs did not show the same pattern and are presented in the Supplemental Material only.

CONCLUSIONS

Meta-analysis results (limited to the MA, the recommended population assessment method) indicated a consistent percentage difference in S/P and RBC folate concentrations across MTHFR C677T genotypes. Lower blood folate concentrations associated with this polymorphism could have implications for a population-level risk of neural tube defects.

Awareness of folic acid use increases its consumption, and reduces the risk of spina bifida

The majority of neural tube defects were believed to be folic acid (FA)-preventable in the 1990s. The Japanese government recommended women planning pregnancy to take FA supplements of 400 μg/d in 2000, but the incidence of spina bifida has not decreased. We aimed to evaluate the OR of having an infant with spina bifida for women who periconceptionally took FA supplements and the association between an increase in supplement use and possible promoters for the increase. This is a case-control study which used 360 case women who gave birth to newborns afflicted with spina bifida, and 2333 control women who gave birth to healthy newborns during the first 12 years of this century. They were divided into two 6-year periods; from 2001 to 2006 and from 2007 to 2012. Logistic regression analyses were conducted to compute OR between cases and controls. The adjusted OR of having an infant with spina bifida for supplement users was 0.48 in the first period, and 0.53 in the second period. The proportion of women who periconceptionally consumed supplements significantly increased from 10 % in the first period to 30 % in the second period. Awareness of the preventive role of FA was a promoter for an increase in supplement use, and thus an FA campaign in high school seems rational and effective. The failure of the current public health policy is responsible for an epidemic of spina bifida. Mandatory food fortification with FA is urgent and long overdue in Japan.

Maternal obesity, caesarean delivery and caesarean delivery on maternal request: a cohort analysis from China

BACKGROUND

To quantify the association between maternal obesity and caesarean delivery, particularly caesarean delivery on maternal request (CDMR), a fast-growing component of caesarean delivery in many nations.

METHODS

We followed 1,019,576 nulliparous women registered in the Perinatal Healthcare Surveillance System during 1993-2010. Maternal body mass index (BMI, kg/m(2) ), before pregnancy or during early pregnancy, was classified as underweight (<18.5), normal (18.5 to <23; reference), overweight (23 to <27.5), or obese (≥27.5), consistent with World Health Organization guidelines for Asian people. The association between maternal obesity and overall caesarean and its subtypes was modelled using log-binomial regression.

RESULTS

During the 18-year period, 404,971 (39.7%) caesareans and 93,927 (9.2%) CDMRs were identified. Maternal obesity was positively associated with overall caesarean and CDMR. Adjusted risk ratios for overall caesarean in the four ascending BMI categories were 0.96 [95% confidence interval (CI) 0.94, 0.97], 1.00 (Reference), 1.16 [95% CI 1.14, 1.18], 1.39 [95% CI 1.43, 1.54], and for CDMR were 0.95 [95% CI 0.94, 0.96], 1.00 (Reference), 1.20 [95% CI 1.18, 1.22], 1.48 [95% CI 1.433, 1.54]. Positive associations were consistently found in women residing in southern and northern provinces and in subgroups stratified by year of delivery, urban or rural residence, maternal age, education, level of delivering hospital, and birthweight.

CONCLUSIONS

In a large Chinese cohort study, maternal obesity was associated with an increased risk of caesarean delivery and its subtypes, including CDMR. Given the rising global prevalence of obesity, and in view of the growth of CDMR, it seems likely that caesarean births will increase, unless there are changes in obstetrical practice.

Assessing the association between natural food folate intake and blood folate concentrations: a systematic review and Bayesian meta-analysis of trials and observational studies

Folate is found naturally in foods or as synthetic folic acid in dietary supplements and fortified foods. Adequate periconceptional folic acid intake can prevent neural tube defects. Folate intake impacts blood folate concentration; however, the dose-response between natural food folate and blood folate concentrations has not been well described. We estimated this association among healthy females. A systematic literature review identified studies (1 1992-3 2014) with both natural food folate intake alone and blood folate concentration among females aged 12-49 years. Bayesian methods were used to estimate regression model parameters describing the association between natural food folate intake and subsequent blood folate concentration. Seven controlled trials and 29 observational studies met the inclusion criteria. For the six studies using microbiologic assay (MA) included in the meta-analysis, we estimate that a 6% (95% Credible Interval (CrI): 4%, 9%) increase in red blood cell (RBC) folate concentration and a 7% (95% CrI: 1%, 12%) increase in serum/plasma folate concentration can occur for every 10% increase in natural food folate intake. Using modeled results, we estimate that a natural food folate intake of ≥ 450 μg dietary folate equivalents (DFE)/day could achieve the lower bound of an RBC folate concentration (~ 1050 nmol/L) associated with the lowest risk of a neural tube defect. Natural food folate intake affects blood folate concentration and adequate intakes could help women achieve a RBC folate concentration associated with a risk of 6 neural tube defects/10,000 live births.

Folic acid in pregnancy and mortality from cancer and cardiovascular disease: further follow-up of the Aberdeen folic acid supplementation trial

Background

Supplemental periconceptional folic acid is recommended to reduce the risk of fetal neural tube defects. A previous report indicated an elevated risk of breast cancer and all cancer deaths in later life among women randomised by alternate allocation to high-dose (5 mg/day) folic acid in pregnancy compared with placebo; however, findings were based on small numbers of cases. Our aim was to extend the previous analysis by including data from an additional 10 years of follow-up.

Methods

Records of participants in a large (n=2928) trial of folate supplementation (5 or 0.2 mg folic acid, or placebo) in pregnancy in the 1960s were linked to central registries in Scotland. Unadjusted and adjusted HRs were calculated for all-cause, cardiovascular, all cancer and breast cancer mortality, and all cancer and breast cancer morbidity. Analyses were done using (1) data from the time of the previous linkage (2002) to March 2013; and (2) data from 1980 to March 2013.

Results

There was no evidence to suggest an excess risk of morbidity or mortality in either supplementation group compared with placebo for 2002–2013 and no associations were seen for the full time period (1980–2013).

Conclusions

Findings from this extended follow-up do not support our previous observation of an elevated risk of mortality from breast cancer or all cancers in later life among women who had taken 5 mg folic acid/day during pregnancy. Furthermore, there were no associations with risk of mortality from all-causes, all cancers or cardiovascular disease.

Consequences of dietary methyl donor supplements: Is more always better?

Epigenetic mechanisms are now recognized to play roles in disease etiology. Several diseases increasing in frequency are associated with altered DNA methylation. DNA methylation is accomplished through metabolism of methyl donors such as folate, vitamin B12, methionine, betaine (trimethylglycine), and choline. Increased intake of these compounds correlates with decreased neural tube defects, although this mechanism is not well understood. Consumption of these methyl donor pathway components has increased in recent years due to fortification of grains and high supplemental levels of these compounds (e.g. vitamins, energy drinks). Additionally, people with mutations in one of the enzymes that assists in the methyl donor pathway (5-MTHFR) are directed to consume higher amounts of methyl donors to compensate. Recent evidence suggests that high levels of methyl donor intake may also have detrimental effects. Individualized medicine may be necessary to determine the appropriate amounts of methyl donors to be consumed, particularly in women of child bearing age.

Maternal dietary uridine causes, and deoxyuridine prevents, neural tube closure defects in a mouse model of folate-responsive neural tube defects

BACKGROUND

Folic acid prevents neural tube closure defects (NTDs), but the causal metabolic pathways have not been established. Serine hydroxymethyltransferase 1 (SHMT1) is an essential scaffold protein in folate-dependent de novo thymidylate synthesis in the nucleus. SHMT1-deficient mice provide a model to investigate folic acid-responsive NTDs wherein disruption of de novo thymidylate synthesis impairs neural tube closure.

OBJECTIVE

We examined the effects of maternal supplementation with the pyrimidine nucleosides uridine, thymidine, or deoxyuridine with and without folate deficiency on NTD incidence in the Shmt1 mouse model.

DESIGN

Shmt1(+/+) and Shmt1(-/-) female mice fed folate-replete or folate-deficient diets and supplemented with uridine, thymidine, or deoxyuridine were bred, and litters (n = 10-23 per group) were examined for the presence of NTDs. Biomarkers of impaired folate status and metabolism were measured, including plasma nucleosides, hepatic uracil content, maternal plasma folate concentrations, and incorporation of nucleoside precursors into DNA.

RESULTS

Shmt1(+/-) and Shmt1(-/-) embryos from dams fed the folate-deficient diet were susceptible to NTDs. No NTDs were observed in litters from dams fed the folate-deficient diet supplemented with deoxyuridine. Surprisingly, uridine supplementation increased NTD incidence, independent of embryo genotype and dietary folic acid. These dietary nucleosides did not affect maternal hepatic uracil accumulation in DNA but did affect plasma folate concentrations.

CONCLUSIONS

Maternal deoxyuridine supplementation prevented NTDs in dams fed the folate-deficient diet, whereas maternal uridine supplementation increased NTD incidence, independent of folate and embryo genotype. These findings provide new insights into the metabolic impairments and mechanisms of folate-responsive NTDs resulting from decreased Shmt1 expression.

Variants in maternal COMT and MTHFR genes and risk of neural tube defects in offspring

Methylenetetrahydrofolate reductase (MTHFR) C677T and catechol-O-Methyltransferase (COMT) G158A are associated with a risk of neural tube defects (NTDs) in offspring. This study examined the effect of a MTHFR × COMT interaction on the risk of NTDs in a Chinese population with a high prevalence of NTDs. A total of 576 fetuses or newborns with NTDs and 594 controls were genotyped for MTHFRrs1801133, MTHFRrs1801131, and COMTrs4680 and COMTrs737865. Information on maternal sociodemographic characteristics, reproductive history, and related behavior was collected through face-to-face interviews. Possible interactions between genetic variants of MTHFR and COMT were examined. MTHFR C677T homozygous TT was associated with an elevated risk of total NTDs (odds ratio [OR] = 1.37, 95 % confidence interval [CI] = 0.93-2.03) and of anencephaly (OR = 1.67, 95 % CI = 0.98-2.84) compared with the CC genotype. There was a COMT rs737865 CC × MTHFR rs1801133 TT interaction for total NTDs (OR = 3.02, 95 % CI = 1.00-9.14) and for anencephaly (OR = 3.39, 95 % CI = 0.94-12.18). No interaction was found between COMT rs4680 AA/AG and MTHFR CT/TT genotypes for total NTDs or any subtype of NTD. The interaction of COMT rs737865 and MTHFR C677T was associated with an increased risk of NTDs, especially anencephaly, in a Chinese population with a high prevalence of NTDs.

Neural tube defects

Neural tube defects (NTDs), including spina bifida and anencephaly, are severe birth defects of the central nervous system that originate during embryonic development when the neural tube fails to close completely. Human NTDs are multifactorial, with contributions from both genetic and environmental factors. The genetic basis is not yet well understood, but several nongenetic risk factors have been identified as have possibilities for prevention by maternal folic acid supplementation. Mechanisms underlying neural tube closure and NTDs may be informed by experimental models, which have revealed numerous genes whose abnormal function causes NTDs and have provided details of critical cellular and morphological events whose regulation is essential for closure. Such models also provide an opportunity to investigate potential risk factors and to develop novel preventive therapies.

Genomic DNA hypomethylation is associated with neural tube defects induced by methotrexate inhibition of folate metabolism

DNA methylation is thought to be involved in the etiology of neural tube defects (NTDs). However, the exact mechanism between DNA methylation and NTDs remains unclear. Herein, we investigated the change of methylation in mouse model of NTDs associated with folate dysmetabolism by use of ultraperformance liquid chromatography tandem mass spectrometry (UPLC/MS/MS), liquid chromatography-electrospray ionization tandem mass spectrometry (LC-MS/MS), microarray, matrix-assisted laser desorption/ionization time-of-flight mass spectrometry and Real time quantitative PCR. Results showed that NTD neural tube tissues had lower concentrations of 5-methyltetrahydrofolate (5-MeTHF, P = 0.005), 5-formyltetrahydrofolate (5-FoTHF, P = 0.040), S-adenosylmethionine (SAM, P = 0.004) and higher concentrations of folic acid (P = 0.041), homocysteine (Hcy, P = 0.006) and S-adenosylhomocysteine (SAH, P = 0.045) compared to control. Methylation levels of genomic DNA decreased significantly in the embryonic neural tube tissue of NTD samples. 132 differentially methylated regions (35 low methylated regions and 97 high methylated regions) were selected by microarray. Two genes (Siah1b, Prkx) in Wnt signal pathway demonstrated lower methylated regions (peak) and higher expression in NTDs (P<0.05; P<0.05). Results suggest that DNA hypomethylation was one of the possible epigenetic variations correlated with the occurrence of NTDs induced by folate dysmetabolism and that Siah1b, Prkx in Wnt pathway may be candidate genes for NTDs.

Association between MTHFR C677T polymorphism and neural tube defect risks: A comprehensive evaluation in three groups of NTD patients, mothers, and fathers

BACKGROUND

The C677T polymorphism in the methylenetetrahydrofolate reductase gene (MTHFR) gene has been reported to play a critical role in the pathogenesis of neural tube defects (NTDs). The association of the C677T polymorphism in the MTHFR gene and NTD susceptibility has been widely demonstrated, but the results are inconclusive. In this study, we performed a meta-analysis in three groups to investigate the association between the MTHFR C677T polymorphism and NTD risk.

METHODS

A computer retrieval of PubMed, Cochrane Library, CBM, and Embase for papers on the MTHFR C677T polymorphism and NTD risk was performed. All data were analyzed with STATA (Version 13.0). Odds ratios (ORs) with 95% confidence intervals (CIs) were estimated to assess the association. A test for heterogeneity, a sensitivity analysis, and an assessment of publication bias were performed in our meta-analysis.

RESULTS

Forty articles were included in this meta-analysis: 13 studies for Group A: 1329 NTD patients versus 2965 healthy controls; 34 studies for Group B: 3018 mothers with NTD progeny versus 8746 healthy controls; three studies for Group C: 157 fathers with NTD progeny versus 705 healthy controls. The analysis results show: allele contrast in NTD patients: OR = 1.445, 95% CI [1.186, 1.760]; allele contrast in mothers: OR = 1.342, 95% CI [1.166, 1.544]; allele contrast in fathers: OR = 1.062, 95% CI [0.821, 1.374].

CONCLUSION

We found no association between any of the fathers' genotypes and NTDs, whereas a significant correlation between MTHFR C677T polymorphism and NTD risk was found in NTD patients and in their mother.

Challenges in Studying Modifiable Risk Factors for Birth Defects

Conducting research to identify modifiable risk factors for birth defects is difficult for a variety of reasons. While some challenges are familiar to researchers across many disciplines, the confluence of issues affecting birth defects research may not be well understood by those outside of the field. This article describes several methodological challenges to the study of birth defects and ways these challenges might be addressed: (1) ascertainment, definition and classification of birth defects; (2) exposure assessment on modifiable risk factors; (3) analytical challenges related to small numbers and multiple statistical tests; (4) the role of genetics, including the collection of specimens and analysis of genetic data; and (5) challenges in translating research and demonstrating public health impact. Understanding these issues is important for researchers planning studies, reviewers evaluating the scientific merit of results from these studies, and consumers of the research, including fellow researchers, policy makers, health care providers, and families.

Periconceptional folic acid supplementation among pregnant women with epilepsy in a developing country: a retroprospective survey in China

OBJECTIVE

The aims of this study were to investigate the implementation of guidelines on periconceptional folic acid supplementation among pregnant women with epilepsy (WWE) in China and to identify its potential correlations with selected sociodemographic and clinical factors.

METHODS

A detailed investigation was conducted in China using a structured questionnaire from December 2013 to May 2014. Data on the awareness and use of folic acid supplementation, as well as sociodemographic and clinical characteristics, were collected from 153 pregnant WWE. Descriptive analysis, followed by univariate and multivariate logistic regression analyses, was applied to the data from this survey.

RESULTS

Among the enrolled subjects, 67.3% became pregnant after the promulgation of the relevant guidelines. Only 26.2% of them knew the exact effects of folic acid, and 73.8% had taken folic acid at some point during periconception. In addition, the folic acid intake of most of these women (67.1%) did not exceed that of the average pregnant woman. The prevalence of folic acid supplementation for pregnant WWE three months before pregnancy was only 15.5%. There has been almost no improvement in the level of additional awareness and use of folic acid supplementation for WWE since the relevant guidelines were established in China. Pregnant WWE with higher education levels, those with a planned pregnancy, or those who live in urban areas were more likely to know about and implement folic acid supplementation during periconception. Moreover, pregnant WWE with a planned pregnancy or those living in cities seemed to have a higher folic acid intake and started folic acid supplementation earlier before conception.

CONCLUSION

The extent of awareness and use of folic acid supplementation in pregnant WWE remains low in China. More efforts are needed to promote periconceptional folic acid supplementation for WWE, especially those with low education levels and those who live in rural areas. Planned pregnancy should be encouraged for WWE.

The prevalence and nature of the use of preconception services by women with chronic health conditions: an integrative review

Background

There is growing evidence that preconception care may have an important role in preventing short and long term adverse health consequences for women and their offspring. This is particularly the case for women with chronic health conditions due to the rising prevalence of chronic disease in global populations. With this in mind, this paper presents an integrative systematic review of contemporary research outlining the use of preconception services and practices by women with chronic health conditions.

Methods

A search was conducted through PubMed, CINAHL, AMED, and Maternity and Infant Care databases which identified 672 papers examining preconception care and preconception services for women with chronic health conditions. Fourteen papers which were written in English, presented original research, and reported on the prevalence or nature of use of preconception care by women with chronic health conditions were included in the review. Critical appraisal of study quality and thematic categorical grouping of identified papers was undertaken.

Results

Current research evidence, as identified through this review, examines three major topic areas: the prevalence of preconception care practices, use of services and characteristics of users; knowledge of the value and impact of preconception care and availability of preconception services for women with chronic health conditions; and women’s attitudes, approaches and experiences of preconception care and preconception services. Prevalence estimates of engagement with preconception care range between 18.1% and 45%, with most studies focusing on women with type 1 or 2 diabetes. Significant gaps in women’s knowledge of preconception care for women with chronic health conditions were also identified. Women with chronic health conditions reported experiencing emotional distress as a result of their engagement with preconception care services. They also commonly described feeling a need to employ discipline to comply with preconception care programs, and experiencing a fear of pregnancy complications.

Conclusion

Future research requires a broad and sophisticated approach to research design and analysis, improved consideration of temporal changes to women’s health behaviour, representative samples to more effectively inform health policy, and a deeper understanding of women’s motivations, attitudes and perceptions of preconception care to assist in the development of tailored preconception health services.

Prevalence of hyperhomocysteinemia in China: a systematic review and meta-analysis

Hyperhomocysteinemia (HHcy, total homocysteine concentrations > 15 μmol/L) has been associated with increased risk of many diseases. A systematic review was performed to summarize the prevalence of HHcy in China. We searched multiple international and Chinese scientific databases for relevant literature, and further manually screened reference lists and corresponded with original authors. Pooled prevalence of HHcy was calculated using random effects model. Subgroup analysis, meta-regression and sensitivity analysis were also performed. A total of 36 studies consisting 60,754 subjects (57.3% male; age range, 3–97 years) were finally included. The overall pooled prevalence of HHcy was 27.5%. Geographically, the prevalence was high in north areas, intermediate in central areas, and low in south areas, and was higher in inland versus coastal areas. The prevalence increased with age and was significantly higher in men than in women. Rural residents had a slightly higher HHcy prevalence than urban residents, and the studies conducted during 2006 to 2012 presented a higher HHcy prevalence than those during 1990 to 2005. In summary, the prevalence of HHcy in China is high, particularly in northern populations, the inlanders, males, and the elderly. Homocysteine-lowering strategies are necessary to reduce this highly preventable disorder.

RFC-1 80G>A polymorphism in case-mother/control-mother dyads is associated with risk of nephroblastoma and neuroblastoma

AIM

Embryonic tumors are associated with an interruption during normal organ development; they may be related to disturbances in the folate pathway involved in DNA synthesis, methylation, and repair. Prenatal supplementation with folic acid is associated with a decreased risk of neuroblastoma, brain tumors, retinoblastoma, and nephroblastoma. The aim of this study was to investigate the association between MTHFR rs1801133 (C677T) and RFC-1 rs1051266 (G80A) genotypes with the risk of developing nephroblastoma and neuroblastoma.

MATERIALS AND METHODS

Case-mother/control-mother dyad study. Samples from Brazilian children with nephroblastoma (n=80), neuroblastoma (n=66), healthy controls (n=453), and their mothers (case n=93; control n=75) were analyzed. Genomic DNA was isolated from peripheral blood cells and/or buccal cells and genotyped to identify MTHFR C677T and RFC-1 G80A polymorphisms. Differences in genotype distribution between patients and controls were tested by multiple logistic regression analysis.

RESULTS

Risk for nephroblastoma and neuroblastoma was two- to fourfold increased among children with RFC-1 polymorphisms. An increased four- to eightfold risk for neuroblastoma and nephroblastoma was seen when the child and maternal genotypes were combined.

CONCLUSION

Our results suggest that mother and child RFC-1 G80A genotypes play a role on the risk of neuroblastoma and nephroblastoma since this polymorphism may impair the intracellular levels of folate, through carrying fewer folate molecules to the cell interior, and thus, the intracellular concentration is not enough to maintain regular DNA synthesis and methylation pathways.

dNTP deficiency induced by HU via inhibiting ribonucleotide reductase affects neural tube development

Exposure to environmental toxic chemicals in utero during the neural tube development period can cause developmental disorders. To evaluate the disruption of neural tube development programming, the murine neural tube defects (NTDs) model was induced by interrupting folate metabolism using methotrexate in our previous study. The present study aimed to examine the effects of dNTP deficiency induced by hydroxyurea (HU), a specific ribonucleotide reductase (RNR) inhibitor, during murine neural tube development. Pregnant C57BL/6J mice were intraperitoneally injected with various doses of HU on gestation day (GD) 7.5, and the embryos were checked on GD 11.5. RNR activity and deoxynucleoside triphosphate (dNTP) levels were measured in the optimal dose. Additionally, DNA damage was examined by comet analysis and terminal deoxynucleotidyl transferase mediated dUTP nick end-labeling (TUNEL) assay. Cellular behaviors in NTDs embryos were evaluated with phosphorylation of histone H3 (PH-3) and caspase-3 using immunohistochemistry and western blot analysis. The results showed that NTDs were observed mostly with HU treatment at an optimal dose of 225 mg/kg b/w. RNR activity was inhibited and dNTP levels were decreased in HU-treated embryos with NTDs. Additionally, increased DNA damage, decreased proliferation, and increased caspase-3 were significant in NTDs embryos compared to the controls. Results indicated that HU induced murine NTDs model by disturbing dNTP metabolism and further led to the abnormal cell balance between proliferation and apoptosis.

MTHFD1 polymorphism as maternal risk for neural tube defects: a meta-analysis

Recently, the association between methylenetetrahydrofolate dehydrogenase 1 (MTHFD1) G1958A polymorphism and neural tube defects (NTD) susceptibility has been widely investigated; however, the results remained inconclusive. Hence, we conducted a meta-analysis to evaluate the effect of MTHFD1 G1958A polymorphism on NTD. The relative literatures were identified by search of the electronic databases PubMed, MEDLINE, and EMBASE. The extracted data were statistically analyzed, and pooled odds ratios (ORs) with 95 % confidence intervals (CIs) were calculated to estimate the association strength using Stata version 11.0 software. Finally, ten studies met our inclusion criteria, including 2,132/4,082 in NTD infants and controls; 1,402/3,136 in mothers with NTD offspring and controls; and 993/2,879 in fathers with NTD offspring and controls. This meta-analysis showed that, compared with the mothers with GG genotype, the women with AA genotype had an increased risk of NTD in their offspring, with OR values and 95 % CI at 1.39 (1.16-1.68), p < 0.001. Interestingly, fathers with AG genotype had a significant decreased risk of NTD offspring (OR = 0.79, 95 % CI = 0.66-0.94, p = 0.009). However, there was no significant association between the MTHFD1 G1958A polymorphism in NTD patients and the risk of NTD. In conclusion, the present meta-analysis provided evidence of the association between maternal MTHFD1 G1958A polymorphism and NTD susceptibility.

Secular trends in age at menarche among women born between 1955 and 1985 in Southeastern China

Background

Improvements in socioeconomic conditions and population health have been linked to declining age at menarche. In China, secular trends in age at menarche following extensive economic reform during recent decades have not been thoroughly investigated. This study examined the overall trend in age at menarche and assessed differences in the rate of change of age at menarche over time, and between urban and rural populations and education levels in southeastern China.

Methods

Age at menarche was retrospectively collected from 1,167,119 Han Chinese women born 1955–1985, who registered in the Perinatal Health Care Surveillance System in 19 cities and counties in two southeast provinces during 1993–2005. Multivariable linear regression was used to estimate trends in age at menarche overall and stratified by urban/rural residence and education level.

Results

Age at menarche declined by 0.33 [95% CI 0.33, 0.32] years/decade overall, with the fastest decline in women born in 1966–1975. For the earliest birth cohorts (1955–1965), age at menarche declined faster in urban versus rural regions, and for women with high school education or above versus primary school or less. In contrast, age at menarche declined slower among urban women born 1976–1985, and among those with higher education born 1966–1985.

Conclusions

Mean age at menarche declined for women born in 1955–1985 in southeast China. Further study is warranted to identify specific factors contributing to earlier age at menarche and associated health outcomes.

Electronic supplementary material

The online version of this article (doi:10.1186/s12905-014-0155-0) contains supplementary material, which is available to authorized users.

Contemporary issues surrounding folic Acid fortification initiatives

The impact of folate on health and disease, particularly pregnancy complications and congenital malformations, has been extensively studied. Mandatory folic acid fortification therefore has been implemented in multiple countries, resulting in a reduction in the occurrence of neural tube defects. However, emerging evidence suggests increased folate intake may also be associated with unexpected adverse effects. This literature review focuses on contemporary issues of concern, and possible underlying mechanisms as well as giving consideration the future direction of mandatory folic acid fortification. Folate fortification has been associated with the presence of unmetabolized folic acid (PteGlu) in blood, masking of vitamin B12 deficiency, increased dosage for anti-cancer medication, photo-catalysis of PteGlu leading to potential genotoxicity, and a role in the pathoaetiology of colorectal cancer. Increased folate intake has also been associated with twin birth and insulin resistance in offspring, and altered epigenetic mechanisms of inheritance. Although limited data exists to elucidate potential mechanisms underlying these issues, elevated blood folate level due to the excess use of PteGlu without consideration of an individual's specific phenotypic traits (e.g. genetic background and undiagnosed disease) may be relevant. Additionally, the accumulation of unmetabolized PteGlu may lead to inhibition of dihydrofolate reductase and other enzymes. Concerns notwithstanding, folic acid fortification has achieved enormous advances in public health. It therefore seems prudent to target and carefully monitor high risk groups, and to conduct well focused further research to better understand and to minimize any risk of mandatory folic acid fortification.

Preconception serum 1,1,1-trichloro-2,2,bis(p-chlorophenyl)ethane and B-vitamin status: independent and joint effects on women's reproductive outcomes

BACKGROUND

Although preconception 1,1,1-trichloro-2,2,bis(p-chlorophenyl)ethane (DDT) exposure and B-vitamin deficiencies have each been shown to negatively affect human reproductive outcomes, little is known about their joint effect.

OBJECTIVE

We sought to examine whether B-vitamin sufficiency protects against adverse effects of DDT on clinical pregnancy (CP) and subclinical early pregnancy loss (EPL).

DESIGN

We measured preconception concentrations of plasma B vitamins (vitamin B-6, vitamin B-12, and folate) and serum total DDT [sum of p,p' and o,p' isomers of DDT and 1,1-dichloro-2,2-bis(p-chlorophenyl)ethylene] in 291 nulligravid women from Anhui, China, who were studied in 1996-1998. The women were followed prospectively from the time they stopped contraception until CP (gestational age ≥42 d) or 12 mo (whichever occurred first). EPL was identified by using daily urinary human chorionic gonadotropin. The women were categorized according to B-vitamin status (deficiency compared with sufficiency) and DDT concentration (high compared with low).

RESULTS

Of 291 study women, a total of 385 conceptions (31% of which ended in EPL) and 265 CPs occurred. Compared with women with adequate B-vitamins and low DDT, incidence rates of CP were reduced in women with B-vitamin deficiency and a high DDT concentration (P < 0.05 for all). Most notably, in women with sufficient vitamin B-12, DDT was not associated with the incidence of CP; in contrast, in women with vitamin B-12 deficiency, high DDT was associated with a lower incidence of CP (HR: 0.44; 95% CI: 0.23, 0.84); and the test for interaction was significant (P < 0.05). The odds of EPL decreased by 45% (95% CI: 21%, 62%) for each interquartile distance increase in folate in women with high DDT concentrations, and the test for interaction was significant (P = 0.006).

CONCLUSIONS

Our results provide suggestive evidence that vitamin B-12 and folate sufficiency may help protect against adverse reproductive effects of DDT exposure. Additional studies are needed to confirm our findings.

The status of vitamin B12 and folate among Chinese women: a population-based cross-sectional study in northwest China

Objective

To assess the status of the vitamin B12 and folate of Chinese women living in northwest China.

Methods

A population-based cross-sectional study was conducted in 2008 among Chinese women aged 10–49 years living in Shaanxi province of northwest China. A stratified multistage random sampling method was adopted to obtain a sample of 1170 women. The women were interviewed for collection of their background information and their plasma vitamin B12 and folate were measured with the immunoassay method. The status of both vitamins was evaluated and the prevalence of deficiency was estimated.

Results

The median value of the women was 214.5 pg/mL for vitamin B12 and 4.6 ng/mL for folate. The urban women had a significantly higher vitamin B12 (254.1 vs. 195.9 pg/mL) but lower folate (4.4 vs. 4.7 ng/mL) than rural women. Total prevalence of deficiency was 45.5% (95% CI: 42.6%∼48.4%) for vitamin B12 and 14.7% (95% CI: 12.6%∼16.8%) for folate. About 36% of women presented vitamin B12 deficiency alone, 5.2% belonged to folate deficiency alone and 9.5% was combined deficiency in both vitamins. More than 25% of the women were in marginal vitamin B12 status (200–299 pg/mL) and 60% in marginal status of folate (3–6 ng/mL). About 75.2% of rural women with folate deficiency were deficient in vitamin B12 and 46% for urban women. Quantile regression model found decreasing coefficient of folate status across 73 different quantiles of vitamin B12, which indicated that the women with folate deficiency had lower vitamin B12 significantly compared with those with no deficiency.

Conclusions

The deficiency of vitamin B12 and folate is still prevalent among the Chinese women in northwest China. Vitamin B12 deficiency could be more serious and the improvement of poor vitamin B12 status should be invoked when practicing the supplementation of folate against the neural tube defects in northwest China.

The Relationship between Folic Acid and Risk of Autism Spectrum Disorders

There is considerable scientific evidence that many aspects of diet influence the occurrence of human disease. Many factors such as genetic, psychological, environmental and behavioral characteristics influence development of human disease, and there is a close relationship between nutrition and disease. Though typical Western diets are not overtly deficient in essential nutrients, nutriture of a few micro nutrients such as folic acid has been reported to be sub-optimal, particularly in women of childbearing age. The role of folic acid in the prevention of macrocytic anemia and neural tube defects is well established. However, the relationship between folic acid and risk of autism is still evolving. Furthermore, environmental as well as nutritional factors such as folic acid are now well acknowledged as interacting with the individual genetic background in development of several diseases. In this article, recent research regarding the relationship between folic acid and risk of autism is evaluated.

Elevated levels of protein in urine in adulthood after exposure to the Chinese famine of 1959-61 during gestation and the early postnatal period

BACKGROUND

Animal models have suggested that undernutrition during gestation and the early postnatal period may adversely affect kidney development and compromise renal function. As a natural experiment, famines provide an opportunity to test such potential effects in humans. We assessed whether exposure to the Chinese famine of 1959-1961 during gestation and early postnatal life was associated with the levels of proteinuria among female adults three decades after exposure to the famine.

METHODS

We measured famine intensity using the cohort size shrinkage index and we constructed a difference-in-difference model to compare the levels of proteinuria, measured with a dipstick test of random urine specimens, among Chinese women (n = 70 543) whose exposure status to the famine varied across birth cohorts (born before, during or after the famine) and counties of residence with different degrees of famine intensity.

RESULTS

Famine exposure was associated with a greater risk [odds ratio (OR) = 1.54; 95% confidence interval (CI): 1.04, 2.28; P = 0.029) of having higher level of proteinuria among women born during the famine years (1959-61) compared with the unexposed post famine-born cohort (1964-65) in rural samples. No association was observed among urban samples. Results were robust to adjustment for covariates.

CONCLUSIONS

Severe undernutrition during gestation and the early postnatal period may have long-term effects on levels of proteinuria in humans, but the effect sizes may be small.

Replication and exploratory analysis of 24 candidate risk polymorphisms for neural tube defects

Background

Neural tube defects (NTDs), which are among the most common congenital malformations, are influenced by environmental and genetic factors. Low maternal folate is the strongest known contributing factor, making variants in genes in the folate metabolic pathway attractive candidates for NTD risk. Multiple studies have identified nominally significant allelic associations with NTDs. We tested whether associations detected in a large Irish cohort could be replicated in an independent population.

Methods

Replication tests of 24 nominally significant NTD associations were performed in racially/ethnically matched populations. Family-based tests of fifteen nominally significant single nucleotide polymorphisms (SNPs) were repeated in a cohort of NTD trios (530 cases and their parents) from the United Kingdom, and case–control tests of nine nominally significant SNPs were repeated in a cohort (190 cases, 941 controls) from New York State (NYS). Secondary hypotheses involved evaluating the latter set of nine SNPs for NTD association using alternate case–control models and NTD groupings in white, African American and Hispanic cohorts from NYS.

Results

Of the 24 SNPs tested for replication, ADA rs452159 and MTR rs10925260 were significantly associated with isolated NTDs. Of the secondary tests performed, ARID1A rs11247593 was associated with NTDs in whites, and ALDH1A2 rs7169289 was associated with isolated NTDs in African Americans.

Conclusions

We report a number of associations between SNP genotypes and neural tube defects. These associations were nominally significant before correction for multiple hypothesis testing. These corrections are highly conservative for association studies of untested hypotheses, and may be too conservative for replication studies. We therefore believe the true effect of these four nominally significant SNPs on NTD risk will be more definitively determined by further study in other populations, and eventual meta-analysis.

Electronic supplementary material

The online version of this article (doi:10.1186/s12881-014-0102-9) contains supplementary material, which is available to authorized users.

Preconception care: nutritional risks and interventions

INTRODUCTION

There is increasingly a double burden of under-nutrition and obesity in women of reproductive age. Preconception underweight or overweight, short stature and micronutrient deficiencies all contribute to excess maternal and fetal complications during pregnancy.

METHODS

A systematic review and meta-analysis of the evidence was conducted to ascertain the possible impact of preconception care for adolescents, women and couples of reproductive age on maternal, newborn and child health (MNCH) outcomes. A comprehensive strategy was used to search electronic reference libraries, and both observational and clinical controlled trials were included. Cross-referencing and a separate search strategy for each preconception risk and intervention ensured wider study capture.

RESULTS

Maternal pre-pregnancy weight is a significant factor in the preconception period with underweight contributing to a 32% higher risk of preterm birth, and obesity more than doubling the risk for preeclampsia, gestational diabetes. Overweight women are more likely to undergo a Cesarean delivery, and their newborns have higher chances of being born with a neural tube or congenital heart defect. Among nutrition-specific interventions, preconception folic acid supplementation has the strongest evidence of effect, preventing 69% of recurrent neural tube defects. Multiple micronutrient supplementation shows promise to reduce the rates of congenital anomalies and risk of preeclampsia. Although over 40% of women worldwide are anemic in the preconception period, only one study has shown a risk for low birth weight.

CONCLUSION

All women, but especially those who become pregnant in adolescence or have closely-spaced pregnancies (inter-pregnancy interval less than six months), require nutritional assessment and appropriate intervention in the preconception period with an emphasis on optimizing maternal body mass index and micronutrient reserves. Increasing coverage of nutrition-specific and nutrition-sensitive strategies (such as food fortification; integration of nutrition initiatives with other maternal and child health interventions; and community based platforms) is necessary among adolescent girls and women of reproductive age. The effectiveness of interventions will need to be simultaneously monitored, and form the basis for the development of improved delivery strategies and new nutritional interventions.

Raltitrexed's effect on the development of neural tube defects in mice is associated with DNA damage, apoptosis, and proliferation

The causal metabolic pathway and the underlying mechanism between folate deficiency and neural tube defects (NTDs) remain obscure. Thymidylate (dTMP) is catalyzed by thymidylate synthase (TS) using the folate-derived one-carbon unit as the sole methyl donor. This study aims to examine the role of dTMP biosynthesis in the development of neural tube in mice by inhibition of TS via a specific inhibitor, raltitrexed (RTX). Pregnant mice were intraperitoneally injected with various doses of RTX on gestational day 7.5, and embryos were examined for the presence of NTDs on gestational day 11.5. TS activity and changes of dUMP and dTMP levels were measured following RTX treatment at the optimal dose. DNA damage was determined by detection of phosphorylated replication protein A2 (RPA2) and γ-H2AX in embryos with NTDs induced by RTX. Besides, apoptosis and proliferation were also analyzed in RTX-treated embryos with NTDs. We found that NTDs were highly occurred by the treatment of RTX at the optimal dose of 11.5 mg/kg b/w. RTX treatment significantly inhibited TS activity. Meanwhile, dTMP was decreased associated with the accumulation of dUMP in RTX-treated embryos. Phosphorylated RPA2 and γ-H2AX were significantly increased in RTX-treated embryos with NTDs compared to control. More apoptosis and decreased proliferation were also found in embryos with NTDs induced by RTX. These results indicate that impairment of dTMP biosynthesis caused by RTX led to the development of NTDs in mice. DNA damage and imbalance between apoptosis and proliferation may be potential mechanisms.

Geographical and ethnic distribution of single nucleotide polymorphisms within genes of the folate/homocysteine pathway metabolism

High levels of plasma homocysteine are associated with an increased risk of many health conditions influenced by both environmental and genetic factors. The objective of this study was to provide the geographical distribution of folate pathway genetic polymorphisms in Mexico and the comparison with the reported frequencies in different continental populations. This study included the analysis of the genotypic frequencies of eight polymorphisms in genes of the folate/homocysteine metabolic pathway in 1,350 Mestizo and Amerindian subjects from different regions in Mexico and 836 individuals from European, African and Asian populations of the 1,000 Genomes Project. In Mexican Mestizo and Amerindian populations, the MTHFR C677T risk genotype (TT) was highly prevalent (frequency: 25 and 57 %, respectively). In Mestizos, the frequency showed clear regional variation related to ancestry; the Guerrero subpopulation with the highest Amerindian contribution had the highest TT frequency (33 %). The MTHFD1 G1958A AA risk genotype was also enriched in Mexican Mestizos and Amerindians (frequency: 34 and 58 %, respectively), whereas in African and Asian ancestry populations the frequency for AA was low (~4 %). All together risk genotypes showed regional differences, and Sonora had significantly different genetic frequencies compared with the other regions (P value <0.05). Our study illustrates differential geographical distribution of the risk variants in the folate/homocysteine metabolic pathway relative to ethnic background. This work supports that certain areas of the world have increased needs for folic acid and vitamin B supplementation, and this information needs to be considered in public health guidelines and eventually policies.

Bigger babies born to women survivors of the 1959-1961 Chinese famine: a puzzle due to survival selection?

The Chinese Famine of 1959-1961 caused up to 30 million deaths. It varied in intensity across China and affected rural areas disproportionately. Data from the China-U.S. Collaborative Project for Neural Tube Defect Prevention on 31, 449 women (born 1957-1963) and their offspring birth size were recorded in 1993-1996. We used a measure of famine intensity at county level based on the size of famine-born cohorts relative to cohorts preceding and following the famine in a difference-in-difference model that compared offspring birth size of pre-famine (1957-1958; exposed between 0.5 and 4.5 years), famine (1959-1961; prenatal and up to 2.5 years) and post-famine (1962; some exposed in early pregnancy) cohort groups to that of the unexposed 1963 cohort. The model corrected for age and cohort trends and estimated associations between maternal famine exposure and offspring birth size for the average level of famine intensity across counties, and included adjustment for clustering. In rural areas and in pre-famine and famine cohorts, exposure to famine was associated with larger weight (69 g; 95% CI 30, 108), length (0.3 cm; 95% CI -0.0, 0.5) and birth body mass index (0.1 kg/m2; 95% CI 0.0, 0.2). In urban areas, however, exposure to famine was not associated with offspring birth size. Our findings in rural areas suggest that severe and prolonged famine leads to larger newborn size in the offspring of mothers exposed to famine in utero and during the first few years of life; less severe famine in urban areas however, appeared to have no impact. The markedly increased mortality in rural areas may have resulted in the selection of hardier mothers with greater growth potential, which becomes expressed in their offspring.

A critical role of noggin in developing folate-nonresponsive NTD in Fkbp8 -/- embryos

PURPOSE

Maternal folate intake has reduced the incidence of human neural tube defects by 60-70 %. However, 30-40 % of cases remain nonresponsive to folate intake. The main purpose of this study was to understand the molecular mechanism of folate nonresponsiveness in a mouse model of neural tube defect.

METHODS

We used a folate-nonresponsive Fkbp8 knockout mouse model to elucidate the molecular mechanism(s) of folate nonresponsiveness. Neurospheres were grown from neural stem cells isolated from the lumbar neural tube of E9.5 Fkbp8 (-/-) and wild-type embryos. Immunostaining was used to determine the protein levels of oligodendrocyte transcription factor 2 (Olig2), Nkx6.1, class III beta-tubulin (TuJ1), O4, glial fibrillary acidic protein (GFAP), histone H3 Lys27 trimethylation (H3K27me3), ubiquitously transcribed tetratricopeptide repeat (UTX), and Msx2, and quantitative real-time (RT)-PCR was used to determine the message levels of Olig2, Nkx6.1, Msx2, and noggin in neural stem cells differentiated in the presence and absence of folic acid.

RESULTS

Fkbp8 (-/-)-derived neural stem cells showed (i) increased noggin expression; (ii) decreased Msx2 expression; (iii) premature differentiation--neurogenesis, oligodendrogenesis (Olig2 expression), and gliogenesis (GFAP expression); and (iv) increased UTX expression and decreased H3K27me3 polycomb modification. Exogenous folic acid did not reverse these markers.

CONCLUSIONS

Folate nonresponsiveness could be attributed in part to increased noggin expression in Fkbp8 (-/-) embryos, resulting in decreased Msx2 expression. Folate treatment further increases Olig2 and noggin expression, thereby exacerbating ventralization.

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.

Risk of congenital malformations among offspring of mothers and fathers with celiac disease: a nationwide cohort study

BACKGROUND & AIMS

Many patients with celiac disease experience malabsorption, weight loss, and anemia; undiagnosed celiac disease during pregnancy has been linked with adverse outcomes. Studies of celiac disease and congenital malformations in offspring have been underpowered. We investigated the risk of congenital malformations among the offspring of parents with celiac disease.

METHODS

We performed a nationwide cohort study of data from linked health care registers in Sweden from 1973 through 2009. We collected histopathology data from 28 pathology departments in Sweden to identify individuals with celiac disease (based on the presence of villous atrophy). We estimated the risks of malformations in the offspring of mothers and fathers with and without celiac disease. Logistic regression was used to estimate adjusted prevalence odds ratios (aPORs) with 95% confidence intervals (CIs).

RESULTS

Among 11,382 offspring of mothers with celiac disease, there were 672 cases (5.9%) of malformation compared with 2098 cases (5.1%) among 40,922 offspring of mothers without celiac disease. Similarly, 352 (5.9%) of 6002 offspring of fathers with celiac disease and 1009 (5.1%) of 19,600 offspring of fathers without celiac disease had a malformation. In adjusted analyses, the offspring of mothers or fathers with celiac disease had a slightly increased risk of having children with malformations (for those with mothers with celiac disease: aPOR, 1.15; 95% CI, 1.05-1.26; for those with fathers with celiac disease: aPOR, 1.14; 95% CI, 1.00-1.29). However, these excess risks decreased or vanished entirely when we restricted our data to births since 2000 (for those with mothers with celiac disease: aPOR, 1.11; and 95% CI, 0.79-1.56; for those with fathers with celiac disease: aPOR, 1.01; 95% CI, 0.81-1.26).

CONCLUSIONS

In a nationwide study, we found an increased risk for malformation among the offspring of mothers or fathers with celiac disease. However, the excess risk is small; the upper limits of the CIs for malformation indicate a 29% maximum relative increase.