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

A national estimate of the birth prevalence of congenital anomalies in India: systematic review and meta-analysis

Background

A quarter of all global neonatal deaths occur in India. Congenital anomalies constitute the fifth largest cause of neonatal mortality in the country, but national estimates of the prevalence of these conditions are lacking. The objective of the study was to derive an estimate of the birth prevalence of congenital anomalies in India.

Methods

The search was carried out in PubMed and pooled prevalence was estimated using the inverse variance method. A random effects model was used due to high heterogeneity between the studies. Forest plots were generated using the Review Manager software.

Results

The PubMed search identified 878 articles from which 52 hospital based and three community based studies were included in the meta-analysis. The pooled prevalence of congenital anomaly affected births was 184.48 per 10,000 births (95% CI 164.74–204.21) among 802,658 births. Anomalies of the musculoskeletal system were highest among live births while the prevalence of central nervous system defects was highest when stillbirths were included in the analysis. Anencephaly and talipes were the most commonly reported anomalies.

Conclusions

Data from this meta-analysis suggests that there may be as many as 472,177 (421,652 to 522,676) congenital anomaly affected births in India each year. Population based studies using standard definitions are needed to validate these estimates. The two most frequently reported anomalies were anencephaly that is potentially preventable through preconception folate supplementation, and talipes which can be corrected using relatively low cost interventions. Studies are needed to determine the impact of congenital anomalies on neonatal mortality in India.

Simultaneous quantitation of folates, flavins and B6 metabolites in human plasma by LC-MS/MS assay: Applications in colorectal cancer

An analytical method using electrospray ionization and high- performance liquid chromatography/tandem mass spectrometry (LC/ESI-MS/MS) was developed to quantify the vitamin B metabolites found in the folate one-carbon metabolism, using 50 μL of human plasma. Analytes in plasma were extracted using protein precipitation after being stabilized in 1% ascorbic acid. The analytes were separated using a Kinetex 2.6 μm Pentafluorophenyl (2.1 × 30 mm) column utilizing a gradient mobile phase system of 0.1% formic acid in water and 100% acetonitrile in a 13.2 min run. The MS detector run using a positive multiple reaction monitoring with parameters optimized for each analyte's ion pair. The assay was selective and linear for all analytes at defined dynamic ranges. The recoveries were generally above 80% except for the folate metabolites whose recoveries dipped possibly due to the drying process. The inter-day precision (%coefficient of variation) and accuracy (%calculated concentration of the nominal concentrations) for six replicates of all quality control samples were ≤14% and within 12.2%, respectively. The lower limit of quantification ranged from 0.2 to 3.9 nM. No significant instability was observed after repeated freezing and thawing or in processed samples. The LC-MS/MS assay was found applicable for sensitive, accurate and precise quantitation of vitamin B metabolites in plasma of healthy volunteers and colorectal cancer patients.

Formate rescues neural tube defects caused by mutations in Slc25a32

Periconceptional folic acid (FA) supplementation significantly reduces the prevalence of neural tube defects (NTDs). Unfortunately, some NTDs are FA resistant, and as such, NTDs remain a global public health concern. Previous studies have identified SLC25A32 as a mitochondrial folate transporter (MFT), which is capable of transferring tetrahydrofolate (THF) from cellular cytoplasm to the mitochondria in vitro. Herein, we show that gene trap inactivation of Slc25a32 (Mft) in mice induces NTDs that are folate (5-methyltetrahydrofolate, 5-mTHF) resistant yet are preventable by formate supplementation. Slc25a32gt/gt embryos die in utero with 100% penetrant cranial NTDs. 5-mTHF supplementation failed to promote normal neural tube closure (NTC) in mutant embryos, while formate supplementation enabled the majority (78%) of knockout embryos to complete NTC. A parallel genetic study in human subjects with NTDs identified biallelic loss of function SLC25A32 variants in a cranial NTD case. These data demonstrate that the loss of functional Slc25a32 results in cranial NTDs in mice and has also been observed in a human NTD patient.

The Chinese Children and Families Cohort Study: The Nutrition, Physical Activity, and Ultraviolet Radiation Data Collection

This article reports the study design, methodological issues and early results of a pilot study testing methods for collecting nutrition, physical activity, and ultraviolet (UV) radiation exposure data in a groundbreaking study in China. Epidemiological studies suggest that exposures across the entire life course, including in utero, early childhood, and adolescence, may be important in the etiology of adult cancers and other chronic diseases. The Chinese Children and Families Cohort Study intends to follow-up subjects from the 1993 to 1995 Community Intervention Program of folic acid supplementation for the prevention of neural tube defects. This cohort is unique in that only folic acid exposure during pregnancy varies between groups as other supplements were not available, and there were nutrient deficiencies in the populations. Prior to launching a large-scale follow-up effort, a pilot study was conducted to assess the feasibility of recontacting original study participants to collect extensive diet, physical activity, and UV radiation exposure data in this population. The pilot study included 92 mothers and 184 adolescent children aged 14 to 17 years from 1 urban and 1 rural Community Intervention Program site. Subjects completed a Food Frequency Questionnaire, a 3-day food record, a physical activity questionnaire, a 3-day sun exposure diary together with 3 days of personal UV dosimetry, and 7 days of pedometry measurements and provided blood, saliva, and toenail samples. Grip strength and body composition measurements were taken, and ambient solar UV radiation was monitored in both study sites. While most of the assessments were successful, future studies would likely require different dietary intake instruments. The purpose of this report is to describe the study design and methodological issues emerging from this pilot work relevant for the follow-up of this large birth cohort.

Folate Nutrition Status in Mothers of the Boston Birth Cohort, Sample of a US Urban Low-Income Population

OBJECTIVES

To examine maternal folic acid supplementation and plasma folate concentrations in the Boston Birth Cohort, a predominantly urban, low-income, minority population in Boston, Massachusetts.

METHODS

This report includes 7612 mothers with singleton live births (3829 Black, 2023 Hispanic, 865 White, and 895 others) enrolled in the Boston Birth Cohort at the Boston Medical Center, during 1999 to 2014. Folic acid supplementation during preconception and each trimester was obtained via interview questionnaire. In a subset (n = 2598), maternal plasma folate concentrations were measured in blood samples drawn within a few days of delivery.

RESULTS

The percentage of mothers taking folic acid supplementation almost daily during preconception and the first, second, and third trimesters were 4.3%, 55.9%, 59.4%, and 58.0%, respectively. Most striking, we observed a wide range of maternal plasma folate concentrations, with approximately 11% insufficient (< 13.4 nmol/L) and 23% elevated (> 45.3 nmol/L).

CONCLUSIONS

Findings indicate that fewer than 5% of mothers in the Boston Birth Cohort started folic acid supplements before pregnancy, and approximately one third of mothers had either too low or too high plasma folate levels, which may have important health consequences on both the mother and the child.

Evidence for potential underestimation of clinical folate deficiency in resource-limited countries using blood tests

Although a low serum folate concentration is a useful biomarker of pure folate deficiency, the presence of vitamin B12 deficiency or hemolysis or both in individuals with low folate status predictably raises serum folate levels. Therefore, in resource-limited settings where dietary folate deficiency can coexist with vitamin B12 deficiency or malaria or both, the serum folate concentration can range from normal to high, leading to serious underestimation of tissue folate status. This review traces the genesis of an inappropriate overreliance on the serum folate concentration to rule out folate deficiency in vulnerable populations of women and children. Of significance, without due consideration of a chronically inadequate dietary folate intake, authors of influential studies have likely wrongly judged these populations to have an adequate folate status. Through repetition, this error has led to a dangerous entry into the contemporary medical literature that folate deficiency is rare in women and children. As a consequence, many millions of under-resourced women and children with mild to moderate tissue folate deficiency may have been deprived of folate replacement. This review uses historical documents to challenge earlier conclusions and re-emphasizes the need for contextual integration of clinical information in resource-limited settings.

Race and ethnicity and preconception folic acid supplement use among pregnant women in Georgia, PRAMS 2009 to 2011

BACKGROUND

The United States Public Health Service recommends that all women of reproductive age consume 400 μg of folic acid daily to prevent major neural tube defects. Hispanics have the highest prevalence of neural tube defects compared with other race/ethnic groups. We studied prevalence of preconception folic acid supplement use, and its association with race/ethnicity among pregnant women in Georgia.

METHODS

Using state-wide population-based data from 2009 to 2011 Georgia Pregnancy Risk Assessment Monitoring System, we examined the prevalence of preconception folic acid supplement use among pregnant women aged 18 to 45 years. We conducted multivariable logistic regression and estimated adjusted odds ratios and 95% confidence intervals to examine the association between race/ethnicity and supplemental folic acid use among study participants.

RESULTS

Overall, 25% of all participants reported taking folic acid supplements daily before conception. Only 21% of Hispanic women reported preconception folic acid supplement use. Hispanic women were twice as likely to not take folic acid supplements (adjusted odds ratio = 2.15; 95% confidence interval, 1.35-3.40) compared with non-Hispanic whites, after controlling for maternal age, parity, pregnancy intention, knowledge that folic acid prevents birth defects, and preconception smoking and exercise.

CONCLUSION

Hispanics are a growing population in the United States with an expected 14 million women of child-bearing age by 2020, and the prevalence of preconception folic acid supplement use is low in this group with a high risk of neural tube defects. Promotion of voluntarily fortified corn masa flour can lower neural tube defects in Hispanics. Mandatory corn masa fortification will be a more effective public health policy.Birth Defects Research 109:38-48, 2017. © 2016 Wiley Periodicals, Inc.

The pharmacokinetic advantage of 5-methyltetrahydrofolate for minimization of the risk for birth defects

Despite efforts to increase folic acid (FA) intake, even within countries mandating FA fortification, there remain pregnant women with folate levels inadequate to minimize congenital disorders (e.g., of the neural tube, heart, and lip/palate). The pharmacokinetics of FA and [6S]-5-methyltetrahydrofolate (5-MTHF) were examined to find a reliable and minimal dose for rapidly rescuing folate status prior to critical periods of embryonic development. Serum total folate increased much more rapidly over the first four days in insufficient women given 7.5 mg doses of 5-MTHF than the same regimen of FA (P for trend <0.0001). Nearly all women given 7.5 mg 5-MTHF (every 12 hours, five doses total) almost immediately reached 50 nM serum total folate. Moreover, this level could be maintained by subsequent administration of 0.4 mg/d of folic acid. Thus, 5-MTHF enables repletion of folate stores more quickly and uniformly than FA and without exposure to unmetabolized FA.

The Evolving Role of Multivitamin/Multimineral Supplement Use among Adults in the Age of Personalized Nutrition

Micronutrient deficiencies occur in segments of the adult population in the United States. Multivitamin/multimineral supplements (MVMS) are widely used by this population, which reduces inadequacies in micronutrient intake, but the potential for exceeding tolerable upper intake levels in others should be considered. There are concerns associated with the excessive intake of certain nutrients, particularly folic acid, and potential untoward consequences. The advent of nutrigenomics and the enhanced ability to directly study the interactions between nutrition and genetic variants and expression will allow for the conduct of more targeted studies with specific endpoints and may ultimately lead to progress in the field of personalized nutrition. The role of MVMS in health maintenance and chronic disease prevention remains controversial. Conducting studies in this area has been hampered by, among other factors, inconsistent definitions of MVMS, ranging from as few as three vitamins to broad-spectrum products containing more than two dozen vitamins and minerals. Results from some observational studies and large-scale, randomized, controlled trials suggest that MVMS may reduce the risk of some forms of cancer and, potentially, cardiovascular disease. The ongoing COcoa Supplement and Multivitamin Outcomes Study (COSMOS) is expected to build on this research and provide additional insights into these areas.

Oxidative Stress and Apoptosis in Benzo[a]pyrene-Induced Neural Tube Defects

Neural tube defects (NTDs) are among the most common and severe congenital malformations and result from incomplete closure of the neural tube during early development. Maternal exposure to polycyclic aromatic hydrocarbons (PAHs) has been suggested to be a risk factor for NTDs and previous studies imply that the mechanism underlying the association between PAH exposure and NTDs may involve oxidative stress and apoptosis. The objectives of this study were to investigate whether there is a direct effect of maternal benzo[α] pyrene (BaP) exposure on the closure of the neural tube in mice, and to examine the underlying mechanisms by combining animal experiments and human subject studies. We found that intraperitoneal injection of BaP from embryonic day 7 at a dose of 250 mg kg^-1 induced NTDs (13.3% frequency) in ICR mice. BaP exposure significantly increased expression of genes associated with oxidative stress, Cyp1a1, Sod1 and Sod2, while repressing Gpx1. Elevated apoptosis and higher protein expression of cleaved caspase-3 in the neuroepithelium of treated embryos were observed. Pre-treatment with vitamin E, added to food, significantly protected against BaP-induced NTDs (1.4% frequency) (P < 0.05). Vitamin E also partly normalized oxidative stress related gene expression and excess apoptosis in BaP-treated embryos. Examination of human neural tissues revealed that increased levels of protein carbonyl and apoptosis were related with maternal exposure to PAHs and the risk of NTDs. Collectively, these results suggest that BaP exposure could induce NTDs and that this may involve increased oxidative stress and apoptosis, while vitamin E may have a protective effect.

A public health approach for preventing neural tube defects: folic acid fortification and beyond

In this paper we review the evidence basis for prevention of folic acid-sensitive neural tube defects (NTDs) through public health interventions in women of reproductive age (WRA), the proven vehicles for delivery of folic acid, and what is needed to effectively scale these, and provide a snapshot of potential innovations that require future research. Our primary focus is on the global situation affecting large-scale food fortification (LSFF) with folic acid, in particular the fortification of wheat flour and maize meal. Our overarching conclusion is that folic acid fortification is an evidence-based intervention that reduces the prevalence of NTDs, and that LSFF with folic acid is underutilized. Thus, food fortification with folic acid should be a component of most national public health strategies, in particular where folate status is insufficient and a fortifiable food vehicle, processed by a centralized industry, is consumed regularly by WRA. The evidence shows that there is still much work needed (1) to build the enabling environment and expand programs where there is currently no legislation, (2) to improve the low quality of delivery of existing programs, and (3) to measure and sustain programs by generating new coverage data and demonstrating evidence of impact in low- and middle-income countries.

Proteins as Nano-Carriers for Bioactive Compounds. The Case of 7S and 11S Soy Globulins and Folic Acid Complexation

Isolated 7S and 11S globulins obtained from defeated soy flour were complexated with folic acid (FA) in order to generate nano-carriers for this important vitamin in human nutrition. Fluorescence spectroscopy and dynamic light scattering were applied to follow the nano-complexes formation and for their characterization. Fluorescence experimental data were modeled by the Stern-Volmer and a modified double logarithm approach. The results obtained confirmed static quenching. The number of binding sites on the protein molecule was ~1. The values obtained for the binding constants suggest a high affinity between proteins and FA. Particle size distribution allowed to study the protein aggregation phenomenon induced by FA bound to the native proteins. Z-average manifested a clear trend to protein aggregation. 11S-FA nano-complexes resulted in more polydispersity. ζ-potential of FA nano-complexes did not show a remarkable change after FA complexation. The biological activity of nano-complexes loaded with FA was explored in terms of their capacity to enhance the biomass formation of Lactobacillus casei BL23. The results concerning to nano-complexes inclusion in culture media showed higher bacterial growth. Such a result was attributed to the entry of the acid by the specific receptors concomitantly by the peptide receptors. These findings have technological impact for the use of globulins-FA based nano-complexes in nutraceutical, pharmaceutical and food industries.

Folate status in women of reproductive age as basis of neural tube defect risk assessment

Reliable folate status data for women of reproductive age (WRA) to assess global risk for neural tube defects (NTDs) are needed. We focus on a recent recommendation by the World Health Organization that a specific "optimal" red blood cell (RBC) folate concentration be used as the sole indicator of NTD risk within a population and discuss how to best apply this guidance to reach the goal of assessing NTD risk globally. We also emphasize the importance of using the microbiologic assay (MBA) as the most reliable assay for obtaining comparable results for RBC folate concentration across time and countries, the need for harmonization of the MBA through use of consistent key reagents and procedures within laboratories, and the requirement to apply assay-matched cutoffs for folate deficiency and insufficiency. To estimate NTD risk globally, the ideal scenario would be to have country-specific population-based surveys of RBC folate in WRA determined utilizing a harmonized MBA, as was done in recent studies in Guatemala and Belize. We conclude with guidance on next steps to best navigate the road map toward the goal of generating reliable folate status data on which to assess NTD risk in WRA in low- and middle-income countries.

Genetic screening and functional analysis of CASP9 mutations in a Chinese cohort with neural tube defects

AIM

Neural tube defects (NTDs) are birth defects of the nervous system and are the second most frequent cause of birth defects worldwide. The etiology of NTDs is complicated and involves both genetic and environmental factors. CASP9 is an initiator caspase in the intrinsic apoptosis pathway, which in Casp9^-/- mice has been shown to result in NTDs because of decreased apoptosis. The aim of this study was to evaluate the potential genetic contribution of the CASP9 gene in human NTDs.

METHODS

High-throughput sequencing was performed to screen genetic variants of CASP9 genes in 355 NTD cases and 225 matched controls. Apoptosis-relevant assays were performed on transiently transfected E9 neuroepithelial cells or human embryonic kidney 293T cells, to determine the functional characteristics of NTD-specific rare variants under complete or low folic acid (FA) status.

RESULTS

We found significant expression of CASP9 rare variants in NTDs and identified 4 NTD-specific missense variants. Functional assays demonstrated that a p.Y251C variant attenuates apoptosis by reducing CASP9 protein expression and decreasing activity of the intrinsic apoptosis pathway. From this, we conclude that this variant may represent a loss-of-function mutation. A 4-time recurrent p.R191G variant did not affect intrinsic apoptosis in complete medium, while it completely inhibited apoptosis induced by low FA medium.

CONCLUSION

Our findings identify a genetic link for apoptosis in human NTDs and highlight the effect of gene-environment interactions in a complex disease.

Inhibition of thymidylate synthase affects neural tube development in mice

Thymidylate synthase (TYMS) is a key enzyme in the de novo synthesis of 2'-deoxythymidine-5'-monophosphate (dTMP) from 2'-deoxyuridine-5'-monophosphate (dUMP). Our aim was to investigate the role of dTMP dysmetabolism via inhibition of TYMS by an inhibitor, 5-fluorouracil (5-FU) in the occurrence of neural tube defects (NTDs). We found that a high incidence of NTDs occurred after treatment with 5-FU at 12.5 mg/kg body weight. TYMS activity was significantly inhibited with decreased dTMP and accumulation of dUMP after 5-FU injection. The proliferation of neuroepithelial cells were markedly inhibited in NTDs compared with control. Expressions of proliferating cell nuclear antigen and phosphohistone H3 were significantly decreased in NTDs, while phosphorylated replication protein A2, P53 and Caspase3 were significantly increased in NTDs compared with control. These results indicated that inhibition of TYMS affected the balance between proliferation and apoptosis in neuroepithelial cells, which might shed some lights on the mechanisms involved in NTDs.

Total prevention of folic acid-preventable spina bifida and anencephaly would reduce child mortality in India: Implications in achieving Target 3.2 of the Sustainable Development Goals

BACKGROUND

The potential to reduce child mortality by preventing folic acid-preventable spina bifida and anencephaly (FAP SBA) is inadequately appreciated. To quantify possible reduction in FAP SBA-associated child mortality in low- and middle-income countries, we conducted an analysis to demonstrate in India, a country with more than 25 million births and 1.2 million under-five deaths each year, the decrease in neonatal, infant, and under-five mortality that would occur through total prevention of FAP SBA.

METHODS

We estimated the percent reductions in neonatal, infant, and under-five mortality that would have occurred in India in 2015 had all of FAP SBA been prevented. We also estimated the contributions of these reductions toward India's Sustainable Development Goals on child mortality indicators. We considered the overall prevalence of spina bifida and anencephaly in India as 5 per 1,000 live births, of which 90% were preventable with effective folic acid intervention.

RESULTS

In the year 2015, folic acid interventions would have prevented about 116,070 cases of FAP SBA and 101,565 under-five deaths associated with FAP SBA. Prevention of FAP SBA would have reduced annually, neonatal, infant, and under-five mortality by 10.2%, 8.9%, and 8.3%, respectively. These reductions would have contributed 18.5% and 17.2% to the reductions in neonatal and under-five mortality, respectively, needed by India to achieve its 2030 Sustainable Developmental Goal Target 3.2 addressing preventable child mortality.

CONCLUSIONS

Total prevention of FAP SBA clearly has a significant potential for immediate reductions in neonatal, infant, and under-five mortality in India, and similarly other countries.

Prenatal folic acid use associated with decreased risk of myelomeningocele: A case-control study offers further support for folic acid fortification in Bangladesh

Neural tube defects contribute to severe morbidity and mortality in children and adults; however, they are largely preventable through maternal intake of folic acid before and during early pregnancy. We examined the association between maternal prenatal folic acid supplement intake and risk of myelomeningocele (a severe and common type of neural tube defect) in the offspring. We performed secondary analysis using data from a case-control study conducted at Dhaka Community Hospital, Bangladesh between April and November of 2013. Cases and controls included children with and without myelomeningocele, respectively, and their mothers. Cases were identified from local hospitals and rural health clinics served by Dhaka Community Hospital. Controls were selected from pregnancy registries located in the same region as the cases, and matched (1:1) to cases by age and sex.

Myelomeningocele in the offspring was confirmed by a pediatrician with expertise in classifying neural tube defects. Maternal prenatal folic acid supplement intake was the main exposure of interest. We estimated crude and adjusted odds ratios (OR) and 95% confidence intervals (CI) using conditional logistic regression analysis. There were 53 pairs of matched cases and controls in our study. Overall, 51% of case mothers reported using folic acid supplements during pregnancy compared to 72% of control mothers (p = 0.03). Median plasma folate concentrations at the time of study visit were 2.79 ng/mL and 2.86 ng/mL among case and control mothers, respectively (p = 0.85). Maternal prenatal folic acid use significantly decreased the odds of myelomeningocele in the offspring (unadjusted OR = 0.42, 95% CI = 0.18–0.96). The association was slightly attenuated after adjusting for maternal age at the time of pregnancy (adjusted OR = 0.43, 95% CI = 0.18–1.02). Our study confirms the protective association between maternal prenatal folic acid supplement use and myelomeningocele among children born in Bangladesh. Our findings point to an overall low folic acid supplement use and low plasma folate concentrations among women of reproductive age in Bangladesh. Mandatory fortification of staple foods with folic acid can address low folate status among women of child-bearing age, and prevent child morbidity and mortality associated with myelomeningocele in Bangladesh.

A 2015 global update on folic acid-preventable spina bifida and anencephaly

BACKGROUND

Spina bifida and anencephaly are two major neural tube defects. They contribute substantially to perinatal, neonatal, infant, and under-five mortality and life-long disability. To monitor the progress toward the total prevention of folic acid-preventable spina bifida and anencephaly (FAP SBA), we examined their global status in 2015.

METHODS

Based on existing data, we modeled the proportion of FAP SBA that are prevented in the year 2015 through mandatory folic acid fortification globally. We included only those countries with mandatory fortification that added at least 1.0 ppm folic acid as a fortificant to wheat and maize flour, and had complete information on coverage. Our model assumed mandatory folic acid fortification at 200 μg/day is fully protective against FAP SBA, and reduces the rate of spina bifida and anencephaly to a minimum of 0.5 per 1000 births.

RESULTS

Our estimates show that, in 2015, 13.2% (35,500 of approximately 268,700 global cases) of FAP SBA were prevented in 58 countries through mandatory folic acid fortification of wheat and maize flour. Most countries in Europe, Africa, and Asia were not implementing mandatory fortification with folic acid.

CONCLUSION

Knowledge that folic acid prevents spina bifida and anencephaly has existed for 25 years, yet only a small fraction of FAP SBA is being prevented worldwide. Several countries still have 5- to 20-fold epidemics of FAP SBA. Implementation of mandatory fortification with folic acid offers governments a proven and rapid way to prevent FAP SBA-associated disability and mortality, and to help achieve health-related Sustainable Development Goals. Birth Defects Research (Part A) 106:520-529, 2016. © 2016 Wiley Periodicals, Inc.

Folate, vitamin B12, homocysteine and polymorphisms in folate metabolizing genes in children with congenital heart disease and their mothers

BACKGROUND/OBJECTIVES

The objective of the study was to assess the role of variations in serum folate, vitamin B12, homocysteine and the presence of genetic polymorphisms as risk factors for congenital heart disease (CHD) in children.

SUBJECTS/METHODS

A total of 32 children with CHD, and their mothers and 32 normal children and their mothers formed the study and control groups, respectively. Serum folate, vitamin B12 and homocysteine as well as genetic polymorphisms MTHFR C677→︀T, MTHFR A1298→︀C, MTR A2756→︀G and MTRR A66→︀G were assessed.

RESULTS

Low serum folate and genetic polymorphisms MTHFR C677→︀T and MTRR A66→︀G among children and their mothers and high homocysteine among mothers were noted as risk factors for CHD (P<0.05). Vitamin B12 levels were normal and showed no association. Presence of MTHFR C677→︀T and MTRR A66→︀G, both concurrently among children as well as mothers and simultaneously among mother-child pairs, showed several fold increase in the risk for CHD. On multivariate analysis, the risk factors noted for CHD were presence of MTHFR C677→︀T among children and their mothers and MTRR A66→︀G among mothers. Analyses for nutrient-gene interaction revealed significant associations between low serum folate and high serum homocysteine levels, and the presence of selected genetic polymorphisms.

CONCLUSIONS

Low serum folate, high homocysteine and presence of selected genetic polymorphisms among children and their mothers were noted as risk factors for CHD. Nutrient-gene interaction being a modifiable risk factor, the study recommends the use of peri-conceptional folate supplementation with vitamin B12 sufficiency for primary prevention of CHD.

Genetic polymorphisms and folate status

Moderate hyperhomocysteinemia-induced low folate status is an independent risk factor for cardiovascular disease, dementia, and depression. Folate is an essential cofactor in the one-carbon metabolism pathway and is necessary in amino acid metabolism, purine and thymidylate synthesis, and DNA methylation. In the folate cycle and homocysteine metabolism, folate, vitamin B12, vitamin B6, and vitamin B2 are important cofactors. Many enzymes are involved in folate transport and uptake, the folate pathway, and homocysteine (Hcy) metabolism, and various polymorphisms have been documented in these enzymes. Serum folate and total Hcy (tHcy) levels are influenced by folate intake and genetic polymorphisms in 5,10-methylenetertahydrofolate reductase (MTHFR) such as C677T. The prevalence of the MTHFR 677TT genotype varies across ethnic groups and regions, with a frequency of approximately 15% in Japanese populations. Individuals with the TT genotype have significantly higher tHcy levels and lower folate levels in serum than those with the CT and TT genotypes. However, administration of folic acid has been shown to eliminate these differences. Moreover, data have suggested that interventions based on genotype may be effective for motivating individuals to change their lifestyle and improve their nutrition status. Accordingly, in this review, we discuss the effects of MTHFR C677T polymorphisms on serum tHcy and folate levels with folic acid intervention and evaluate approaches for overcoming folic acid deficiency and related symptoms.

Neural tube defects: Risk factors and preventive measures

For the last 25 years, it has been proven that the occurrence or recurrence of neural tube defects can be prevented with the administration of folic acid before and early pregnancy. At present, over 80 countries in the world, except Japan, have mandated the fortification of wheat flour and/or rice with folic acid, which has resulted in a significant reduction in the prevalence of neural tube defects. In 2000, the Japanese government recommended folic acid 400 μg daily for young women of childbearing age and women who are planning to conceive. In 2002, the government started to present information about the importance of folic acid in the development of fetuses in the Mother-Child Health Booklet annually. Despite these endeavors, the prevalence of neural tube defects has remained unchanged. We discuss the risk factors of neural tube defects and propose preventive measures to decrease the number of neonates with neural tube defects. We believe that the government should implement the fortification of staple food with folic acid very soon, which will eventually decrease not only the neonatal mortality and morbidity, but also the economic burden on our health care system.

Maternal Prenatal Folic Acid Supplementation Programs Offspring Lipid Metabolism by Aberrant DNA Methylation in Hepatic ATGL and Adipose LPL in Rats

The effects of maternal prenatal folic acid supplementation (FAS) on offspring lipid metabolism in adulthood remains unclear, although prenatal FAS is compulsively suggested in many countries. Female Sprague-Dawley rats were fed with control (CON) or FAS diets before and during pregnancy. Male offspring of CON and FAS dams were further divided into two groups at seven weeks for CON and high-fat (HF) diet interventions for eight weeks in adulthood (n = 10). The interactive effects of maternal prenatal FAS and offspring HF in adulthood on lipid metabolism and DNA methylation of genes involved in lipids metabolism were assessed. The male offspring of FAS dams had elevated serum and liver triglyceride level when fed with HF compared to the male offspring of CON dams. The mRNA and protein expression levels of hepatic ATGL and adipose LPL were significantly decreased in offspring of FAS dams than in offspring of CON dams. Furthermore, maternal prenatal FAS resulted in elevated DNA methylation levels in the promoter and first exon region of hepatic ATGL and adipose LPL in offspring. Maternal FAS exacerbated the adverse effects of HF on lipid metabolism in offspring through inducing aberrant DNA methylation levels of hepatic ATGL and adipose LPL.

Mediterranean diet, folic acid, and neural tube defects

The Mediterranean diet has been for a very long time the basis of food habits all over the countries of the Mediterranean basin, originally founded on rural models and low consumption of meat products and high-fat/high-processed foods. However, in the modern era, the traditional Mediterranean diet pattern is now progressively eroding due to the widespread dissemination of the Western-type economy, life-style, technology-driven culture, as well as the globalisation of food production, availability and consumption, with consequent homogenisation of food culture and behaviours. This transition process may affect many situations, including pregnancy and offspring's health. The problem of the diet during pregnancy and the proper intake of nutrients are nowadays a very current topic, arousing much debate. The Mediterranean dietary pattern, in particular, has been associated with the highest risk reduction of major congenital anomalies, like the heterogeneous class of neural tube defects (NTDs). NTDs constitute a major health burden (0.5-2/1000 pregnancies worldwide) and still remain a preventable cause of still birth, neonatal and infant death, or significant lifelong disabilities. Many studies support the finding that appropriate folate levels during pregnancy may confer protection against these diseases. In 1991 one randomised controlled trial (RCT) demonstrated for the first time that periconceptional supplementation of folic acid is able to prevent the recurrence of NTDs, finding confirmed by many other subsequent studies. Anyway, the high rate of unplanned/unintended pregnancies and births and other issues hindering the achievement of adequate folate levels in women in childbearing age, induced the US government and many other countries to institute mandatory food fortification with folic acid. The actual strategy adopted by European Countries (including Italy) suggests that women take 0,4 mg folic acid/die before conception. The main question is which intervention, between folic acid supplementation, foods fortification or both, linked to a healthy life-style and diet pattern may represent the best method in preventing NTDs. The aim of this review is to describe the actual situation in NTDs prevention, with a special attention to the Italiancontext concerning this delicate and controversial subject.

A missense mutation in TCN2 is associated with decreased risk for congenital heart defects and may increase cellular uptake of vitamin B12 via Megalin

Deregulation of folate and vitamin B12 (VB12) metabolism contributes to the risk of congenital heart defects (CHDs). Transcobalamin (TCN2) is essential for transporting VB12 from blood to cells as TCN2-bound VB12 (holo-TC) is the only form for somatic cellular uptake. In this study, we performed an association study between common polymorphisms in 46 one carbon metabolism genes and CHD in 412 CHDs and 213 controls. Only two significant association signals in coding regions were identified: FTCD c.1470C>T & TCN2 c.230A>T. The only missense mutation, TCN2 c.230A>T, was further validated in 412 CHDs and 1177 controls. TCN2 c.230T is significantly associated with reduced CHD risk in North Chinese (odds ratio = 0.67, P = 4.62e-05), compared with the 230A allele. Interestingly, the mean level of plasma holo-TC in women with the TA genotype was 1.77-fold higher than that in women with the AA genotype. Further analysis suggested that c.230A>T enhanced the cellular uptake of holo-TC via the LRP2 receptor. Our results determined that a functional polymorphism in TCN2 contributes to the prevalence of CHDs. TCN2 c.230A>T is significantly associated with a reduced CHD risk, likely due to TCN2 c.230T improving the interaction between holo-TC and its LRP2 receptor.

Large -scale wheat flour folic acid fortification program increases plasma folate levels among women of reproductive age in urban Tanzania

There is widespread vitamin and mineral deficiency problem in Tanzania with known deficiencies of at least vitamin A, iron, folate and zinc, resulting in lasting negative consequences especially on maternal health, cognitive development and thus the nation's economic potential. Folate deficiency is associated with significant adverse health effects among women of reproductive age, including a higher risk of neural tube defects. Several countries, including Tanzania, have implemented mandatory fortification of wheat and maize flour but evidence on the effectiveness of these programs in developing countries remains limited. We evaluated the effectiveness of Tanzania's food fortification program by examining folate levels for women of reproductive age, 18-49 years. A prospective cohort study with 600 non-pregnant women enrolled concurrent with the initiation of food fortification and followed up for 1 year thereafter. Blood samples, dietary intake and fortified foods consumption data were collected at baseline, and at 6 and 12 months. Plasma folate levels were determined using a competitive assay with folate binding protein. Using univariate and multivariate linear regression, we compared the change in plasma folate levels at six and twelve months of the program from baseline. We also assessed the relative risk of folate deficiency during follow-up using log-binomial regression. The mean (±SE) pre-fortification plasma folate level for the women was 5.44-ng/ml (±2.30) at baseline. These levels improved significantly at six months [difference: 4.57ng/ml (±2.89)] and 12 months [difference: 4.27ng/ml (±4.18)]. Based on plasma folate cut-off level of 4 ng/ml, the prevalence of folate deficiency was 26.9% at baseline, and 5% at twelve months. One ng/ml increase in plasma folate from baseline was associated with a 25% decreased risk of folate deficiency at 12 months [(RR = 0.75; 95% CI = 0.67-0.85, P<0.001]. In a setting where folate deficiency is high, food fortification program with folic acid resulted in significant improvements in folate status among women of reproductive age.

Folate deficiency facilitates recruitment of upstream binding factor to hot spots of DNA double-strand breaks of rRNA genes and promotes its transcription

The biogenesis of ribosomes in vivo is an essential process for cellular functions. Transcription of ribosomal RNA (rRNA) genes is the rate-limiting step in ribosome biogenesis controlled by environmental conditions. Here, we investigated the role of folate antagonist on changes of DNA double-strand breaks (DSBs) landscape in mouse embryonic stem cells. A significant DSB enhancement was detected in the genome of these cells and a large majority of these DSBs were found in rRNA genes. Furthermore, spontaneous DSBs in cells under folate deficiency conditions were located exclusively within the rRNA gene units, representing a H3K4me1 hallmark. Enrichment H3K4me1 at the hot spots of DSB regions enhanced the recruitment of upstream binding factor (UBF) to rRNA genes, resulting in the increment of rRNA genes transcription. Supplement of folate resulted in a restored UBF binding across DNA breakage sites of rRNA genes, and normal rRNA gene transcription. In samples from neural tube defects (NTDs) with low folate level, up-regulation of rRNA gene transcription was observed, along with aberrant UBF level. Our results present a new view by which alterations in folate levels affects DNA breakage through epigenetic control leading to the regulation of rRNA gene transcription during the early stage of development.

The recurrence risk of neural tube defects (NTDs) in a population with high prevalence of NTDs in northern China

Background

Although a number of studies have reported the recurrence risk of NTDs in developed countries, there is little data on the rate of recurrence of NTDs in northern China, a region of high prevalence of NTDs.

Methods

Based on the population-based birth defects surveillance system of five counties, we identified women who had an NTD affected pregnancy from 2004-2015 and a retrospective survey was conducted. The rate of recurrence of NTDs was calculated by the number of recurrent NTDs divided by the first NTDs. Maternal age, body mass index (BMI), gestational weeks, education, and occupation were collected. Information on folic acid (FA) supplements, time and dosage were also recorded.

Results

Among 851 women who had a previous NTD-affected pregnancy, there were 578 subsequent pregnancies, with 10 recurrent NTDs, a 1.7% recurrence rate. The recurrence rate was 1.5% and 2.6% for those taking FA supplements and without FA supplementation respectively. Women with recurrent NTDs had higher BMI before pregnancy compared to those who had a second pregnancy without NTDs. Among the recurrent NTDs, the majority were spina bifida.

Conclusions

The recurrence rate of NTDs was approximately five times higher than the overall prevalence in the same region of northern China. Risk of recurrence appeared lower among women who took FA supplements. These findings are consistent with the reduction in NTD frequency in the population since introduction of the nationwide FA supplement program. Data on recurrence rates in northern China will inform power calculations for future intervention studies.

Impact of Periconceptional Folic Acid Supplementation on Low Birth Weight and Small-for-Gestational-Age Infants in China: A Large Prospective Cohort Study

OBJECTIVES

To explore the effects of maternal folic acid supplementation alone during pregnancy on the incidence of low birth weight (LBW) and small-for-gestational-age (SGA) infant status.

STUDY DESIGN

Data were derived from a large population-based cohort study performed in China to evaluate the prevention of neural tube defects with folic acid supplementation. The sample comprised 200 589 singleton live births registered in 2 southern Chinese provinces by mothers for whom detailed information on folic acid use was available. Gestational age was calculated from the first day of the last menstrual period. LBW was defined as a birth weight <2500 g. Infants were considered SGA when the age-adjusted birth weight was below the 10th percentile as defined by a national survey performed in 1998. Logistic regression was used to estimate the effects of folic acid after adjusting for the principal potential confounders.

RESULTS

The overall incidence of LBW and SGA status was 2.18% and 5.82%, respectively. The incidence of LBW and SGA status was 2.09% and 5.73% in women who took folic acid, and 2.27% and 5.90% in those who did not. The adjusted risk ratios associated with folic acid use were 0.85 (95% CI: 0.80-0.90) for LBW and 0.93 (95% CI: 0.89-0.96) for SGA status. Folic acid use during pregnancy appeared to be particularly important to prevent LBW and SGA status.

CONCLUSIONS

A maternal daily intake of 400 µg folic acid alone significantly reduced the risks of infant LBW and SGA status.

Using latent class cluster analysis to screen high risk clusters of birth defects between 2009 and 2013 in Northwest China

In the study, we aimed to explore the synergistic effects of multiple risk factors on birth defects, and examine temporal trend of the synergistic effects over time. Two cross-sectional surveys conducted in 2009 and 2013 were merged and then latent class cluster analysis and generalized linear Poisson model were used. A total of 9085 and 29094 young children born within the last three years and their mothers were enrolled in 2009 and 2013 respectively. Three latent maternal exposure clusters were determined: a high-risk, a moderate-risk, and a low-risk cluster (88.97%, 1.49%, 9.54% in 2009 and 82.42%, 3.39%, 14.19% in 2013). The synthetic effects of maternal exposure to multiple risk factors could increase the risk of overall birth defects and cardiovascular system malformation among live births, and this risk is significantly higher in high-risk cluster than that in low-risk cluster. After adjusting for confounding factors using a generalized linear Poisson model, in high-risk cluster the prevalence of nervous system malformation decreased by approximately 2.71%, and the proportion of cardiovascular system malformation rose by 0.92% from 2009 to 2013. The Chinese government should make great efforts to provide primary prevention for those on high-risk cluster as a priority target population.

Prevalence of Neural Tube Defects and the Impact of Prenatal Diagnosis in Three Districts of Beijing, China

BACKGROUND

The objectives of this study were to explore the prevalence of neural tube defects (NTDs) in three districts of Beijing, and to evaluate the impact of prenatal diagnosis on the prevalence.

METHODS

Data were collected between 2006 and 2012 from the Beijing Birth Defects Surveillance System. P₁₃ and P₂₈ represent the prevalence of NTDs diagnosed from 13 weeks and 28 weeks of gestation, respectively, to 7 days after delivery. Populations were classified as household (permanent) and non-household (non-permanent) because differences exist in access to health care, education, and income, among others.

RESULTS

The P₁₃ of NTDs was 11.7 per 10 000 births in the three districts, which declined from 2006-12. In addition, the prevalence of NTDs in the non-household population was 1.7-fold higher than that among the household population. The P₁₃ of anencephaly, spina bifida, and encephalocele were 5.3, 4.9, 1.6, respectively, per 10 000 births. The P₂₈ of NTDs only represented 29.1% of P₁₃ , and this proportion decreased over the 7-year period.

CONCLUSIONS

The prevalence of NTDs remains high in the three districts of Beijing, and the rate was higher in the non-household than household population. The prevalence of birth defects would be under estimated by almost 70 per cent if the report time was set on 28 weeks' gestation or later compared with report time on 13 weeks of gestation. It is better to set the report time earlier in birth defect surveillance in contemporary China.

Genetic Risk Factors for Folate-Responsive Neural Tube Defects

Neural tube defects (NTDs) are the most severe congenital malformations of the central nervous system. The etiology is complex, with both genetic and environmental factors having important contributions. Researchers have known for the past two decades that maternal periconceptional use of the B vitamin folic acid can prevent many NTDs. Though this finding is arguably one of the most important recent discoveries in birth defect research, the mechanism by which folic acid exerts this benefit remains unknown. Research to date has focused on the hypothesis that an underlying genetic susceptibility interacts with folate-sensitive metabolic processes at the time of neural tube closure. Little progress has been made searching for risk-causative variants in candidate genes; therefore, more complex genetic and epigenetic methodologies are now being considered. This article reviews the research to date that has been targeted on this important gene-nutrient locus.

Clinical and molecular genetic characterization of two siblings with trisomy 2p24.3-pter and monosomy 5p14.3-pter

Partial trisomy 2p syndrome is occasionally associated with neural tube defects (NTDs), such as anencephaly, encephalocele, and spina bifida, in addition to common features of intellectual disability, developmental delay, and characteristic facial appearance. The 2p24 region has been reported to be associated with NTDs. Here, we report the cases of 2 siblings with trisomy 2p24.3-pter and monosomy 5p14.3-pter caused by the paternal translocation t(2;5)(p24.3;p14.3). Of the two siblings, the elder sister had spina bifida. We determined the nucleotide sequences of the chromosomal breakpoints and found that the sizes of trisomy 2p and monosomy 5p segments were 18.77 and 17.89 Mb, respectively. NTDs were present in four of seven previously reported patients with trisomy 2p and monosomy 5p as well as in one of the two patients examined in the present study. Although the monosomy 5p of the nine patients were similar in size, the two patients reported here had the smallest size of trisomy 2p. When the clinical features of the nine patients were compared to the present two patients, the elder sister had postaxial polydactyly of the left foot in addition to the characteristic facial appearance and spina bifida, indicating that these features were associated with trisomy 2p24.3-pter. To our knowledge, this is the first study on spina bifida to determine the nucleotide sequences of breakpoints for trisomy 2p24.3-pter and monosomy 5p14.3-pter. Increased gene dosages of dosage-sensitive genes or genes at the trisomy segment (2p24.3) of the presented patients could be associated with NTDs of patients with trisomy 2p.

Scorecard for spina bifida research, prevention, and policy - A development process

Spina bifida is a serious and largely preventable neural tube birth defect and an important cause of mortality and lifelong disability. The People and Organizations United for Spina Bifida and Hydrocephalus (PUSH!) Global Alliance was formed in 2014 to provide a common platform for various organizations worldwide to raise the visibility of spina bifida and hydrocephalus. In its formative phase, the alliance recognized that in order to accelerate surveillance, prevention, and care for these conditions, there was a need to provide an evidence-based assessment of how nations are performing in specific areas. In this paper, we describe the impetus for, and the process of, developing country-level scorecards for spina bifida surveillance, prevention and care. The PUSH! Executive Committee formulated a comprehensive list of six actionable indicators measuring availability of published studies on population-based folate studies; surveillance of prevalence and mortality; prevention-based policies; access to care; and quality of life associated with spina bifida. Rubrics were developed to score each country on the aforementioned indicators. Country scores were pooled across each indicator and the composite scores ranged between zero and three if there was a need for improvement, four and five if they were in good standing, or six for an excellent status. The scorecard included country-specific recommendations assimilated from the literature and published guidelines to aid policy makers in accelerating surveillance and prevention, and improving the care and quality of life indicators. For comparison, country-level scorecards were grouped by WHO-regions. Score cards were made available publicly through the website "www.pu-sh.org".

Trends and characteristics of fetal and neonatal mortality due to congenital anomalies, Colombia 1999-2008

OBJECTIVE

To describe fetal and neonatal mortality due to congenital anomalies in Colombia.

METHODS

We analyzed all fetal and neonatal deaths due to a congenital anomaly registered with the Colombian vital statistics system during 1999-2008.

RESULTS

The registry included 213,293 fetal deaths and 7,216,727 live births. Of the live births, 77,738 (1.08%) resulted in neonatal deaths. Congenital anomalies were responsible for 7321 fetal deaths (3.4% of all fetal deaths) and 15,040 neonatal deaths (19.3% of all neonatal deaths). The fetal mortality rate due to congenital anomalies was 9.9 per 10,000 live births and fetal deaths; the neonatal mortality rate due to congenital anomalies was 20.8 per 10,000 live births. Mortality rates due to congenital anomalies remained relatively stable during the study period. The most frequent fatal congenital anomalies were congenital heart defects (32.0%), central nervous system anomalies (15.8%), and chromosomal anomalies (8.0%). Risk factors for fetal and neonatal death included: male or undetermined sex, living in villages or rural areas, mother's age >35 years, low and very low birthweight, and <28 weeks gestation at birth.

CONCLUSIONS

Congenital anomalies are an important cause of fetal and neonatal deaths in Colombia, but many of the anomalies may be preventable or treatable.

Preconception and prenatal genetic counselling

Identifying individuals at risk of having children affected by genetic conditions or congenital anomalies allows counselling that aims to inform reproductive decisions. This process takes place either at the preconception or early prenatal stage, although more options are available if risks are identified before the pregnancy. Preconception counselling covers issues that can affect the health of the mother and baby including folic acid supplementation. Carrier screening for autosomal recessive diseases, such as beta thalassaemia, has resulted in a significantly reduced incidence in many countries. National organisations, however, advocate more in-depth research before such screening recommendations apply to the general population. Recently, advances in genomic technologies have made it possible to greatly expand the scope of genetic screening, with the aim of providing more comprehensive information to prospective parents. This is a complex field, and research should focus on how the technology can be put to best use in the future.

Periconceptional folic acid supplementation and vitamin B12 status in a cohort of Chinese early pregnancy women with the risk of adverse pregnancy outcomes

Maternal folate and vitamin B12 deficiency predict poor pregnancy outcome. To improve pregnancy outcomes in rural area of China, we investigate rural women's folic acid supplementation (FAS) status and the associations between maternal vitamin B status during the first trimester and subsequent adverse pregnancy outcomes. We collected the questionnaire information and drew 5 ml of blood from 309 early pregnant rural women. The birth outcomes were retrieved from medical records after delivery. Out of the total, 257 had taken FAS, including 50 before conception (group A) and 207 during the first trimester (group B). The concentration of plasma folate and the RBC folate supplementation groups were obviously higher than that of no-supplementation group (group N, p<0.01). The mean vitamin B12 levels in FAS group were significantly higher than those in groups N and B (p<0.05). Women who delivered SGA or premature infants had reduced plasma folate levels (p<0.05) compared with controls. The multiple linear regression models revealed that RBC folate levels affected the infant birth weight (p<0.01) and birth length (p<0.05). In conclusion, FAS can significantly improve plasma folate and RBC folate levels in childbearing-age women and reduce the risk of subsequent adverse pregnancy outcomes.

Supplémentation préconceptionnelle en acide folique / multivitamines pour la prévention primaire et secondaire des anomalies du tube neural et d'autres anomalies congénitales sensibles à l'acide folique

OBJECTIF

Offrir des renseignements à jour sur l'utilisation pré et postconceptionnelle d'acide folique par voie orale, avec ou sans supplément de multivitamines / micronutriments, aux fins de la prévention des anomalies du tube neural et d'autres anomalies congénitales. Ces renseignements aideront les médecins, les sages-femmes, les infirmières et les autres professionnels de la santé à contribuer aux efforts de sensibilisation des femmes quant à l'utilisation et aux posologies adéquates de la supplémentation en acide folique / multivitamines, avant et pendant la grossesse. RéSULTATS: La littérature publiée a été récupérée par l'intermédiaire de recherches menées dans PubMed, Medline, CINAHL et la Cochrane Library en janvier 2011 au moyen d'un vocabulaire contrôlé et de mots clés appropriés (p. ex. « folic acid », « prenatal multivitamins », « folate sensitive birth defects », « congenital anomaly risk reduction », « pre-conception counselling »). Les résultats ont été restreints aux analyses systématiques, aux études observationnelles et aux essais comparatifs randomisés / essais cliniques comparatifs publiés en anglais entre 1985 et juin 2014. Les recherches ont été mises à jour de façon régulière et intégrées à la directive clinique jusqu'en juin 2014. La littérature grise (non publiée) a été identifiée par l'intermédiaire de recherches menées dans les sites Web d'organismes s'intéressant à l'évaluation des technologies dans le domaine de la santé et d'organismes connexes, dans des collections de directives cliniques, dans des registres d'essais cliniques, et auprès de sociétés de spécialité médicale nationales et internationales. COûTS, RISQUES ET AVANTAGES: Les coûts financiers sont ceux de la supplémentation quotidienne en vitamines et de la consommation d'un régime alimentaire santé enrichi en folate. Les risques sont ceux qui sont liés à une association signalée entre la supplémentation alimentaire en acide folique et des modifications épigénétiques fœtales / la probabilité accrue d'obtenir une grossesse gémellaire. Ces associations pourraient devoir être prises en considération avant la mise en œuvre d'une supplémentation en acide folique. La supplémentation en acide folique par voie orale (ou l'apport alimentaire en folate combiné à un supplément de multivitamines / micronutriments) a pour avantage de mener à une baisse connexe du taux d'anomalies du tube neural et peut-être même des taux d'autres complications obstétricales et anomalies congénitales particulières.

VALEURS

La qualité des résultats est évaluée au moyen des critères décrits par le Groupe d'étude canadien sur les soins de santé préventifs (Tableau 1). DéCLARATION SOMMAIRE: RECOMMANDATIONS.

Gestational weight gain, cesarean delivery, and cesarean delivery on maternal request: a cohort analysis of Chinese nulliparous women

PURPOSE

To examine the association between gestational weight gain (GWG) and cesarean delivery including cesarean delivery on maternal request (CDMR) among low-risk women.

METHODS

A total of 1,009,987 Chinese nulliparous women who delivered live term singletons during 1993-2010 were included. GWG, according to maternal pre-pregnancy body mass index-specified z-scores, was categorized into five groups: less than -1.2, -1.2 to less than -0.6, -0.6 to 0.6 (reference), more than 0.6 to 1.2, and more than 1.2. Multivariate log-binomial regression models were used to estimate the adjusted risk ratios and 95% confidence intervals (95% CIs).

RESULTS

GWG was positively associated with overall cesarean and CDMR after adjusting for various confounders. Adjusted risk ratios for cesarean were 0.75 (95% CI, 0.73-0.77), 0.84 (95% CI, 0.82-0.85), 1.00, 1.16 (95% CI, 1.14-1.19), and 1.32 (95% CI, 1.29-1.35) in five ascending GWG categories, and 0.70 (95% CI, 0.67-0.73), 0.80 (95% CI, 0.78-0.82), 1.00, 1.20 (95% CI, 1.18-1.23), and 1.43 (95% CI, 1.40-1.45) for CDMR. The graded positive associations were consistent across levels of maternal pre-pregnancy body mass index, and in strata defined by southern and/or northern provinces, urban and/or rural residence, maternal age at delivery, year of delivery, and level of delivering hospital.

CONCLUSIONS

Even among low-risk women, higher GWG was monotonically associated with an increased risk of cesarean delivery, indicating that limiting GWG could benefit to curb the rate of both medically necessary and unnecessary cesareans.