Comparison of blood folate levels among pregnant Chinese women in areas with high and low prevalence of neural tube defects

Folic acid supplements and perinatal mortality in China

Introduction

Periconceptional use of multivitamins containing folic acid prevents external major birth defects, especially neural tube defects. We aimed to explore the effects of maternal folic acid supplementation alone on perinatal mortality with or without external major birth defects plus neural tube defects.

Methods

From the China-US Collaborative Project for Neural Tube Defects Prevention, we identified 222, 303 singleton pregnancies with detailed information on periconceptional folic acid use, defined as folic acid supplementary before the last menstrual date until to the end of the first trimester. Perinatal mortality included stillbirths after 20 weeks' gestation and early neonatal deaths within 7 days of delivery.

Results

Among the fetuses or infants of women who did not take folic acid, the rate of perinatal mortality was 2.99% and 1.62% at least 20 weeks' gestation in the northern and southern regions. Among the fetuses or infants of the women with periconceptional use of folic acid, the rates were 1.85% and 1.39% in the northern and southern region. The estimated relative risk for perinatal mortality [adjusted risk ratio (RR), 0.72; 95% confidence interval (CI), 0.61- 0.85], stillbirth (adjusted RR, 0.78; 95% CI, 0.64-0.96), early neonatal mortality (adjusted RR, 0.61; 95% CI, 0.45-0.82), and neonatal death (adjusted RR, 0.64; 95% CI, 0.49-0.83) in northern China was significantly decreased in association with periconceptional folic acid supplementation. Compared with northern, there was a lesser effect in southern China.

Conclusion

Periconceptional intake of 400μg folic acid daily reduces the overall risk perinatal mortality, as well as the risk from external major birth defects and neural tube defects, especially in northern China.

Is the Tradeoff between Folic Acid or/and Multivitamin Supplementation against Birth Defects in Early Pregnancy Reconsidered? Evidence Based on a Chinese Birth Cohort Study

BACKGROUND

Several studies have reported conflicting results on the association between maternal exposure to folic acid (FA) and/or multivitamin (MV) supplements and the risk of birth defects (BDs), especially for different subtypes of BDs. The present study aimed to identify the association between maternal exposure to FA or/and MV and BDs in offspring.

METHODS

In the Chinese Birth Cohort Study initiated from 20 November 2017, 120,652 pregnant women completed follow-up until 20 August 2021. The participants were classified into four groups: without exposure to FA and MV, exposure to only FA, exposure to only MV, and exposure to FA and MV. Birth defects were coded by the International Classification of Diseases (ICD)-10. In order to explore the structural relationship between maternal FA or MV supplements and BDs, directed acyclic graphs were drawn. Then, an inverse probability treatment weighting was utilized to reduce the systematic differences in the baseline characteristics among the different groups. Lastly, a two-level mixed-effect log binomial regression analysis was used to estimate the relative risk (RR) value of the different subtypes of BDs under different exposures to FA and/or MV.

RESULTS

Compared with the maternal group without exposure to FA and MV, the RR values of nervous system defects, face, ear, and neck defects, limb defects, and CHDs in the maternal group with only FA supplementation were less than 1.0, but they were not statistically significant. The RR values of genitourinary defects, abnormal chromosomes, and oral clefts were more than 1.0, and they were also not statistically significant. However, the risk of genitourinary defects (RR: 3.22, 95% CI: 1.42-7.29) and chromosomal abnormalities (RR: 2.57, 95% CI: 1.16-5.73) in the maternal group with only MV supplementation increased more than those in the maternal group without exposure to FA and MV. In addition, the RR values of all subtypes of BDs in the maternal group with exposure to FA and MV were closer to 1.0 than those in maternal group with exposure to only MV, but they were not statistically significant.

CONCLUSIONS

It was indicated that the simultaneous supplementation of FA and MV in early pregnancy may have an interaction for the prevention of BDs and may have inconsistent effects for different subtypes of BDs. At the same time, excessive FA supplementation in pregnant women may increase the risk of BDs in their offspring. Although the mechanism is not clear, this evidence reminded us that more trade-offs are necessary for formulating strategies for the prevention of BDs with FA and/or MV supplementation in early pregnancy.

Regional distribution of the MTHFR C677T polymorphism in Chinese females

Objective: For analyzing the distribution characteristics of MTHFR C677T polymorphism in Chinese females in order to provide information for reducing birth defects and formulating public health policies to prevent congenital malformations. Methods: Literature search in the last 6 years on "MTHFR C677T," "polymorphism" and "methylene tetrahydrofolate reductase." The included literature provides the MTHFR C677T frequency in healthy females in the corresponding regions. The data were grouped by the national administrative region as a unit to obtain the distribution information of the MTHFR C677T and alleles in the female population in every province, municipality or autonomous region. This was done for analyzing the overall distribution of the MTHFR C677T allele and the geographical distribution of pregnancy complications. Results: A total of 126 studies were included, covering five autonomous areas, four municipalities directly under the Central Government, as well as 22 provinces (except Taiwan Province) in China. MTHFR C677T polymorphism data of 27 groups of Chinese Han women and 31 groups of other Chinese females were obtained, and the chi-square test revealed notable inter-group differences (p = 0.000). The TT genotype and T allele of MTHFR C677T accounted for 18.2% (4.7%-38.3%) and 40.3% (19.7%-61.4%) of the Chinese female population, respectively, with a significant north-south difference. Chinese females had a consistent frequency of the T allele with the geographical distribution of pregnancy complications such as recurrent abortion and preeclampsia. Conclusion: With a obvious geographical gradient, the MTHFR C677T polymorphism distribution in Chinese females is consistent with the geographical distribution of multiple pregnancy complications, and the risk assessment for it might be included in primary prevention for birth defects.

Folic acid supplementation and risk for congenital hydrocephalus in China

OBJECTIVE

We examined whether folic acid (FA) supplementation prevented congenital hydrocephalus (CH) in more than 200 000 births in China.

DESIGN

A large population-based cohort study.

SETTING

All births at 20 complete gestational weeks, including live births, stillbirths and pregnancy terminations, and all structural birth defects regardless of gestational week were recorded. The prevalence of births with CH was classified by maternal characteristics and FA supplementation. CH was diagnosed in accordance with code 742.3 of the International Classification of Diseases, Ninth Revision, Clinical Modification, while non-neural tube defect (NTD) CH refers to CH without anencephaly (740), spina bifida (741) or encephalocele (742·0).

PARTICIPANTS

A total of 247 831 pregnant women who delivered with known outcomes were included.

RESULTS

A total of 206 cases of CH (0·83 per 1000 births) and 170 cases of non-NTD CH (0·69 per 1000 births) were recorded in the study. The prevalence of CH and non-NTD CH was higher in women in the no supplementation group than those in the FA supplementation group (0·92 and 0·72 v. 0·75 and 0·65 per 1000 births, respectively). FA supplementation during the periconceptional period significantly prevented CH (OR = 0·29, 95 % CI 0·12, 0·69) and non-NTD CH (OR = 0·34, 95 % CI 0·12, 0·97) in northern China, especially in a high-compliance group (≥ 80 %).

CONCLUSIONS

Periconceptional FA supplementation did not significantly prevent CH overall in the current study. However, in the north of China with common maternal folate insufficiency, there was some evidence.

Folic acid supplementation and risk for fetal abdominal wall defects in China: results from a large population-based intervention cohort study

Folic acid (FA) can reduce the risk for selected birth defects other than neural tube defects. We examined whether FA has preventive effects against fetal abdominal wall defects (AWD) in a unique intervention cohort in China. Birth outcomes of 247 831 singleton births from a population-based cohort study with detailed pre-conceptional FA intake information were collected in China in 1993-1996. Information on births at 20 complete gestational weeks, including live births, stillbirths and pregnancy terminations, and all structural birth defects regardless of gestational week were recorded. The birth prevalence of omphalocele, gastroschisis and total fetal AWD was classified by maternal FA supplementation. The prevalence of total AWD was 4·30 per 10 000 births among women who took FA compared with 13·46 per 10 000 births among those who did not take FA in northern China and 6·28 and 5·18 per 10 000 births, respectively, in southern China. The prevalence of omphalocele was 0·54 per 10 000 births among women who took FA compared with 3·74 per 10 000 births among those who did not take FA in northern China and 1·79 and 1·44 per 10 000 births, respectively, in southern China. FA supplementation significantly prevented total AWD in multivariate analysis (relative risk 0·26, 95 % CI 0·11, 0·61) in northern China, although no preventive effect of FA on AWD was observed in southern China. FA supplementation successfully reduced the prevalence of AWD in northern China.

Association Between MTHFR C677T Polymorphism and Susceptibility to Autism Spectrum Disorders: A Meta-Analysis in Chinese Han Population

Prior studies have examined the influence of MTHFR C677T on autism susceptibility, however, there are no consensus conclusions and specific analyses of a Chinese population. This meta-analysis included a false-positive report probability (FPRP) test to comprehensively evaluate the association of MTHFR C677T polymorphism with autism susceptibility among a Chinese Han population. A large-scale literature retrieval was conducted using various databases including PubMed, Embase, Wan Fang, and the Chinese National Knowledge Infrastructure (CNKI) up to July 31, 2020, with a total of 2,258 cases and 2,073 controls included. The strength of correlation was assessed by odds ratios (ORs) and 95% confidence intervals (95% CIs). MTHFR C677T showed a significant correlation with increased ASD susceptibility under all genetic models (T vs. C, OR = 1.89, 95% CI 1.28 to 2.79; TT vs. CC: OR = 2.44, 95% CI 1.43 to 4.15; CT vs. CC, OR = 1.73; 95% CI 1.19 to 2.51; CT + TT vs. CC: OR = 2.03, 95% CI 1.31 to 3.15; TT vs. CT + CC, OR = 1.95, 95% CI 1.21 to 3.13). Stratification analysis by region also revealed a consistent association in the Northern Han subgroup, but not in the Southern Han subgroup. Pooled minor allele frequency (MAF) of 30 studies were 45% in Northern Han and 39% in Southern Han. To avoid a possible "false positive report," we further investigated the significant associations observed in the present meta-analysis using the FPRP test, which consolidated the results. In conclusion, MTHFR C677T polymorphism is associated with the increased risk of autism in China, especially in Northern Han. For those mothers and children who are generally susceptible to autism, prenatal folate and vitamin B12 may reduce the risk that children suffer from autism, especially in Northern Han populations. In the future, more well-designed studies with a larger sample size are expected.

Folic acid supplementation and risk for congenital limb reduction defects in China

BACKGROUND

Folic acid (FA) supplementation prevents neural tube defects, but there are mixed results for its ability to prevent limb reduction defects. We examined whether a preventive effect of FA supplementation exists for congenital limb reduction defects in a large population in China.

METHODS

Data from a large population-based cohort study in China were used to evaluate the effects of FA supplementation on birth defects. All births at 20 complete gestational weeks, including live births, stillbirths and pregnancy terminations, and all structural congenital anomalies, regardless of gestational week, were recorded. A total of 247 831 singleton live births delivered at gestational ages of 20-42 weeks to women from northern and southern China with full information on FA intake were included. Limb reduction defects were classified by subtype and maternal FA supplementation.

RESULTS

The prevalence of limb reduction defects was 2.7 per 10 000 births among women who took FA compared with 9.7 per 10 000 births among those who did not take FA in northern China; the prevalence was 4.5 and 3.8 per 10 000 births, respectively, in southern China. In both unadjusted and adjusted analyses, the estimated relative risk for upper limb reduction defects [odds ratio (OR) = 0.17, 95% confidence interval (CI): 0.04, 0.63] and total limb reduction defects (OR = 0.24, 95% CI: 0.08, 0.70) in northern China, but not for lower limb reduction defects ,was significantly decreased in association with FA supplementation in northern China. There was no association between FA supplementation and either an increased or decreased risk for limb reduction defects in southern China.

CONCLUSIONS

FA supplementation successfully reduces the prevalence of limb reduction defects in northern China, whose population has low folate concentrations.

Periconceptional folic acid supplementation and risk of parent-reported asthma in children at 4-6 years of age

BACKGROUND

Folic acid supplementation is universally recommended for women of child-bearing age to prevent fetal neural tube defects (NTDs). Concerns have arisen over the potential risk for childhood allergy and asthma due to folic acid supplementation. We examined whether periconceptional supplementation with low-dose folic acid only was associated with an increased risk for allergy symptoms or asthma in offspring at 4-6 years of age.

METHODS

Out of 247 831 participating women enrolled in 1993-1996, 9090 were randomly selected and their children were followed up in 2000-2001. Information on mothers' demographic characteristics, folic acid supplementation and allergic diseases among children was collected. We used logistic regression to evaluate the association between folic acid intake and risk for allergic disease while adjusting for potential confounding factors.

RESULTS

The rate of allergy symptoms was 1.54% among children whose mothers had taken folic acid compared with 2.04% among those whose mothers had not taken folic acid, and the rate of asthma was 0.92% and 0.88%, respectively. Maternal folic acid supplementation was not associated with risk for allergy symptoms or asthma, with odds ratios (95% CI) of 0.80 (0.58-1.11) and 1.04 (0.67-1.61), respectively. No differences in the occurrence of allergy symptoms or asthma were observed when data were analysed by timing of supplementation or compliance with folic acid supplementation.

CONCLUSIONS

Supplementation with low-dose folic acid only during the periconceptional period did not increase risk for allergy symptoms or asthma in children at 4-6 years of age in a population without staple fortification with folic acid.

Folate of pregnant women after a nationwide folic acid supplementation in China

Folate insufficiency during the periconceptional period increases the risk of neural tube defects (NTDs) in offspring, and folic acid supplementation substantially reduces the risk. Widespread large-scale folic acid supplementation (0.4-mg folic acid tablet) has been adopted as a main strategy to prevent NTDs in China since 2009. We examined folate concentrations in plasma and red blood cells (RBCs) of pregnant women and the factors associated with blood folate concentrations in a population with a high prevalence of NTDs in northern China. A cross-sectional survey was conducted in 2014, and 1,107 pregnant women were recruited from 11 county or city maternal and child health centres across Shanxi province. Microbiological assays were used to determine folate concentrations. Factors associated with blood folate insufficiency were identified. The median (25th and 75th percentiles) folate concentrations were 28.4 (17.6, 45.2) nmol L-1 and 1,001.2 (658.7, 1,402.5) nmol L-1 in plasma and RBCs, respectively. According to the proposed RBC (906 nmol L-1 ) concentrations for optimal NTD prevention, 42.4% participants had RBC folate insufficiency. Rural women had a higher proportion of folate insufficiency than urban women. Folic acid supplementation was the only factor associated with RBC folate insufficiency. A large proportion of women had RBC folate concentrations that are not optimal for the prevention of NTDs despite free access to folic acid supplements. Actions that aim to improve folic acid supplementation compliance are needed to reach the full potential of the nationwide folic acid supplementation programme in terms of NTD prevention.

Sex differences in the prevalence of neural tube defects and preventive effects of folic acid (FA) supplementation among five counties in northern China: results from a population-based birth defect surveillance programme

OBJECTIVES

Sex differences in prevalence of neural tube defects (NTDs) have previously been recognised; however, the different susceptibility of men and women have not been examined in relation to the effects of folic acid (FA) supplementation. We hypothesised that FA may have a disproportionate effect that alters the sex-specific prevalence of NTDs.

SETTING

Data from two time points, before (2003-2004) and after (2011-2016) the start of the supplementation programme, were obtained from a population-based birth defect surveillance programme among five counties in northern China. All live births (28 or more complete gestational weeks), all stillbirths of at least 20 weeks' gestational age and pregnancy terminations at any gestational age following the prenatal diagnosis of NTDs were included.

PARTICIPANTS

A total of 25 249 and 83 996 births before and after the programme were included respectively.

PRIMARY AND SECONDARY OUTCOME MEASURES

The prevalence of NTDs by sex and subtype, Male:female rate ratios and their 95% CI were calculated.

RESULTS

Overall, NTDs were less prevalent among men than among women (rate ratio (RR) 0.92; 95% CI 0.90 to 0.94), so was anencephaly (RR 0.77; 95% CI 0.73 to 0.81) and encephalocele (RR 0.75; 95% CI 0.61 to 0.92), while spina bifida showed a male predominance (RR 1.10; 95% CI 1.05 to 1.15). The overall prevalence of NTDs decreased by 78/10 000 in men and 108.7/10 000 in women from 2003 to 2004 to 2011 to 2016. There was a significant sex difference in the magnitude of reduction, being greater in women than men, particularly for anencephaly.

CONCLUSIONS

The prevalence of NTDs decreased in both sexes after the implementation of a massive FA supplementation programme. While female predominance was observed in open NTDs and total NTDs, they also had a greater rate of decrease in NTDs after the supplementation programme.

A Village-Based Intervention: Promoting Folic Acid Use among Rural Chinese Women

Background: Folic acid supplementation is effective in reducing the risk of neural tube defects (NTDs). However, the use of folic acid is low among rural women in China. Nutrition education can provide information about folic acid and encourage its use. The primary objective of this study was to test the effectiveness of a village-based nutrition intervention on folic acid use among rural women. Methods: Sixty villages were randomly selected using multiple-stage sampling and were divided into control and intervention groups. The intervention included nutritional education at village clinics, written materials, and text messages (SMS). Folic acid use knowledge and behavior was assessed at baseline and after the intervention. Results: Self-reported compliance with folic acid supplement use increased from 17.0%–29.2% at baseline to 41.7%–59.2% one year post-intervention. During the same period, the folic acid knowledge score in the intervention group increased from 3.07 to 3.65, significantly higher than the control group (3.11 to 3.35). Multivariate binary logistic regression showed that the women who received folic acid education and SMS intervention were more likely to comply with folic acid supplement recommendations. Conclusions: The results indicated that an integrated village-based folic acid education intervention may be an effective way of promoting folic acid use for the prevention of NTDs in rural women.

Effectiveness of Folic Acid Fortified Flour for Prevention of Neural Tube Defects in a High Risk Region

Despite efforts to tackle folate deficiency and Neural Tube Defects (NTDs) through folic acid fortification, its implementation is still lacking where it is needed most, highlighting the need for studies that evaluate the effectiveness of folic acid fortified wheat flour in a poor, rural, high-risk, NTD region of China. One of the most affected regions, Shanxi Province, was selected as a case study. A community intervention was carried out in which 16,648 women of child-bearing age received fortified flour (eight villages) and a control group received ordinary flour (three villages). NTD birth prevalence and biological indicators were measured two years after program initiation at endline only. The effect on the NTD burden was calculated using the disability-adjusted life years (DALYs) method. In the intervention group, serum folate level was higher than in the control group. NTDs in the intervention group were 68.2% lower than in the control group (OR = 0.313, 95% CI = 0.207-0473, p < 0.001). In terms of DALYs, burden in intervention group was approximately 58.5% lower than in the control group. Flour fortification was associated with lower birth prevalence and burden of NTDs in economically developing regions with a high risk of NTDs. The positive findings confirm the potential of fortification when selecting an appropriate food vehicle and target region. As such, this study provides support for decision makers aiming for the implementation of (mandatory) folic acid fortification in China.

Effectiveness of Folic Acid Fortified Flour for Prevention of Neural Tube Defects in a High Risk Region

Despite efforts to tackle folate deficiency and Neural Tube Defects (NTDs) through folic acid fortification, its implementation is still lacking where it is needed most, highlighting the need for studies that evaluate the effectiveness of folic acid fortified wheat flour in a poor, rural, high-risk, NTD region of China. One of the most affected regions, Shanxi Province, was selected as a case study. A community intervention was carried out in which 16,648 women of child-bearing age received fortified flour (eight villages) and a control group received ordinary flour (three villages). NTD birth prevalence and biological indicators were measured two years after program initiation at endline only. The effect on the NTD burden was calculated using the disability-adjusted life years (DALYs) method. In the intervention group, serum folate level was higher than in the control group. NTDs in the intervention group were 68.2% lower than in the control group (OR = 0.313, 95% CI = 0.207-0473, p < 0.001). In terms of DALYs, burden in intervention group was approximately 58.5% lower than in the control group. Flour fortification was associated with lower birth prevalence and burden of NTDs in economically developing regions with a high risk of NTDs. The positive findings confirm the potential of fortification when selecting an appropriate food vehicle and target region. As such, this study provides support for decision makers aiming for the implementation of (mandatory) folic acid fortification in China.

Prenatal and neonatal risk factors associated with children's developmental status at ages 4-7: lessons from the Jiangsu China birth defects prevention cohort

BACKGROUND

There is limited information involving population data about the role of maternal health, fetal growth and neonatal health on children's developmental status at ages 4-7 years. Our aim was to determine the contribution of maternal, fetal and neonatal health to developmental status at ages 4-7 years.

METHODS

In this 7-year follow-up prospective cohort study, a sample of 26,803 mothers participated in the beginning. Among their children, 19,187 voluntarily completed the development screening test or the social life ability survey, which were designed for two different age groups (<6 or ≥ 6 years old, respectively). Logistic regression analysis was used to link the data with the prenatal outcome card and interview questionnaire applied to pregnant women in previous study, to the analysis of various related factors such as demographic, socio-economic, disease and menstrual history, marriage and pregnancy care.

RESULT

Univariate and multivariate logistic regression analysis were used separately in two age groups [4-6 (n = 8439) and 6-7 (n = 10,748) years old] to analyse relative factors. Maternal age of 25-30 years, maternal education of high school and greater, family income and not drinking during pregnancy were associated with higher scores in development.

CONCLUSION

Both preconception and pregnancy health education and health care are the important maternal factors closely associated with children's cognitive and social competence. Public health policies for preconception care and public welfare for high-quality childcare are essential for improving children's life.

Prevention of neural tube defects with folic acid: The Chinese experience

Neural tube defects (NTDs) are a group of congenital malformations of the central nervous system that are caused by the closure failure of the embryonic neural tube by the 28^th day of conception. Anencephaly and spina bifida are the two major subtypes. Fetuses with anencephaly are often stillborn or electively aborted due to prenatal diagnosis, or they die shortly after birth. Most infants with spina bifida are live-born and, with proper surgical treatment, can survive into adulthood. However, these children often have life-long physical disabilities. China has one of the highest prevalence of NTDs in the world. Inadequate dietary folate intake is believed to be the main cause of the cluster. Unlike many other countries that use staple fortification with folic acid as the public health strategy to prevent NTDs, the Chinese government provides all women who have a rural household registration and who plan to become pregnant with folic acid supplements, free of charge, through a nation-wide program started in 2009. Two to three years after the initiation of the program, the folic acid supplementation rate increased to 85% in the areas of the highest NTD prevalence. The mean plasma folate level of women during early and mid-pregnancy doubled the level before the program was introduced. However, most women began taking folic acid supplements when they knew that they were pregnant. This is too late for the protection of the embryonic neural tube. In a post-program survey of the women who reported folic acid supplementation, less than a quarter of the women began taking supplements prior to pregnancy, indicating that the remaining three quarters of the fetuses remained unprotected during the time of neural tube formation. Therefore, staple food fortification with folic acid should be considered as a priority in the prevention of NTDs.

Plasma folate levels in early to mid pregnancy after a nation-wide folic acid supplementation program in areas with high and low prevalence of neural tube defects in China

BACKGROUND

Folic acid supplementation is recommended for all women of child-bearing age to prevent neural tube defects (NTDs). A nation-wide folic acid supplementation program was implemented in rural areas of China since 2009; however, changes in plasma folate levels in pregnant women were unknown.

METHODS

A cross-sectional survey was conducted in 2011 to 2012, with 1736 pregnant women enrolled, and results were compared with a previous survey in 2002 to 2004. A microbiological method was used to determine plasma folate levels. Preprogram and postprogram median plasma folate concentrations were compared while stratified by prevalence of NTDs and residence.

RESULTS

In the high NTD prevalence population, plasma folate concentration increased to 33.4 (18.7, 58.4) nmol/L in the postprogram sample, which is 2.9 times of the preprogram. In the low NTD prevalence population, plasma folate increased to 67.9 (44.5, 101.9) nmol/L, which is 1.9 times of the preprogram. Gaps remained in plasma folate levels with respect to prevalence of NTDs and residence. Folic acid supplementation has a strong impact on plasma folate concentrations. Earlier supplementation (before the last menstrual period), increased supplementation frequency and more total days of supplementation were associated with a higher plasma folate concentration as demonstrated in both the high- and low-prevalence populations.

CONCLUSION

Plasma folate levels among pregnant Chinese women increased dramatically after the nation-wide folic acid supplementation program in both rural and urban areas, and in populations of high and low NTD prevalence. The nation-wide program should have a component to ensure that supplementation begins before pregnancy.

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.

Autism spectrum disorders and race, ethnicity, and nativity: a population-based study

OBJECTIVE

Our understanding of the influence of maternal race/ethnicity and nativity and childhood autistic disorder (AD) in African Americans/blacks, Asians, and Hispanics in the United States is limited. Phenotypic differences in the presentation of childhood AD in minority groups may indicate etiologic heterogeneity or different thresholds for diagnosis. We investigated whether the risk of developing AD and AD phenotypes differed according to maternal race/ethnicity and nativity.

METHODS

Children born in Los Angeles County with a primary AD diagnosis at ages 3 to 5 years during 1998-2009 were identified and linked to 1995-2006 California birth certificates (7540 children with AD from a cohort of 1,626,354 births). We identified a subgroup of children with AD and a secondary diagnosis of mental retardation and investigated heterogeneity in language and behavior.

RESULTS

We found increased risks of being diagnosed with AD overall and specifically with comorbid mental retardation in children of foreign-born mothers who were black, Central/South American, Filipino, and Vietnamese, as well as among US-born Hispanic and African American/black mothers, compared with US-born whites. Children of US African American/black and foreign-born black, foreign-born Central/South American, and US-born Hispanic mothers were at higher risk of exhibiting an AD phenotype with both severe emotional outbursts and impaired expressive language than children of US-born whites.

CONCLUSIONS

Maternal race/ethnicity and nativity are associated with offspring's AD diagnosis and severity. Future studies need to examine factors related to nativity and migration that may play a role in the etiology as well as identification and diagnosis of AD in children.

Consumer preferences for micronutrient strategies in China. A comparison between folic acid supplementation and folate biofortification

OBJECTIVE

Despite public health efforts, folate deficiency is still largely prevalent in poor, rural populations and continues to cause a large burden of disease. The present paper determines and compares consumer preferences for two folate strategies: folic acid supplementation v. folate biofortification, i.e. the enhancement of the folate content in staple crops.

DESIGN

Experimental auctions with non-repeated information rounds are applied to rice in order to obtain willingness-to-pay for folate products. Thereby, GM or non-GM folate-biofortified rice (FBR) is auctioned together with rice that is supplemented with free folic acid pills (FAR).

SETTING

Shanxi Province (China) as a high-risk region of folate deficiency.

SUBJECTS

One hundred and twenty-six women of childbearing age, divided into a school (n 60) and market sample (n 66).

RESULTS

Despite differences according to the targeted sample, a general preference for folate biofortification is observed, regardless of the applied breeding technology. Premiums vary between 33·9 % (GM FBR), 36·5 % (non-GM FBR) and 19·0 % (FAR). Zero bidding behaviour as well as the product choice question, respectively, support and validate these findings. The targeted sample, the timing of the auction, the intention to consume GM food and the responsibility for rice purchases are considered key determinants of product choice. A novel ex-post negative valuation procedure shows low consistency in zero bidding.

CONCLUSIONS

While the low attractiveness of FAR provides an additional argument for the limited effectiveness of past folic acid supplementation programmes, the positive reactions towards GM FBR further support its potential as a possible complementary micronutrient intervention.

Changes in folic acid supplementation behaviour among women of reproductive age after the implementation of a massive supplementation programme in China

OBJECTIVE

To examine changes in periconceptional folic acid supplementation behaviour among Chinese women of reproductive age after the implementation of a folic acid supplementation programme.

DESIGN

Two cross-sectional surveys were conducted.

SETTING

One survey was before (2002-2004) and the other was after (2011-2012) implementation of the programme, both were conducted in two areas of China with different prevalence of neural tube defects. Information on supplementation behaviours was collected in face-to-face interviews with women early in their pregnancy.

SUBJECTS

A total of 1257 and 1736 pregnant women participated before and after the programme, respectively.

RESULTS

The rate of periconceptional folic acid supplementation increased from 15 % to 85 % in the high-prevalence population and from 66 % to 92 % in the low-prevalence population. However, more than half of the women began taking the supplement after learning they were pregnant. The proportion of women who began taking folic acid before their last menstrual period decreased after the programme in rural areas with both a high and low prevalence of neural tube defects.

CONCLUSIONS

Although periconceptional folic acid supplementation among Chinese women increased substantially after the programme, supplementation was often initiated too late to be effective in preventing neural tube defects. Educational and promotional campaigns should focus on how to increase the rate of folic acid supplementation before pregnancy.

Folic Acid Supplementation During Early Pregnancy and the Risk of Gestational Hypertension and Preeclampsia

Emerging evidence has suggested that folic acid–containing multivitamins may markedly reduce the risk of gestational hypertension or preeclampsia. We examined whether maternal supplementation with folic acid alone during early pregnancy can prevent the occurrence of gestational hypertension and preeclampsia. The data are from a large population-based cohort study established to evaluate the effectiveness of the campaign to prevent neural tube defects with folic acid supplementation in China. We selected participants who were registered in 2 southern provinces, had exact information on folic acid use, and were not affected by chronic hypertension or diabetes mellitus before 20 weeks gestation. A logistic regression model was used to adjust for the effects of the main potential confounders, including age, body mass index, education, occupation, parity, and multiple births. The study size had 99.9% power (α=0.05) to detect a decrease of 10% over the unexposed rate of 9.4% for gestational hypertension. Among the 193 554 women (47.9% took folic acid, 52.1% did not), the overall incidence of gestational hypertension and preeclampsia was 9.5% and 2.5%, respectively. The incidence of gestational hypertension and preeclampsia was 9.7% and 2.5% for women who took folic acid, and 9.4% and 2.4% for women who did not use it. The adjusted risk ratio associated with folic acid use was 1.08 (95% confidence interval, 1.04–1.11) for gestational hypertension and 1.11 (95% confidence interval, 1.04–1.18) for preeclampsia. Our findings suggest that daily consumption of 400 μg folic acid alone during early pregnancy cannot prevent the occurrence of gestational hypertension and preeclampsia.

Geographical distribution of MTHFR C677T, A1298C and MTRR A66G gene polymorphisms in China: findings from 15357 adults of Han nationality

Background

Methylenetetrahydrofolate reductase (MTHFR) C677T, A1298C and methionine synthase reductase (MTRR) A66G polymorphisms are important genetic determinants for homocysteine (Hcy) levels, and are associated with several disorders. These polymorphisms are heterogeneously distributed worldwide. Our objective was to explore the geographical distributions of these polymorphisms in China.

Methodologies

15357 healthy adults were recruited from 10 regions. Buccal samples were collected and genomic DNA was isolated. Genotyping was performed using the fluorogenic 5′-nuclease assay.

Principal Findings

The prevalence of the three polymorphisms among different populations from China varied significantly and showed apparent geographical gradients. For MTHFR C677T, the frequencies of the 677T allele and the 677TT genotype were significantly higher among northern populations and ranged from the lowest values (24.0% and 6.4%, respectively) in Hainan (southern) to the highest values (63.1% and 40.8%, respectively) in Shandong (northern). For MTHFR A1298C, the 1298C allele and the 1298CC genotype frequencies were significantly higher among southern populations and increased from low values (13.1% and 1.4%, respectively) in Shandong to high values (25.7% and 6.7%, respectively) in Hainan. For A66G, the 66G allele and the 66GG genotype frequencies increased from lower values (23.7% and 5.4%, respectively) in Shandong to higher values (29.2% and 8.6%, respectively) in Hainan. The overall frequency of the 677T allele, 677TT genotype, 1298C allele, 1298CC genotype, 66G allele and 66GG genotype in the Chinese Han population was 45.2%, 23.2%, 18.6%, 3.9%, 25.7%, and 6.6%, respectively. No gender differences were found in the prevalence of both the MTHFR C677T and MTRR A66G polymorphisms.

Conclusions

This study indicates that there are marked geographical variations in the prevalence of the three polymorphisms among Chinese Han populations. Our baseline data may be useful for future researches in related fields.

Geographic and urban-rural disparities in the total prevalence of neural tube defects and their subtypes during 2006-2008 in China: a study using the hospital-based birth defects surveillance system

BACKGROUND

Previous reports on the prevalence of neural tube defects (NTDs) in China did not include cases of NTDs that were less than 28 weeks of gestational age (GA) and hence did not accurately reflect the total prevalence of NTDs or the geographic and urban-rural disparities in their prevalence. This article includes cases of NTDs that were less than 28 weeks of GA.

METHODS

Data used in this study were collected from 2006 to 2008 using a nationwide hospital-based registry, the Chinese Birth Defects Monitoring Network. The total prevalence ratio (PR) of NTDs and their subtypes, the ratios of PR (PRR), and 95% confidence intervals (CI) were used to analyse geographic disparities at both the regional (north, south) and provincial levels and to analyse disparities between rural and urban areas.

RESULTS

Overall, the total PR of NTDs was 14.0 per 10,000 births. The PRR of NTDs of rural women between the north and south region was 2.26 (95% CI: 2.04-2.52), which was much higher than that of urban women (PRR: 1.56, 95% CI: 1.41-1.72). The three subtypes of NTDs had different geographic distribution at the level of province. The urban-rural PRR of NTDs was 2.14 (95% CI: 1.94-2.34) in the north but only 1.47 (95% CI: 1.31-1.66) in the south.

CONCLUSIONS

There is a high total prevalence of NTDs, which remains one of the major public health concerns in China. Eliminating the geographic and urban-rural disparities in the disease burden is a priority for future intervention.

Effect on risk of anencephaly of gene-nutrient interactions between methylenetetrahydrofolate reductase C677T polymorphism and maternal folate, vitamin B12 and homocysteine profile

OBJECTIVE

To evaluate the effects on anencephaly risk of the interaction between the maternal profile of folate, vitamin B12 and homocysteine and the 677C→T polymorphism in the gene encoding methylenetetrahydrofolate reductase (MTHFR).

DESIGN

Case-control study paired (1:1) on maternity clinic, date of birth and state of residence. Cases of anencephaly were identified using the Registry of the Mexican Neural Tube Defect Epidemiological Surveillance System. Case and control mothers were selected from the same maternity departments. All mothers completed a structured questionnaire and blood samples were obtained to determine the MTHFR 677C→T polymorphism and biochemical profile.

SETTING

Mexico, Puebla and Guerrero states, Mexico.

SUBJECTS

A total of 151 mothers of cases and controls were enrolled from March 2000 to February 2001. We had complete information on biochemical profile and MTHFR C677T polymorphism for ninety-eight mothers of cases and ninety-one mothers of controls.

RESULTS

The adjusted models show that the risk of anencephaly in mothers with 677TT genotype was reduced by 18 % (OR = 0·82; 95 % CI 0·72, 0·94) for each 1 ng/ml increment in serum folate. In terms of tertiles, mothers with 677TT genotype with serum folate levels in the upper tertile (>14·1 ng/ml) had a 95 % lower risk to have a child with anencephaly than mothers with serum folate levels in the first and second tertiles (P trend = 0·012).

CONCLUSIONS

Our data agree with the hypothesis of a gene-nutrient interaction between MTHFR 677C→T polymorphism and folate status. We observed a protective effect on anencephaly risk only in mothers with 677TT genotype as serum folate levels increased.

Tea drinking as a risk factor for neural tube defects in northern China

BACKGROUND

Tea catechins inhibit the activity of the enzyme dihydrofolate reductase, which catalyzes the inactive form of folate 7,8-dihydrofolate to the active form of folate 5,6,7,8-tetrahydrofolate. This inhibition leads to disturbance of the folate metabolic pathway and to lower bioavailability of folate to cells; therefore, it may increase the risk of neural tube defects (NTDs) in a developing embryo. We examined the association between tea drinking during the periconceptional period and the risk of NTDs.

METHODS

Cases were fetuses or neonates with an NTD as ascertained through a population-based surveillance system in 4 rural counties of Shanxi Province in northern China during 2002 through 2007. Controls were term infants without congenital malformations. Demographic, reproductive, and exposure data were obtained through a face-to-face interview.

RESULTS

A total of 631 NTD cases and 857 controls were included in the analysis. Compared with women who did not drink tea during the periconceptional period (487 cases and 688 controls), women who drank tea daily (20 cases and 9 controls) had a 3-fold increased risk (odds ratio = 3.1 [95% confidence interval = 1.4-7.0]) of having an NTD-affected pregnancy. The elevated risk associated with daily tea drinking remained after adjusting for maternal age, educational level, occupation, and periconceptional folic acid supplementation (3.4 [1.4-8.3]). The association was present for all 3 major subtypes of NTDs (ie, anencephaly, spina bifida, and encephalocele).

CONCLUSIONS

Daily tea drinking during the periconceptional period was associated with an elevated risk of NTDs in this Chinese population.

Conceiving risk, divergent responses: perspectives on the construction of risk of FASD in six countries

Conceptualizations of risks related to women's alcohol use during pregnancy, and the attendant response to preventing fetal alcohol spectrum disorder (FASD), are examined in six countries: the United States, Canada, the United Kingdom, Uganda, Uruguay, and China. Considerable differences were found in how risks were conceptualized across countries and in contextual factors that influence research, prevention, and intervention efforts. Differences in conceptualizations were also apparent within countries. Differences also existed in the degree to which the issue of drinking during pregnancy has been minimized or amplified and in whether and how responses are linked to treatment or other public health interventions.

Maternal prepregnancy body mass index and risk of neural tube defects: A population-based case-control study in Shanxi province, China

BACKGROUND

Many studies from the Western world have indicated that maternal obesity is associated with an increased risk of neural tube defects (NTDs). However, few reports have been available on this association from Asian populations. Our aim was to examine the relationship between maternal prepregnancy body mass index (BMI) and the risk of NTDs in a population of northern China.

METHODS

Data were derived from an ongoing population-based case-control study of birth defects in Shanxi province, China. Subjects were 511 NTD cases and 687 controls selected from the same population between January 2003 and June 2007. BMI was based on maternal height and prepregnancy weight as reported within 1 week of delivery.

RESULTS

We found no significantly increased risk of NTDs for obese women (adjusted odds ratio [OR], 0.65; 95% confidence interval [CI], 0.29-1.49) or for underweight women (adjusted OR, 1.00; 95% CI, 0.62-1.62) relative to normal-weight women. We found a significantly reduced risk of overall NTDs (adjusted OR, 0.56; 95% CI, 0.41-0.76) and anencephaly (adjusted OR, 0.40; 95% CI, 0.26-0.62) for overweight women compared to normal-weight women.

CONCLUSIONS

Our results do not support the association between maternal prepregnancy obesity and increased risk of overall NTDs or of any subtype of NTDs in the Chinese population.

Plasma folate status and dietary folate intake among Chinese women of childbearing age

Maternal folic acid deficiency is an underlying risk for neural tube defects (NTDs). China has one of the highest prevalences of NTDs, and the prevalence rates of NTDs vary by region. We characterized plasma folate level and dietary folate intake among Chinese women of childbearing age by region (North and South, East and West, urban and rural) to provide evidence for establishing policy to prevent NTDs. A total of 1003 women of childbearing age from five provinces in China were interviewed. Fasting blood samples were collected. Plasma folate concentrations were determined by a microbiological assay. Dietary intake data were collected using a 24-h recall. Both the plasma folate concentrations and dietary folate intake of women in the South (25.9 nmol L(-1) and 211.0 microg day(-1)) were higher than those of women in the North (13.3 nmol L(-1) and 189.2 microg day(-1)). In the North, plasma folate concentrations and dietary folate intake of women in rural areas were lower than those of women in urban areas, whereas, in the South, an opposite pattern was observed. No difference was found between women in the East and West, in either the North or South regions. Plasma folate and dietary folate intake among Chinese women of childbearing age were suboptimal and varied by region. Different folic acid supplementation approaches and dosage should be undertaken to improve folate status of women in different areas. Particular attention should be paid to women in the North, especially in northern rural areas.

High prevalence of orofacial clefts in Shanxi Province in northern China, 2003-2004

Shanxi Province in northern China has been identified as an area with the highest prevalence of neural tube defects in the world; however, few reports exist on the prevalence of orofacial clefts (OFC). We examined the prevalence of OFC and their association with selected characteristics. Data came from a population-based birth defects surveillance system in four counties of Shanxi Province. The system captures information on all live births, stillbirths of at least 20 weeks gestation, and pregnancy terminations at any gestational age after prenatal diagnosis of a birth defect. Out of 25,355 births in 2003-2004, 83 cases with orofacial clefts were identified resulting in a birth prevalence of 3.27 per 1,000. Other major external birth defects were present in 12 (14.5%) OFC cases. Cleft lip with palate (CLP), cleft lip alone (CL) and cleft palate alone (CP) accounted for 62.0%, 29.6% and 8.4% of OFC cases without additional external defects, respectively. The male to female ratio was 1.04 (95%CI: 0.67-1.60) for all OFC, 1.46 (95%CI: 0.80-2.68) for CLP, 1.23 (95%CI: 0.52-2.91) for CL, 0.46 (95%CI: 0.08-2.51) for CP without additional major external defects, and 0.31(95%CI: 0.08-1.13) for OFC with additional external defects. The prevalence of OFC without additional external defects was increased with decreased maternal age (P < 0.05) and increased maternal education (P < 0.05). The birth prevalence of OFC in Shanxi Province of northern China is among the highest worldwide. Further studies are required to define the factors associated with excess risk of clefts.