Folate concentrations during pregnancy and autistic traits in the offspring. The Generation R Study

Newborn Dried Blood Spot Folate in Relation to Maternal Self-reported Folic Acid Intake, Autism Spectrum Disorder, and Developmental Delay

BACKGROUND

Maternal folic acid intake has been associated with decreased risk for neurodevelopmental disorders including autism spectrum disorder (ASD). Genetic differences in folate metabolism could explain some inconsistencies. To our knowledge, newborn folate concentrations remain unexamined.

METHODS

We measured folate in archived newborn dried blood spots of children from the CHARGE (Childhood Autism Risks from Genetics and the Environment) case-control study who were clinically confirmed at 24-60 months to have ASD (n = 380), developmental delay (n = 128), or typical development (n = 247). We quantified monthly folic acid intake from maternally-reported supplements and cereals consumed during pregnancy and 3 months prior. We assessed associations of newborn folate with maternal folic acid intake and with ASD or developmental delay using regression. We stratified estimates across maternal and child MTHFR genotypes.

RESULTS

Among typically developing children, maternal folic acid intake in prepregnancy and each pregnancy month and prepregnancy prenatal vitamin intake were positively associated with newborn folate. Among children with ASD, prenatal vitamin intake in pregnancy months 2-9 was positively associated with newborn folate. Among children with developmental delay, maternal folic acid and prenatal vitamins during the first pregnancy month were positively associated with neonatal folate. Associations differed by MTHFR genotype. Overall, neonatal folate was not associated with ASD or developmental delay, though we observed associations with ASD in children with the MTHFR 677 TT genotype (odds ratio: 1.76, 95% CI = 1.19, 2.62; P for interaction = 0.08).

CONCLUSION

Maternal prenatal folic acid intake was associated with neonatal folate at different times across neurodevelopmental groups. Neonatal folate was not associated with reduced ASD risk. MTHFR genotypes modulated these relationships.

Food, nutrition, and autism: from soil to fork

Food and nutrition-related factors have the potential to impact development of autism spectrum disorder (ASD) and quality of life for people with ASD, but gaps in evidence exist. On 10 November 2022, Tufts University's Friedman School of Nutrition Science and Policy and Food and Nutrition Innovation Institute hosted a 1-d meeting to explore the evidence and evidence gaps regarding the relationships of food and nutrition with ASD. This meeting report summarizes the presentations and deliberations from the meeting. Topics addressed included prenatal and child dietary intake, the microbiome, obesity, food-related environmental exposures, mechanisms and biological processes linking these factors and ASD, food-related social factors, and data sources for future research. Presentations highlighted evidence for protective associations with prenatal folic acid supplementation and ASD development, increases in risk of ASD with maternal gestational obesity, and the potential for exposure to environmental contaminants in foods and food packaging to influence ASD development. The importance of the maternal and child microbiome in ASD development or ASD-related behaviors in the child was reviewed, as was the role of discrimination in leading to disparities in environmental exposures and psychosocial factors that may influence ASD. The role of child diet and high prevalence of food selectivity in children with ASD and its association with adverse outcomes were also discussed. Priority evidence gaps identified by participants include further clarifying ASD development, including biomarkers and key mechanisms; interactions among psychosocial, social, and biological determinants; interventions addressing diet, supplementation, and the microbiome to prevent and improve quality of life for people with ASD; and mechanisms of action of diet-related factors associated with ASD. Participants developed research proposals to address the priority evidence gaps. The workshop findings serve as a foundation for future prioritization of scientific research to address evidence gaps related to food, nutrition, and ASD.

Examining associations of folic acid supplements administered to mothers during pre-conceptional and prenatal periods with autism spectrum disorders in their offspring: insights from a multi-center study in China

Objective

To investigate the relationship between maternal folic acid (FA) supplementation during the pre-conceptional and prenatal periods and the subsequent risk of autism spectrum disorder (ASD) in offspring.

Methods

A total of 6,049 toddlers aged 16-30 months were recruited from August 2016 to March 2017 for this cross-sectional study conducted in China. The parents of the enrolled toddlers provided information on maternal supplemental FA, socio-demographic information, and related covariates. Standard diagnostic procedures were implemented to identify toddlers with ASD.

Results

Among the 6,049 children included in the study, consisting of 3,364 boys with an average age of 22.7 ± 4.1 months, a total of 71 children (1.2%) were diagnosed with ASD. Mothers who did not consume FA supplements during the prenatal period were found to have a significantly increased risk of having offspring with ASD, in comparison to those who were exposed to FA supplements (odds ratio [OR] = 2.47). However, we did not find a similar association during the pre-conceptional period. Compared to mothers who consistently used FA supplements from pre-conception to the prenatal period, those who never used FA supplements were statistically significantly associated with a higher risk of ASD in their offspring (OR = 2.88).

Conclusion

This study indicated that providing continuous maternal FA supplementation during the pre-conceptional and prenatal periods may decrease the risk of ASD in offspring. The prenatal period is considered to be the most crucial time for intervention.

Pre-autism: What a paediatrician should know about early diagnosis of autism‎

Autism, also known as an autism spectrum disorder, is a complex neurodevelopmental disorder usually diagnosed in the first three years of a child's life. A range of symptoms characterizes it and can be diagnosed at any age, including adolescence and adulthood. However, early diagnosis is crucial for effective management, prognosis, and care. Unfortunately, there are no established fetal, prenatal, or newborn screening programs for autism, making early detection difficult. This review aims to shed light on the early detection of autism prenatally, natally, and early in life, during a stage we call as "pre-autism" when typical symptoms are not yet apparent. Some fetal, neonatal, and infant biomarkers may predict an increased risk of autism in the coming baby. By developing a biomarker array, we can create an objective diagnostic tool to diagnose and rank the severity of autism for each patient. These biomarkers could be genetic, immunological, hormonal, metabolic, amino acids, acute phase reactants, neonatal brainstem function biophysical activity, behavioral profile, body measurements, or radiological markers. However, every biomarker has its accuracy and limitations. Several factors can make early detection of autism a real challenge. To improve early detection, we need to overcome various challenges, such as raising community awareness of early signs of autism, improving access to diagnostic tools, reducing the stigma attached to the diagnosis of autism, and addressing various culturally sensitive concepts related to the disorder.

Maternal Serum Vitamin B12 during Pregnancy and Offspring Autism Spectrum Disorder

This study examined the association between maternal serum vitamin B12 levels during early pregnancy and offspring autism spectrum disorders (ASD) and subtypes. Based on a Finnish national birth cohort, case offspring (n = 1558) born in 1987-2007 and diagnosed with ASD by 2015 were matched with one control on date of birth, sex and place of birth. Maternal vitamin B12 levels were measured during first and early second trimesters of pregnancy. High maternal vitamin B12 levels (≥81th percentile) was associated with increased risk for offspring childhood autism, adjusted odds ratio, 1.59, 95% confidence interval 1.06-2.41 (p = 0.026). No significant associations were observed between maternal vitamin B12 levels and offspring Asperger's or pervasive developmental disorder/NOS.

Amino Acids, B Vitamins, and Choline May Independently and Collaboratively Influence the Incidence and Core Symptoms of Autism Spectrum Disorder

Autism spectrum disorder (ASD) is a developmental disorder of variable severity, characterized by difficulties in social interaction, communication, and restricted or repetitive patterns of thought and behavior. In 2018, the incidence of ASD was 2.4 times higher than estimated in 2000. Behavior and brain development abnormalities are present in the complex disorder of ASD. Nutritional status plays a key role in the incidence and severity of the core symptoms of ASD. The aim of this study was to review the available peer-reviewed studies that evaluated the relationship between amino acids, choline, B vitamins, and ASD incidence and/or severity of symptoms. Through examining plasma profiles, urine samples, and dietary intake, researchers found that low choline, abnormal amino acid, and low B vitamin levels were present in children with ASD compared to those without ASD. The evidence supports the need for future research that implements simultaneous supplementation of all essential nutrients in individuals with ASD and among prenatal mothers. Future evidence could lead to scientific breakthroughs, ultimately reducing the rates of ASD incidence and severity of symptoms by applying nutritional interventions in at-risk populations.

Maternal Dietary Patterns during Pregnancy and Child Autism-Related Traits: Results from Two US Cohorts

We examined the relationship between maternal intake of established dietary patterns and child autism-related outcomes in two prospective cohorts in the United States. Participants were drawn from the Early Autism Risk Longitudinal Investigation (EARLI, n = 154) and the Nurses' Health Study II (NHSII, n = 727). Dietary information was collected via food frequency questionnaires (FFQs) and used to calculate the empirical dietary inflammatory pattern (EDIP), Alternative Healthy Eating Index (AHEI), Western and Prudent dietary patterns, and the alternative Mediterranean Diet (aMED) score. Primary analyses examined associations with continuous autism-related traits as measured by the Social Responsiveness Scale (SRS), and secondary analyses with autism spectrum disorder (ASD) diagnosis. We used crude and multivariable quantile regression fixed at the 50th percentile to examine associations between quartiles of dietary patterns and SRS scores, and logistic regression to examine associations with ASD diagnosis. There was suggestion of a positive association with the Western diet (Q4 vs. Q1, ß = 11.19, 95% CI: 3.30, 19.90) in EARLI, though the association was attenuated with adjustment for total energy intake, and no clear associations were observed with other dietary patterns and ASD diagnosis or SRS scores. Further work is needed to better understand the role of maternal dietary patterns in ASD and related outcomes.

Prenatal folic acid supplementation and autism spectrum disorder in 3-year-old offspring: the Japan environment and children's study

OBJECTIVE

We evaluated the relationship between prenatal folic acid supplementation and autism spectrum disorder (ASD) in 3-year-old offspring.

METHODS

We used data from the Japan Environment and Children's Study, a nationwide prospective birth cohort study. We analyzed the data to determine the association between folic acid supplement use and the incidence of ASD in offspring, and classified participants into three groups based on the time of initiation of folic acid supplementation, as follows: (1) preconception users of folic acid supplements and (2) post-conception users, and (3) non-users. The dietary folate intake of study participants was also classified into three groups (<200 µg, 200 µg to <400 µg, ≥400 µg).

RESULTS

Overall, 361 offspring of 96,931 participants with single pregnancies were diagnosed with ASD (0.37%). A total of 7,046 participants (7.3%) used folic acid supplements before conception, 29,984 (30.9%) took them after detection of pregnancy, and 59,901 (61.8%) never received them. Multivariate logistic regression analyses demonstrated no association between prenatal folic acid supplementation and ASD in offspring (preconception use: adjusted odds ratio [AOR], 1.189; 95% confidence interval [CI], 0.819-1.727 and post-conception use: AOR, 1.072; 95% CI, 0.840-1.368); additionally, no association was observed with the use of folic acid supplements and/or multivitamin supplements (preconception use: AOR, 1.273; 95% CI, 0.921-1.760 and post-conception use: AOR, 1.132; 95% CI, 0.885-1.449). Moreover, no significant association was observed in participants with combined prenatal supplement use and dietary folate intake.

CONCLUSIONS

Maternal use of folic acid supplements from the pre- or post-conception period was not significantly associated with ASD in 3-year-old offspring in Japan. Evaluation of the dietary folate intake from preconception also showed no significant association.

Association of the Maternal Folic Acid Supplementation with the Autism Spectrum Disorder: A Systematic Review

OBJECTIVE

 To analyze the scientific production regarding maternal folic acid (FA) supplementation and its relationship with autistic spectrum disorder (ASD).

DATA SOURCES

 We performed unrestricted electronic searches in the BIREME virtual bank, Virtual Health Library (VHL) and Medical Literature Analysis and Retrieval System Online (MEDLINE/PubMed) databases.

SELECTION OF STUDIES

 For sample selection, articles that met the proposed objectives were included, published in English, Spanish and Portuguese, the use of Health Sciences Descriptors (DeCS): autistic OR autism AND autism spectrum disorder AND folic acid, AND, with the use of the Medical Subject Headings (MeSH): autistic OR autism AND autistic spectrum disorder AND folic acid.

DATA COLLECTION

 Data extraction was performed by the reviewers with a preestablished data collection formulary.

DATA SYNTHESIS

 The Preferred Reporting Items for Systematic Review and Meta-Analysis Protocols (PRISMA-P) was used based on a checklist with 27 items and a 4-step flowchart.

RESULTS

 A total of 384 articles was found by the search strategies, of which 17 were eligible following the pre-established criteria. The main findings of the present review point to maternal FA supplementation in the pre-conception period and beginning of pregnancy as a protective effect in relation to ASD, which should be indicated in this period as prevention to the problem.

CONCLUSION

 According to the research analyzed, more studies are necessary to know its effects on pregnancy, since the consumption of excessive FA may not be innocuous.

Neurodevelopmental effects of maternal folic acid supplementation: a systematic review and meta-analysis

Folic acid, a water-soluble vitamin B nutrient, plays an important role not only in maintaining a healthy pregnancy but also in offspring brain development and function, however, it remains unclear whether maternal folic acid (FA) supplementation associated with the risk of different postnatal neurodevelopmental outcomes. Here, we performed a systematic review and meta-analysis on the impact of maternal FA supplementation on a wide range of postnatal neurodevelopmental outcomes which include intellectual development, risk of autistic traits, ADHD, behavior, language, and psychomotor problems, using studies extracted from the following databases, including MEDLINE, Web of Science, Cochrane Library, Scopus, EMBASE, and PsychInfo. Thirty-two cohort studies and seven case-control studies were included in this meta-analysis. In the present study, we found that prenatal FA supplementation had a positive impact on offspring's neurodevelopmental outcomes, including improved intellectual development and reduced risk of autism traits, ADHD, behavioral, and language problems. We also found that FA over-supplementation was not associated with an improvement in offspring's brain development, and may have a negative impact on offspring's neurodevelopmental outcomes. This study proved the first panoramic review on the relationship of FA supplementation with offspring's neurodevelopment. Further studies focusing on different dosages and periods of FA supplementation are needed.Supplemental data for this article is available online at https://doi.org/10.1080/10408398.2021.1993781 .

Folinic Acid as Adjunctive Therapy in Treatment of Inappropriate Speech in Children with Autism: A Double-Blind and Placebo-Controlled Randomized Trial

This is a double-blind, placebo-controlled randomized trial to investigate the potential therapeutic effects of folinic acid/placebo as an adjuvant to risperidone on inappropriate speech and other behavioral symptoms of autism spectrum disorder (ASD). Fifty-five ASD children (age (mean ± standard deviation) = 13.40 ± 2.00; male/female: 35/20) were evaluated for behavioral symptoms at baseline, week 5, and week 10 using the aberrant behavior checklist-community (ABC-C). Folinic acid dosage was 2 mg/kg up to 50 mg per day for the entire course of the study. The repeated measures analysis showed significant effect for time × treatment interaction on inappropriate speech (F = 3.51; df = 1.61; P = 0.044), stereotypic behavior (F = 4.02; df = 1.37; P = 0.036), and hyperactivity/noncompliance (F = 6.79; df = 1.66; P = 0.003) subscale scores. In contrast, no significant effect for time × treatment interaction was found on lethargy/social withdrawal (F = 1.06; df = 1.57; P = 0.336) and irritability (F = 2.86; df = 1.91; P = 0.064) subscale scores. Our study provided preliminary evidence suggesting that folinic acid could be recommended as a beneficial complementary supplement for alleviating speech and behavioral symptoms in children with ASD.Clinical trial registeration: This trial was registered in the Iranian Registry of Clinical Trials ( www.irct.ir ; No. IRCT20090117001556N114).

Maternal vitamin B12, folate during pregnancy and neurocognitive outcomes in young adults of the Pune Maternal Nutrition Study (PMNS) prospective birth cohort: study protocol

INTRODUCTION

The Developmental Origins of Health and Disease (DOHaD) hypothesis proposes that intrauterine and early life exposures significantly influence fetal development and risk for disease in later life. Evidence from prospective birth cohorts suggests a role for maternal B₁₂ and folate in influencing neurocognitive outcomes in the offspring. In the Indian setting, B₁₂ deficiency is common during the pregnancy while rates of folate deficiency are lower. The long-term influences of maternal nutrition during the pregnancy on adult neurocognitive outcomes have not been examined. The Pune Maternal Nutrition Study (PMNS) is a preconceptional birth cohort into its 24th year and is considered a unique resource to study the DOHaD hypothesis. We found an association between maternal B₁₂ status in pregnancy and child's neurocognitive status at 9 years of age. We now plan to assess neurocognitive function and MRI measurements of brain structural-functional connectivity at young adult age to study its association with maternal nutritional exposures during the pregnancy.

METHODS AND ANALYSIS

As part of ongoing prospective follow-up in young adults of the PMNS at the Diabetes Unit, KEM Hospital Research Center, Pune India, the following measurements will be done: neurocognitive performance (Standardised Tests of Intelligence, Verbal and Visual Memory, Attention and Executive Functions), temperament (Adult Temperament Questionnaire), psychopathology (Brief Symptom Inventory and Clinical Interview on Mini Neuropsychiatric Interview 7.0). Brain MRI for structural T1, resting-state functional connectivity and diffusion tensor imaging will be performed on a subset of the cohort (selected based on exposure to a lower or higher maternal B₁₂ status at 18 weeks of pregnancy).

ETHICS AND DISSEMINATION

The study is approved by Institutional ethics committee of KEM Hospital Research Center, Pune. The results will be shared at national and international scientific conferences and published in peer-reviewed scientific journals.

TRIAL REGISTRATION NUMBER

NCT03096028.

Folic Acid and Autism: A Systematic Review of the Current State of Knowledge

Folic acid has been identified to be integral in rapid tissue growth and cell division during fetal development. Different studies indicate folic acid’s importance in improving childhood behavioral outcomes and underline its role as a modifiable risk factor for autism spectrum disorders. The aim of this systematic review is to both elucidate the potential role of folic acid in autism spectrum disorders and to investigate the mechanisms involved. Studies have pointed out a potential beneficial effect of prenatal folic acid maternal supplementation (600 µg) on the risk of autism spectrum disorder onset, but opposite results have been reported as well. Folic acid and/or folinic acid supplementation in autism spectrum disorder diagnosed children has led to improvements, both in some neurologic and behavioral symptoms and in the concentration of one-carbon metabolites. Several authors report an increased frequency of serum auto-antibodies against folate receptor alpha (FRAA) in autism spectrum disorder children. Furthermore, methylene tetrahydrofolate reductase (MTHFR) polymorphisms showed a significant influence on ASD risk. More clinical trials, with a clear study design, with larger sample sizes and longer observation periods are necessary to be carried out to better evaluate the potential protective role of folic acid in autism spectrum disorder risk.

The Association of Prenatal Vitamins and Folic Acid Supplement Intake with Odds of Autism Spectrum Disorder in a High-Risk Sibling Cohort, the Early Autism Risk Longitudinal Investigation (EARLI)

We examined maternal prenatal vitamin use or supplemental folic acid intake during month one of pregnancy for association with autism spectrum disorder (ASD) in the Early Autism Risk Longitudinal Investigation, an enriched-risk pregnancy cohort. Total folic acid intake was calculated from monthly prenatal vitamins, multivitamins, and other supplement reports. Clinical assessments through age 3 years classified children as ASD (n = 38) or non-ASD (n = 153). In pregnancy month one, prenatal vitamin use (59.7%) was not significantly associated with odds of ASD (OR = 0.70, 95%CI 0.32, 1.53). Sample size was limited and residual confounding was possible. Given the estimated effect sizes in this and previous work, prenatal vitamin intake during early pregnancy could be a clinically useful preventative measure for ASD.

Maternal Dietary Factors and the Risk of Autism Spectrum Disorders: A Systematic Review of Existing Evidence

Prenatal maternal diet is a critical factor in offspring neurodevelopment. Emerging evidence suggests that prenatal diet may also play a role in the etiology autism spectrum disorder (ASD). This review summarizes studies published in English that examined prenatal nutrients or maternal diet in association with ASD from PubMed as of July 2020. Thiry-six studies from nine countries were included in this systematic review; these focused on multivitamin (n = 5), prenatal vitamin (n = 3), folic acid (FA; n = 14), Vitamin D (n = 11), polyunsaturated fatty acid or fish/supplement intake (n = 7), iron (n = 3), Vitamin B12 (n = 1), calcium (n = 1), magnesium (n = 1), and broad maternal dietary habits (n = 3). Overall, higher or moderate intake of prenatal/multivitamin, FA, and Vitamin D was associated with reductions in odds of ASD, though results have not been uniform and there is a need to clarify differences in findings based on biomarkers versus reported intake. Evidence was inconclusive or insufficient for other nutrients. Differences in the timing and measurement of these dietary factors, as well as potential residual confounding, may contribute to existing discrepancies. Key areas for future research to better understand the role of maternal diet in ASD include the need to address potential critical windows, examine the combined effect of multiple nutrients, and consider interactions with genetic or environmental factors. LAY SUMMARY: Maternal diet during pregnancy is important for child neurodevelopment. We reviewed 36 studies examining maternal diet and autism spectrum disorder (ASD) and found that prenatal vitamin/multivitamin use and adequate intake of folic acid and Vitamin D were each associated with lower likelihood of having a child with ASD. Future studies on these and other dietary factors are needed to better understand the role of maternal diet in the development of ASD. Autism Res 2020, 13: 1634-1658. © 2020 International Society for Autism Research and Wiley Periodicals LLC.

A prospective birth cohort study on cord blood folate subtypes and risk of autism spectrum disorder

BACKGROUND

We previously reported that extremely high concentrations of maternal plasma folate were associated with increased risk of autism spectrum disorder (ASD) in children. This study explored whether specific types of folate in cord blood have differential association with ASD.

OBJECTIVES

In the Boston Birth Cohort (BBC), we assessed the association between cord blood unmetabolized folic acid (UMFA), 5-methyl tetrahydrofolate (THF), and total folate and a child's ASD risk. In a subset, we explored whether the association between UMFA and ASD risk can be affected by the dihydrofolate reductase (DHFR) genotype and cord plasma creatinine. We also examined prenatal correlates of cord UMFA concentrations.

METHODS

This report included 567 BBC children (92 ASD, 475 neurotypical), who were recruited at birth and prospectively followed at the Boston Medical Center. ASD was defined from International Classification of Diseases (ICD)-9 and ICD-10 codes documented in electronic medical records.

RESULTS

Children with cord UMFA in the highest, versus lowest quartile, had a greater ASD risk (adjusted OR, aORquartile4: 2.26; 95% CI: 1.08, 4.75). When stratified by race/ethnicity, the association was limited to 311 (45 ASD) Black children (aORquartile4: 9.85; 95% CI: 2.53, 38.31); a test of interaction between race/ethnicity and cord UMFA concentrations was significant (P = 0.007). The UMFA-ASD association in Black children slightly attenuated after adjusting for cord plasma creatinine (P = 0.05). There was no significant association between cord 5-methyl THF, total folate, DHFR genotype, and ASD risk. Cord total folate and maternal supplement intake during second trimester were associated with higher cord UMFA.

CONCLUSIONS

Higher concentrations of cord UMFA, but not 5-methyl THF or total folate, were associated with a greater risk of ASD in Black children. This study in a preterm-birth-enriched cohort raises more questions than it could answer and underscores the need for additional investigations on the sources and role of cord UMFA in children's neurodevelopmental outcomes and underlying mechanisms.

Maternal oversupplementation with folic acid and its impact on neurodevelopment of offspring

Folic acid, a B vitamin, is vital for early neurodevelopment and is well known for its protective effect against neural tube defects. Various national health agencies worldwide recommend that women of childbearing age take approximately 0.4 to 1 mg of supplemental folic acid daily to reduce the risk of neural tube defects in offspring. Several countries have tried to promote folic acid intake through mandatory fortification programs to reduce neural tube defects. Supplementation combined with mandatory fortification of foods has led to high levels of folic acid and related metabolites in women of childbearing age. Recent studies have reported that oversupplementation, defined as exceeding either the recommended dietary allowance or the upper limit of the daily reference intake of folic acid, may have negative effects on human health. This review examines whether maternal oversupplementation with folic acid affects the neurodevelopment of offspring. Data from animal studies suggest there are behavioral, morphological, and molecular changes in the brain of offspring. Additional studies are required to determine both the dosage of folic acid and the timing of folic acid intake needed for optimal neurodevelopment in humans.

Association of maternal prenatal folic acid intake with subsequent risk of autism spectrum disorder in children: A systematic review and meta-analysis

BACKGROUND

A number of studies have explored the link of antenatal folic acid (FA) intake with autism spectrum disorder (ASD) in children, with inconsistent findings. Therefore, we conducted a systematic review and meta-analysis of relevant studies to elucidate the actual association between maternal FA intake during the prenatal period and the risk of ASD in offspring.

METHODS

PubMed, EMBASE, PsycINFO, Scopus, Web of Science, and Cochrane Library were searched up to June 7, 2018, without language restriction. The random-effects model was applied to summarize results. The adjusted odds ratios (ORs) and hazard ratios (HRs) were pooled separately.

RESULTS

Eight observational studies (a total of 13 reports; 840,776 children and 7127 cases) were included. FA intake was mainly estimated from self-report of mothers or available databases. The results of overall analysis from 6 studies (9 reports) combined by OR and 2 studies (4 reports) presenting HR showed that the likelihoods of ASD in offspring whose mothers were prenatally exposed to FA did not vary significantly compared with those in offspring of mothers without such exposure (OR = 0.91, 95% CI: 0.73-1.13 and HR = 0.66, 95% CI: 0.38-1.17, respectively). Further analysis revealed that the primary outcome of the meta-analysis was stable regardless of the study design, and not unduly affected by any single report. Additionally, no publication bias was observed, and the findings of overall analysis were in agreement with those of subgroup analyses.

CONCLUSIONS

This study does not provide support for the association between maternal FA intake during the prenatal period and the reduced risk of ASD in children. However, in view of the types and limited number of studies in the literature, more investigation is needed to confirm the findings of this meta-analysis.

Does high-dose gestational folic acid increase the risk for autism? The birth order hypothesis

There has been a dramatic increase in the incidence of autism spectrum disorder (ASD) in recent decades but the causes have not been elucidated. To date, numerous studies have shown that the FDA-recommended doses of folic acid (400 mcg/d) render a protective effect against ASD. Yet, a recent prospective study has claimed that while self-reported folic acid supplementation was associated with decreased risk of ASD, very high levels of maternal plasma folate levels (<60.3 nmol/L) were associated with 2.5 time increased risk of ASD. This study has led to high levels of public anxiety because many women use high dose folic acid to prevent neural tube defects. We hypothesize that because ASD children have been documented to be much more likely to be first or second born, and women consume significantly more folic acid during their first and second pregnancies, the claim that high dose folic acid causes ASD is based on a previously unrecognized birth order bias. This article presents evidence for the wrong claim that high dose folic acid causes ASD. The question whether high exposure level of folic acid is associated with increased risk of ASD is not merely a theoretical issue, because many women at increased risk for NTD in their offspring need substantially higher daily doses of folic acid (1 mg, or 5 mg), than the FDA-recommended 400 mcg daily.

Nutritional Supplements During Gestation and Autism Spectrum Disorder: What Do We Really Know and How Far Have We Gone?

Nutritional interventions are gaining remarkable attention as complementary management options for autism. Our aim is to provide literature data about the impact of the administration of dietary supplements during pregnancy on the risk of autism spectrum disorder in the offspring. A comprehensive search was undertaken by 2 reviewers independently using PubMed as the medical database source. Prospective clinical and experimental studies were considered and no year-of-publication restriction was placed. We were able to identify 4 basic (conducted in rodents) and 3 clinical research papers fulfilling our selection criteria. Supplements studied included folic acid, iron, multivitamins, choline, vitamin D, and docosahexaenoic acid. Choline and folic acid had a significant impact on the expression of autism-related genes. However, from a clinical point of view, prenatal folate administration did not reduce the risk of autism. Similarly, iron had no significant impact, while the use of multivitamins in moderate frequency had a protective effect. The use of vitamin D and docosahexaenoic acid during gestation decreased the incidence of autism in animal models. In conclusion, available data are controversial and cannot change current routine practice. More large-scale prospective studies are needed to identify the real effect of nutritional supplements and also optimize their administration.Key teaching pointsMultivitamins use during pregnancy can exert a protective effect on the risk of autism, although depending on the frequency of use. Nevertheless, prenatal iron and folate were not shown to have any significant impact.Research based on animal models showed that choline and folic acid can have a significant impact on the expression of autism-related genes in a sex-specific manner.Furthermore, the use of vitamin D and docosahexaenoic acid during gestation seem to decrease the incidence of autism in animal offspring.In the future, more clinical, large-scale prospective and methodologically homogenous clinical studies are needed to further investigate the effect of the periconceptional use of nutritional supplements on autism risk.

Preconception and Prenatal Nutrition and Neurodevelopmental Disorders: A Systematic Review and Meta-Analysis

Preconception and prenatal nutrition is critical for fetal brain development. However, its associations with offspring neurodevelopmental disorders are not well understood. This study aims to systematically review the associations of preconception and prenatal nutrition with offspring risk of neurodevelopmental disorders. We searched the PubMed and Embase for articles published through March 2019. Nutritional exposures included nutrient intake or status, food intake, or dietary patterns. Neurodevelopmental outcomes included autism spectrum disorders (ASD), attention deficit disorder-hyperactivity (ADHD) and intellectual disabilities. A total of 2169 articles were screened, and 20 articles on ASD and 17 on ADHD were eventually reviewed. We found an overall inverse association between maternal folic acid or multivitamin supplementation and children’s risk of ASD; a meta-analysis including six prospective cohort studies estimated an RR of ASD of 0.64 (95% CI: 0.46, 0.90). Data on associations of other dietary factors and ASD, ADHD and related outcomes were inconclusive and warrant future investigation. Future studies should integrate comprehensive and more objective methods to quantify the nutritional exposures and explore alternative study design such as Mendelian randomization to evaluate potential causal effects.

Maternal and neonatal 25-hydroxyvitamin D concentrations and school-age lung function, asthma and allergy. The Generation R Study

BACKGROUND

Vitamin D deficiency in early life might affect the developing lung and immune system, and subsequently influence the risk of asthma and allergy in later life.

OBJECTIVE

We examined the associations of 25-hydroxyvitamin D concentrations in mid-gestation and at birth with lung function, asthma, inhalant allergic sensitization and inhalant allergy at school-age.

METHODS

This study among 4951 children and their mothers was embedded in a population-based prospective cohort in Rotterdam, the Netherlands. Maternal venous blood samples in mid-gestation and umbilical cord blood samples at birth were used to determine 25-hydroxyvitamin D concentrations. At age 10 years, lung function was measured by spirometry, current asthma and physician-diagnosed inhalant allergy by questionnaire, and inhalant allergic sensitization by skin prick tests. We used multivariable regression models to examine associations.

RESULTS

Higher 25-hydroxyvitamin D concentrations in mid-gestation were associated with a higher forced vital capacity (FVC), but a lower forced expiratory volume in 1 second/FVC (FEV₁ /FVC) and a lower forced expiratory flow after exhaling 75% of FVC (FEF₇₅ ) (Z-score differences [95% CI] 0.02 [0.00, 0.03], -0.02 [-0.03, -0.01] and -0.01 [-0.03, -0.00], respectively, per 10 nmol/L 25-hydroxyvitamin D), but not with asthma. Furthermore, higher 25-hydroxyvitamin D concentrations in mid-gestation were associated with an increased risk of inhalant allergy (Odds Ratio [95% CI] 1.07 [1.02, 1.12]), but not with inhalant allergic sensitization. After additional adjustment for child's 25-hydroxyvitamin D concentrations at the age of 6 years, only the associations of 25-hydroxyvitamin D concentrations in mid-gestation with FEV₁ /FVC and FEF₇₅ remained. We did not find consistent associations of 25-hydroxyvitamin D concentrations at birth with respiratory or allergy outcomes.

CONCLUSION AND CLINICAL RELEVANCE

Our results suggest that maternal 25-hydroxyvitamin D concentrations in mid-gestation may influence lung development. The clinical implications of the observed associations remain unclear.

Association of Maternal Prenatal Vitamin Use With Risk for Autism Spectrum Disorder Recurrence in Young Siblings

Importance

Maternal use of folic acid supplements has been inconsistently associated with reduced risk for autism spectrum disorder (ASD) in the child. No study to date has examined this association in the context of ASD recurrence in high-risk families.

Objective

To examine the association between maternal prenatal vitamin use and ASD recurrence risk in younger siblings of children with ASD.

Design, Setting, and Participants

This prospective cohort study analyzed data from a sample of children (n = 332) and their mothers (n = 305) enrolled in the MARBLES (Markers of Autism Risk in Babies: Learning Early Signs) study. Participants in the MARBLES study were recruited at the MIND Institute of the University of California, Davis and were primarily from families receiving services for children with ASD in the California Department of Developmental Services. In this sample, the younger siblings at high risk for ASD were born between December 1, 2006, and June 30, 2015, and completed a final clinical assessment within 6 months of their third birthday. Prenatal vitamin use during pregnancy was reported by mothers during telephone interviews. Data analysis for this study was conducted from January 1, 2017, to December 3, 2018.

Main Outcomes and Measures

Autism spectrum disorder, other nontypical development (non-TD), and typical development (TD) were algorithmically defined according to Autism Diagnostic Observation Schedule and Mullen Scales of Early Learning subscale scores.

Results

After exclusions, the final sample comprised 241 younger siblings, of which 140 (58.1%) were male and 101 (41.9%) were female, with a mean (SD) age of 36.5 (1.6) months. Most mothers (231 [95.9%]) reported taking prenatal vitamins during pregnancy, but only 87 mothers (36.1%) met the recommendations to take prenatal vitamins in the 6 months before pregnancy. The prevalence of ASD was 14.1% (18) in children whose mothers took prenatal vitamins in the first month of pregnancy compared with 32.7% (37) in children whose mothers did not take prenatal vitamins during that time. Children whose mothers reported taking prenatal vitamins during the first month of pregnancy were less likely to receive an ASD diagnosis (adjusted relative risk [RR], 0.50; 95% CI, 0.30-0.81) but not a non-TD 36-month outcome (adjusted RR, 1.14; 95% CI, 0.75-1.75) compared with children whose mothers reported not taking prenatal vitamins. Children in the former maternal prenatal vitamin group also had statistically significantly lower autism symptom severity (adjusted estimated difference, -0.60; 95% CI, -0.97 to -0.23) and higher cognitive scores (adjusted estimated difference, 7.1; 95% CI, 1.2-13.1).

Conclusions and Relevance

Maternal prenatal vitamin intake during the first month of pregnancy may reduce ASD recurrence in siblings of children with ASD in high-risk families. Additional research is needed to confirm these results; to investigate dose thresholds, contributing nutrients, and biologic mechanisms of prenatal vitamins; and to inform public health recommendations for ASD prevention in affected families.

Review and meta-analysis found that prenatal folic acid was associated with a 58% reduction in autism but had no effect on mental and motor development

AIM

The impact of prenatal folic acid on children's neurodevelopment and the risk of autism spectrum disorder (ASD) remain unclear and this review and meta-analysis aimed to quantify any associations.

METHODS

We systematically searched PubMed, Scopus and The Cochrane Library until June 2018 with no language restrictions. Standardised mean differences and odds ratio with 95% confidence intervals are used to describe any associations between folic acid and mental development, motor development and ASD.

RESULTS

The search strategy identified 647 papers and 16 were finally included in the meta-analysis after the application of the exclusion criteria. These provided a total cohort size of 756 365 children aged 11 months to 15 years from 10 countries. The main finding was that prenatal use of folic acid was associated with a 58% reduction in the risk of ASD in children. We were surprised that better scores for mental development were associated with low prenatal exposure to folic acid.

CONCLUSION

Although the results should be interpreted with caution, they showed that routine prenatal supplements of folic acid were associated with significantly lower levels of ASD. Further studies are needed to reach a firm conclusion, given the multifactorial aetiology of neurodevelopment.

Prenatal Primary Prevention of Mental Illness by Micronutrient Supplements in Pregnancy

Genes, infection, malnutrition, and other factors affecting fetal brain development are a major component of risk for a child's emotional development and later mental illnesses, including schizophrenia, bipolar disorder, and autism. Prenatal interventions to ameliorate that risk have yet to be established for clinical use. A systematic review of prenatal nutrients and childhood emotional development and later mental illness was performed. Randomized trials of folic acid, phosphatidylcholine, and omega-3 fatty acid supplements assess effects of doses beyond those adequate to remedy deficiencies to promote normal fetal development despite genetic and environmental risks. Folic acid to prevent neural tube defects is an example. Vitamins A and D are currently recommended at maximum levels, but women's incomplete compliance permits observational studies of their effects. Folic acid and phosphatidylcholine supplements have shown evidence for improving childhood emotional development associated with later mental illnesses. Vitamins A and D decreased the risk for schizophrenia and autism in retrospective observations. Omega-3 fatty acid supplementation during early pregnancy increased the risk for schizophrenia and increased symptoms of attention deficit hyperactivity disorder, but in later pregnancy it decreased childhood wheezing and premature birth. Studies are complicated by the length of time between birth and the emergence of mental illnesses like schizophrenia, compared with anomalies like facial clefts identified at birth. As part of comprehensive maternal and fetal care, prenatal nutrient interventions should be further considered as uniquely effective first steps in decreasing risk for future psychiatric and other illnesses in newborn children. [AJP at 175: Remembering Our Past As We Envision Our Future July 1959: Longitudinal Observations of Biological Deviations in a Schizophrenic Infant Barbara Fish described the course of an infant born with fluctuating motor problems who developed schizophrenia. (Am J Psychiatry 1959; 116:25-31 )].

Acetaminophen, antibiotics, ear infection, breastfeeding, vitamin D drops, and autism: an epidemiological study

BACKGROUND

While many studies have examined environmental risk factors for autism spectrum disorder (ASD), much of the research focus has been on prenatal or perinatal factors. Yet, the postnatal environment may affect the risk of ASD as well.

OBJECTIVE

To determine whether a set of five postnatal variables are associated with ASD. These variables are: acetaminophen exposure, antibiotic exposure, incidence of ear infection, decreased duration of breastfeeding, and decreased consumption of oral vitamin D drops.

MATERIALS AND METHODS

An Internet-based survey was conducted. Participants were parents living in the USA with at least one biological child between 3 and 12 years of age. Potential participants were informed about the survey via postings on social media, websites, and listservs and were offered an opportunity to participate in a raffle as well. Participants were also recruited through the Interactive Autism Network.

RESULTS

There were 1,741 completed survey responses. After exclusions, there remained 1,001 responses associated with children with ASD (cases) and 514 responses associated with children who do not have ASD (controls). In this data set, doses of postnatal acetaminophen (adjusted odds ratio [aOR] 1.016, CI: 1.003-1.032, p=0.026), courses of postnatal antibiotics (aOR 1.103, CI: 1.046-1.168, p<0.001), incidence of postnatal ear infection (aOR 1.137, CI: 1.046-1.236, p=0.003), and decreased duration of breastfeeding (aOR 0.948, CI: 0.932-0.965, p<0.001) are all associated with ASD when adjusted for eight demographic variables. A weak association between oral vitamin D drop exposure and ASD was also found when adjusted for breastfeeding and demographics (aOR 1.025, CI: 0.995-1.056, p=0.102).

CONCLUSION

This study adds to evidence that postnatal acetaminophen use, postnatal antibiotic use, incidence of ear infection, and early weaning are associated with an increased risk of ASD. It also finds that postnatal oral vitamin D drops are weakly associated with ASD when adjusted for breastfeeding and demographics.

Understanding environmental contributions to autism: Causal concepts and the state of science

The complexity of neurodevelopment, the rapidity of early neurogenesis, and over 100 years of research identifying environmental influences on neurodevelopment serve as backdrop to understanding factors that influence risk and severity of autism spectrum disorder (ASD). This Keynote Lecture, delivered at the May 2016 annual meeting of the International Society for Autism Research, describes concepts of causation, outlines the trajectory of research on nongenetic factors beginning in the 1960s, and briefly reviews the current state of this science. Causal concepts are introduced, including root causes; pitfalls in interpreting time trends as clues to etiologic factors; susceptible time windows for exposure; and implications of a multi-factorial model of ASD. An historical background presents early research into the origins of ASD. The epidemiologic literature from the last fifteen years is briefly but critically reviewed for potential roles of, for example, air pollution, pesticides, plastics, prenatal vitamins, lifestyle and family factors, and maternal obstetric and metabolic conditions during her pregnancy. Three examples from the case-control CHildhood Autism Risks from Genes and the Environment Study are probed to illustrate methodological approaches to central challenges in observational studies: capturing environmental exposure; causal inference when a randomized controlled clinical trial is either unethical or infeasible; and the integration of genetic, epigenetic, and environmental influences on development. We conclude with reflections on future directions, including exposomics, new technologies, the microbiome, gene-by-environment interaction in the era of -omics, and epigenetics as the interface of those two. As the environment is malleable, this research advances the goal of a productive and fulfilling life for all children, teen-agers and adults. Autism Res 2018, 11: 554-586. © 2018 International Society for Autism Research, Wiley Periodicals, Inc.

LAY SUMMARY

This Keynote Lecture, delivered at the 2016 meeting of the International Society for Autism Research, discusses evidence from human epidemiologic studies of prenatal factors contributing to autism, such as pesticides, maternal nutrition and her health. There is no single cause for autism. Examples highlight the features of a high-quality epidemiology study, and what comprises a compelling case for causation. Emergent research directions hold promise for identifying potential interventions to reduce disabilities, enhance giftedness, and improve lives of those with ASD.

Association of Maternal Use of Folic Acid and Multivitamin Supplements in the Periods Before and During Pregnancy With the Risk of Autism Spectrum Disorder in Offspring

IMPORTANCE

The association of maternal use of folic acid and multivitamin supplements before and during pregnancy with the risk of autism spectrum disorder (ASD) in offspring is unclear.

OBJECTIVE

To examine the associations between the use of maternal folic acid and multivitamin supplements before and during pregnancy and the risk of ASD in offspring.

DESIGN, SETTING, AND PARTICIPANTS

A case-control cohort study of 45 300 Israeli children born between January 1, 2003, and December 31, 2007, were followed up from birth to January 26, 2015, for the risk of ASD. The cases were all children diagnosed with ASD and the controls were a random sample of 33% of all live-born children.

EXPOSURES

Maternal vitamin supplements were classified for folic acid (vitamin B9), multivitamin supplements (Anatomical Therapeutic Chemical A11 codes vitamins A, B, C, and D), and any combination thereof exposed in the intervals before and during pregnancy.

MAIN OUTCOMES AND MEASURES

The association between maternal vitamin supplementation and the risk of ASD in offspring was quantified with relative risks (RRs) and their 95% CIs fitting Cox proportional hazards regression models adjusted for confounders. Sensitivity analyses were performed to test the robustness of the results.

RESULTS

Of the 45 300 children in the study (22 090 girls and 23 210 boys; mean [SD] age, 10.0 [1.4] years at the end of follow-up), 572 (1.3%) received a diagnosis of ASD. Maternal exposure to folic acid and/or multivitamin supplements before pregnancy was statistically significantly associated with a lower likelihood of ASD in the offspring compared with no exposure before pregnancy (RR, 0.39; 95% CI, 0.30-0.50; P < .001). Maternal exposure to folic acid and/or multivitamin supplements during pregnancy was statistically significantly associated with a lower likelihood of ASD in offspring compared with no exposure during pregnancy (RR, 0.27; 95% CI, 0.22-0.33; P < .001). Corresponding RRs were estimated for maternal exposure to folic acid before pregnancy (RR, 0.56; 95% CI, 0.42-0.74; P = .001), maternal exposure to folic acid during pregnancy (RR, 0.32; 95% CI, 0.26-0.41; P < .001), maternal exposure to multivitamin supplements before pregnancy (RR, 0.36; 95% CI, 0.24-0.52; P < .001), and maternal exposure to multivitamin supplements during pregnancy (RR, 0.35; 95% CI, 0.28-0.44; P < .001). The results generally remained statistically significant across sensitivity analyses.

CONCLUSIONS AND RELEVANCE

Maternal exposure to folic acid and multivitamin supplements before and during pregnancy is associated with a reduced risk of ASD in the offspring compared with the offspring of mothers without such exposure.

Folinic acid improves verbal communication in children with autism and language impairment: a randomized double-blind placebo-controlled trial

We sought to determine whether high-dose folinic acid improves verbal communication in children with non-syndromic autism spectrum disorder (ASD) and language impairment in a double-blind placebo control setting. Forty-eight children (mean age 7 years 4  months; 82% male) with ASD and language impairment were randomized to receive 12 weeks of high-dose folinic acid (2 mg kg^-1 per day, maximum 50 mg per day; n=23) or placebo (n=25). Children were subtyped by glutathione and folate receptor-α autoantibody (FRAA) status. Improvement in verbal communication, as measured by a ability-appropriate standardized instrument, was significantly greater in participants receiving folinic acid as compared with those receiving placebo, resulting in an effect of 5.7 (1.0,10.4) standardized points with a medium-to-large effect size (Cohen's d=0.70). FRAA status was predictive of response to treatment. For FRAA-positive participants, improvement in verbal communication was significantly greater in those receiving folinic acid as compared with those receiving placebo, resulting in an effect of 7.3 (1.4,13.2) standardized points with a large effect size (Cohen's d=0.91), indicating that folinic acid treatment may be more efficacious in children with ASD who are FRAA positive. Improvements in subscales of the Vineland Adaptive Behavior Scale, the Aberrant Behavior Checklist, the Autism Symptom Questionnaire and the Behavioral Assessment System for Children were significantly greater in the folinic acid group as compared with the placebo group. There was no significant difference in adverse effects between treatment groups. Thus, in this small trial of children with non-syndromic ASD and language impairment, treatment with high-dose folinic acid for 12 weeks resulted in improvement in verbal communication as compared with placebo, particularly in those participants who were positive for FRAAs.

Joint effects of prenatal air pollutant exposure and maternal folic acid supplementation on risk of autism spectrum disorder

Independent studies report that periconceptional folic acid (FA) may decrease the risk of autism spectrum disorder (ASD) while exposure to air pollution may increase ASD risk. We examined the joint effects of gestational FA and air pollution exposures in association with ASD. We studied 346 ASD cases and 260 typically developing controls from the CHARGE case-control study. Self-reported FA intake for each month of pregnancy was quantified. Estimates of exposure to near roadway air pollution (NRP) and criteria air pollutant measures were assigned based on maternal residential history. Among mothers with high FA intake (>800 μg) in the first pregnancy month, exposure to increasing levels of all air pollutants, except ozone, during the first trimester was associated with decreased ASD risk, while increased ASD risk was observed for the same pollutant among mothers with low FA intake (≤800 μg). This difference was statistically significant for NO2 (e.g., NO2 and low FA intake: OR = 1.53 (0.91, 2.56) vs NO2 and high FA intake: OR = 0.74 (0.46, 1.19), P-interaction = 0.04). Mothers exposed to higher levels (≥ median) of any air pollutant during the first trimester of pregnancy and who reported low FA intake were at a higher ASD risk compared to mothers exposed to lower levels of that air pollutant and who reported high first month FA intake. Joint effects showed significant (alpha < 0.10) departures from expected interaction for NRP and NO2 . Our results suggest that periconceptional FA intake may reduce ASD risk in those with high prenatal air pollution exposure. Further study is needed to replicate these findings in larger sample sizes and to understand mechanisms of this potential relationship.. Autism Res 2018, 11: 69-80. © 2017 International Society for Autism Research, Wiley Periodicals, Inc.

LAY SUMMARY

We examined interactions between periconceptional folic acid (FA) and air pollution exposure on risk of ASD. Mothers exposed to higher levels of air pollution during the first trimester of pregnancy and who reported low supplemental FA intake during the first pregnancy month were at a higher ASD risk compared to mothers exposed to lower levels of air pollution and who reported high first month FA intake. Our results suggest that periconceptional FA intake may reduce ASD risk in those with high prenatal air pollution exposure.

Maternal Multivitamin Intake, Plasma Folate and Vitamin B12 Levels and Autism Spectrum Disorder Risk in Offspring

BACKGROUND

To examine the prospective association between multivitamin supplementation during pregnancy and biomarker measures of maternal plasma folate and vitamin B₁₂ levels at birth and child's Autism Spectrum Disorder (ASD) risk.

METHODS

This report included 1257 mother-child pairs, who were recruited at birth and prospectively followed through childhood at the Boston Medical Center. ASD was defined from diagnostic codes in electronic medical records. Maternal multivitamin supplementation was assessed via questionnaire interview; maternal plasma folate and B₁₂ were measured from samples taken 2-3 days after birth.

RESULTS

Moderate (3-5 times/week) self-reported supplementation during pregnancy was associated with decreased risk of ASD, consistent with previous findings. Using this as the reference group, low (≤2 times/week) and high (>5 times/week) supplementation was associated with increased risk of ASD. Very high levels of maternal plasma folate at birth (≥60.3 nmol/L) had 2.5 times increased risk of ASD [95% confidence interval (CI) 1.3, 4.6] compared to folate levels in the middle 80th percentile, after adjusting for covariates including MTHFR genotype. Similarly, very high B₁₂ (≥536.8 pmol/L) showed 2.5 times increased risk (95% CI 1.4, 4.5).

CONCLUSION

There was a 'U shaped' relationship between maternal multivitamin supplementation frequency and ASD risk. Extremely high maternal plasma folate and B₁₂ levels at birth were associated with ASD risk. This hypothesis-generating study does not question the importance of consuming adequate folic acid and vitamin B₁₂ during pregnancy; rather, raises new questions about the impact of extremely elevated levels of plasma folate and B₁₂ exposure in-utero on early brain development.

Antenatal nutritional supplementation and autism spectrum disorders in the Stockholm youth cohort: population based cohort study

Objective To determine whether nutritional supplementation during pregnancy is associated with a reduced risk of autism spectrum disorder (ASD) with and without intellectual disability in offspring.Design Observational prospective cohort study using multivariable logistic regression, sibling controls, and propensity score matching.Setting Stockholm County, Sweden.Participants 273 107 mother-child pairs identified through population registers. The study sample was restricted to children who were aged 4 to 15 years by the end of follow-up on 31 December 2011 and were born between 1996 and 2007.Exposures Multivitamin, iron, and folic acid supplement use was reported at the first antenatal visit.Main outcome measure Diagnosis of ASD with and without intellectual disability in children determined from register data up to 31 December 2011.Results Prevalence of ASD with intellectual disability was 0.26% (158 cases in 61 934) in the maternal multivitamin use group and 0.48% (430 cases in 90 480) in the no nutritional supplementation use group. Maternal multivitamin use with or without additional iron or folic acid, or both was associated with lower odds of ASD with intellectual disability in the child compared with mothers who did not use multivitamins, iron, and folic acid (odds ratio 0.69, 95% confidence interval 0.57 to 0.84). Similar estimates were found in propensity score matched (0.68, 0.54 to 0.86) and sibling control (0.77, 0.52 to 1.15) matched analyses, though the confidence interval for the latter association included 1.0 and was therefore not statistically significant. There was no consistent evidence that either iron or folic acid use were inversely associated with ASD prevalence.Conclusions Maternal multivitamin supplementation during pregnancy may be inversely associated with ASD with intellectual disability in offspring. Further scrutiny of maternal nutrition and its role in the cause of autism is recommended.

The association between maternal use of folic acid supplements during pregnancy and risk of autism spectrum disorders in children: a meta-analysis

Previous reviews have been conducted to evaluate the association between maternal use of folic acid supplements during pregnancy and risk of autism spectrum disorders (ASD) in children, with no definitive conclusion. We therefore conducted a more comprehensive meta-analysis to reassess the relationship between folic acid and the risk of ASD. The electronic databases PubMed, Web of Knowledge, and Wanfang Data were carefully searched to find eligible studies as recent as March 2017. A random effects model was used to combine the relative risk (RR) with 95% confidence intervals (CI). Sensitivity analysis and publication bias were conducted. A total of 12 articles with 16 studies comprising 4514 ASD cases were included in this report. It was found that supplementation with folic acid during pregnancy could reduce the risk of ASD [RR = 0.771, 95% CI = 0.641–0.928, I² = 59.7%, P_{heterogeneity} = 0.001] as compared to those women without folic acid supplementation. The associations were significant among Asian, European, and American populations. In summary, this comprehensive meta-analysis suggested that maternal use of folic acid supplements during pregnancy could significantly reduce the risk of ASD in children regardless of ethnicity, as compared to those women who did not supplement with folic acid.

Combined Prenatal Pesticide Exposure and Folic Acid Intake in Relation to Autism Spectrum Disorder

BACKGROUND

Maternal folic acid (FA) protects against developmental toxicity from certain environmental chemicals.

OBJECTIVE

We examined combined exposures to maternal FA and pesticides in relation to autism spectrum disorder (ASD).

METHODS

Participants were California children born from 2000-2007 who were enrolled in the Childhood Autism Risks from Genetics and the Environment (CHARGE) case-control study at age 2-5 y, were clinically confirmed to have ASD (n=296) or typical development (n=220), and had information on maternal supplemental FA and pesticide exposures. Maternal supplemental FA and household pesticide product use were retrospectively collected in telephone interviews from 2003-2011. High vs. low daily FA intake was dichotomized at 800μg (median). Mothers' addresses were linked to a statewide database of commercial applications to estimate agricultural pesticide exposure.

RESULTS

High FA intake (≥800μg) during the first pregnancy month and no known pesticide exposure was the reference group for all analyses. Compared with this group, ASD was increased in association with <800μg FA and any indoor pesticide exposure {adjusted odds ratio [OR]=2.5 [95% confidence interval (CI): 1.3, 4.7]} compared with low FA [OR=1.2 (95% CI: 0.7, 2.2)] or indoor pesticides [OR=1.7 (95% CI: 1.1, 2.8)] alone. ORs for the combination of low FA and regular pregnancy exposure (≥6 mo) to pet pesticides or to outdoor sprays and foggers were 3.9 (95% CI: 1.4, 11.5) and 4.1 (95% CI: 1.7, 10.1), respectively. ORs for low maternal FA and agricultural pesticide exposure 3 mo before or after conception were 2.2 (95% CI: 0.7, 6.5) for chlorpyrifos, 2.3 (95% CI: 0.98, 5.3) for organophosphates, 2.1 (95% CI: 0.9, 4.8) for pyrethroids, and 1.5 (95% CI: 0.5, 4.8) for carbamates. Except for carbamates, these ORs were approximately two times greater than those for either exposure alone or for the expected ORs for combined exposures under multiplicative or additive models.

CONCLUSIONS

In this study population, associations between pesticide exposures and ASD were attenuated among those with high versus low FA intake during the first month of pregnancy. Confirmatory and mechanistic studies are needed. https://doi.org/10.1289/EHP604.

Prevention of behavioral deficits in rats exposed to folate receptor antibodies: implication in autism

Folate receptor alpha (FRα) autoantibodies have been associated with fetal abnormalities and cerebral folate deficiency-related developmental disorders. Over 70% of the children with autism spectrum disorders (ASD) are positive for these autoantibodies and high-dose folinic acid is beneficial in treating these children. Here we show that antibodies (Abs) to the rat FRα administered during gestation produce communication, learning and cognitive deficits in a rat model that can be prevented by folinic acid and dexamethasone. FRα Ab can trigger inflammation as well as block folate transport to the fetus and to the developing brain to produce the functional deficits. In humans, exposure to FRα autoantibodies during fetal development and infancy could contribute to brain dysfunction such as that seen in ASD and other developmental disorders. Identifying women positive for the autoantibody and treating them with high-dose folinic acid along with other interventions to lower the autoantibody titer are effective strategies that may be considered to reduce the risk of having a child with developmental deficits.

[Association between maternal folate supplementation during pregnancy and the risk of autism spectrum disorder in the offspring: a Meta analysis]

OBJECTIVE

To quantitatively and comprehensively investigate the association between maternal folate supplementation during pregnancy and the risk of autism spectrum disorder (ASD) in the offspring.

METHODS

PubMed, Embase, Scopus, Cochrane Library, EBSCO, CNKI, Wanfang Data, VIP Database, and Chinese Biomedical Database were searched to collect the articles on maternal folate supplementation during pregnancy and the risk of ASD in children. Odds ratio (OR) and 95% confidence interval (CI) were used to determine the effect size. Stata 12.0 software was used for the Meta analysis. Publication bias evaluation and sensitivity analysis were also performed.

RESULTS

A total of 10 articles were included according to the inclusion and exclusion criteria, including 15 studies which involved 4 459 cases and 1 225 835 controls. The Meta analysis showed that maternal folate supplementation during pregnancy significantly reduced the risk of ASD in the offspring in the total population (OR=0.798, 95%CI: 0.669-0.952, P=0.012). The subgroup analysis revealed that maternal folate supplementation during pregnancy was associated with a reduced risk of ASD in the offspring in both the Asian population (OR=0.664, 95%CI: 0.428-1.032, P=0.069) and the Western population (OR=0.817, 95%CI: 0.671-0.996, P=0.045).

CONCLUSIONS

Maternal folate supplementation during pregnancy may reduce the risk of ASD in the offspring, especially in the Western population.

New Perspective on Impact of Folic Acid Supplementation during Pregnancy on Neurodevelopment/Autism in the Offspring Children - A Systematic Review

It has been conclusively established that folic acid supplementation prior to and during early pregnancy (up to 12 weeks of gestation) can prevent neural tube defects (NTDs). We hypothesized that folate effects may extend from neuro-structural defects to alterations in neuro-behavioural and emotional skills including autism spectrum disorders (ASDs) and other developmental disorders. The objective of this review was to comprehensively evaluate evidence on the impact of folic acid on neurodevelopment other than NTDs. We conducted an online search of relevant literature compiled by the National Library of Medicine from Medline and EMBASE (searched on Dec 31, 2014: http://www.ncbi.nlm.nih.gov/entrez/query/fcgi and http://www.elsevier.com/online-tools/embase). We first created 3 files (search restricted to English literature) using the following key words: 1) folate or folic acid (171322 papers identified by this search); 2) maternal or pregnancy or pregnant or gestation or gestational or prenatal or antenatal or periconception or periconceptional (1349219 papers identified by this search); and 3) autism or autism spectrum disorders or developmental delay or development or neurodevelopment or mental or cognitive or language or personal-social or gross motor or fine motor or behaviour or intellectual or intelligence or Bayley Scale (8268145 papers identified by this search). We then merged the 3 files and reviewed the papers that addressed these three issues simultaneously. A total of 22 original papers that examined the association between folic acid supplementation in human pregnancy and neurodevelopment/autism were identified after the screening, with 15 studies showing a beneficial effect of folic acid supplementation on neurodevelopment/autism, 6 studies showed no statistically significant difference, while one study showed a harmful effect in > 5 mg folic acid supplementation/day during pregnancy. Folic acid supplementation in pregnancy may have beneficial effects on the neurodevelopment of children beyond its proven effect on NTDs.

Associations of maternal and fetal 25-hydroxyvitamin D levels with childhood lung function and asthma: the Generation R Study

BACKGROUND

Exposure to low levels of vitamin D in fetal life might be a risk factor for childhood asthma.

OBJECTIVE

We examined whether 25-hydroxyvitamin D levels in mid-gestation and at birth were associated with higher airway resistance and inflammation, and increased risks of wheezing and asthma in school-age children.

METHODS

We performed a population-based prospective cohort study among 3130 mothers and their children. Maternal blood samples in mid-gestation and umbilical cord blood samples at birth were used to determine 25-hydroxyvitamin D levels. At age of 6, airway resistance (Rint) was measured by interrupter technique and airway inflammation by fractional exhaled nitric oxide (FENO) using NIOX chemiluminescence analyser. Wheezing and asthma were prospectively assessed by annual questionnaires until age 6.

RESULTS

Maternal levels of 25-hydroxyvitamin D in mid-gestation were not associated with Rint, FeNO, wheezing patterns, or asthma. Children in the lowest tertile of 25-hydroxyvitamin D levels at birth had a higher Rint (Z-score (95% confidence interval [95% CI]): -0.42 (-0.84, -0.01), P-value for trend< 0.05), compared to those in the highest tertile group. The effect estimate attenuated when child's current 25-hydroxyvitamin D level was taken into account [Z-score (95% CI): -0.55 (-1.08, 0.01)].

CONCLUSION AND CLINICAL RELEVANCE

Low levels of 25-hydroxyvitamin D at birth were associated with a higher airway resistance in childhood. Additional adjustment for child's current 25-hydroxyvitamin D level reduced the effect size of the association. Further studies are needed to replicate these findings and to examine mechanisms underlying the observed association and the long-term consequences.

Associations of maternal and fetal 25-hydroxyvitamin D levels with childhood eczema: The Generation R Study

BACKGROUND

Exposure to low levels of vitamin D in fetal life might affect the developing immune system, and subsequently the risk of childhood eczema. We examined whether 25-hydroxyvitamin D levels in mid-gestation and at birth were associated with the risk of eczema until the age of 4 years.

METHODS

In a population-based prospective cohort study of 3019 mothers and their children, maternal blood samples in mid-gestation and umbilical cord blood samples at birth were used to determine 25-hydroxyvitamin D levels (severely deficient <25.0 nmol/l, deficient 25.0-49.9 nmol/l, sufficient 50.0-74.9 nmol/l, optimal ≥75.0 nmol/l). Eczema was prospectively assessed by annual questionnaires until the age of 4 years. Eczema patterns included never, early (age ≤1 year only), late (age >1 year only), and persistent eczema (age ≤ and >1 year). Data were assessed using the generalized estimating equations and multinomial regression models.

RESULTS

Compared with the optimal 25-hydroxyvitamin D group, sufficient, deficient, and severely deficient groups of 25-hydroxyvitamin D level in mid-gestation were not associated with the risk of overall eczema (odds ratios [95% confidence interval]: 1.09 [0.82, 1.43], 1.04 [0.87, 1.25], and 0.94 [0.81, 1.10], p-values for trend >0.05), nor with eczema per year or eczema patterns in children up to the age of 4 years. Similarly, we observed no associations of 25-hydroxyvitamin D groups at birth with any eczema outcome.

CONCLUSION

Our results suggest that levels of 25-hydroxyvitamin D in mid-gestation and at birth are not associated with the risk of overall eczema, eczema per year, or eczema patterns among children until the age of 4 years.

Maternal folate status as a risk factor for autism spectrum disorders: a review of existing evidence

Emerging evidence from epidemiological studies supports the notion that maternal folate status regulated by dietary and genetic factors early in pregnancy may influence the risk of autism spectrum disorders (ASD). In this review, we provide an overview of what is known about the role of folate in the aetiology of neurodevelopmental disorders; summarise relevant biological, genetic and epigenetic mechanisms; and synthesise the evidence from human observational studies and randomised controlled trials that have examined the relationship between maternal folate and ASD or related traits. Much of the existing literature on this topic is subject to limitations such as potential confounding by healthy behaviours and other dietary factors, and exposure assessed within limited exposure windows. As the existing evidence is inconclusive, further research remains to be conducted in order to verify this hypothesis. Complete assessment of maternal functional folate status through the pre- and peri-conceptional periods requires biological measurement of folate, vitamin B12 and homocysteine and genetic variants involved in one-carbon metabolism and epigenetic mechanisms. In addition to more complete assessment of maternal functional folate status, careful consideration of potential confounding is warranted.

The Generation R Study: Biobank update 2015

The Generation R Study is a population-based prospective cohort study from fetal life until adulthood. The study is designed to identify early environmental and genetic causes and causal pathways leading to normal and abnormal growth, development and health from fetal life, childhood and young adulthood. In total, 9,778 mothers were enrolled in the study. Data collection in children and their parents include questionnaires, interviews, detailed physical and ultrasound examinations, behavioural observations, Magnetic Resonance Imaging and biological samples. Efforts have been conducted for collecting biological samples including blood, hair, faeces, nasal swabs, saliva and urine samples and generating genomics data on DNA, RNA and microbiome. In this paper, we give an update of the collection, processing and storage of these biological samples and available measures. Together with detailed phenotype measurements, these biological samples provide a unique resource for epidemiological studies focused on environmental exposures, genetic and genomic determinants and their interactions in relation to growth, health and development from fetal life onwards.