First Trimester Use of Buprenorphine or Methadone and the Risk of Congenital Malformations.

Importance: Use of buprenorphine or methadone to treat opioid use disorder is recommended in pregnancy; however, their teratogenic potential is largely unknown. Objective: To compare the risk of congenital malformations following in utero exposure to buprenorphine vs methadone. Design, Setting, and Participants: This population-based cohort study used health care utilization data from publicly insured Medicaid beneficiaries in the US from 2000 to 2018. A total of 13 360 pregnancies with enrollment from 90 days prior to pregnancy start through 1 month after delivery and first trimester use of buprenorphine or methadone were included and linked to infants. Data were analyzed from July to December 2022. Exposure: A pharmacy dispensing of buprenorphine or a code for administration of methadone in the first trimester. Main Outcomes and Measures: Primary outcomes included major malformations overall and malformations previously associated with opioids (any cardiac malformations, ventricular septal defect, secundum atrial septal defect/nonprematurity-related patent foramen ovale, neural tube defects, clubfoot, and oral clefts). Secondary outcomes included other organ system-specific malformations. Risk differences and risk ratios (RRs) were estimated comparing buprenorphine with methadone, adjusting for confounders with propensity score overlap weights. Results: The cohort included 9514 pregnancies with first-trimester buprenorphine exposure (mean [SD] maternal age, 28.4 [4.6] years) and 3846 with methadone exposure (mean [SD] maternal age, 28.8 [4.7] years). The risk of malformations overall was 50.9 (95% CI, 46.5-55.3) per 1000 pregnancies for buprenorphine and 60.6 (95% CI, 53.0-68.1) per 1000 pregnancies for methadone. After confounding adjustment, buprenorphine was associated with a lower risk of malformations compared with methadone (RR, 0.82; 95% CI, 0.69-0.97). Risk was lower with buprenorphine for cardiac malformations (RR, 0.63; 95% CI, 0.47-0.85), including both ventricular septal defect (RR, 0.62; 95% CI, 0.39-0.98) and secundum atrial septal defect/nonprematurity-related patent foramen ovale (RR, 0.54; 95% CI, 0.30-0.97), oral clefts (RR, 0.65; 95% CI, 0.35-1.19), and clubfoot (RR, 0.55; 95% CI, 0.32-0.94). Results for neural tube defects were uncertain given low event counts. In secondary analyses, buprenorphine was associated with a decreased risk of central nervous system, urinary, and limb malformations but a greater risk of gastrointestinal malformations compared with methadone. These findings were consistent in sensitivity and bias analyses. Conclusions and Relevance: In this cohort study, the risk of most malformations previously associated with opioid exposure was lower in buprenorphine-exposed infants compared with methadone-exposed infants, independent of measured confounders. Malformation risk is one factor that informs the individualized patient decision regarding medications for opioid use disorder in pregnancy.

Dolutegravir-induced neural tube defects in mice are folate responsive.

OBJECTIVES: In 2018, the Botswana Tsepamo Study reported a nine-fold increased risk of neural tube defects in infants whose mothers were treated with dolutegravir (DTG) from the time of conception. As maternal folate supplementation and status is a well known modifier of neural tube defect (NTD) risk, we sought to evaluate birth outcomes in mice fed normal and low folic acid diets treated with DTG during pregnancy. DESIGN: DTG was evaluated for developmental toxicity using pregnant mice fed normal or low folic acid diet. METHODS: CD-1 mice were provided diet with normal (3 mg/kg) or low (0.3 mg/kg) folic acid. They were treated with water, a human therapeutic-equivalent dose, or supratherapeutic dose of DTG from mouse embryonic day E6.5 to E12.5. Pregnant dams were sacrificed at term (E18.5) and fetuses were inspected for gross, internal, and skeletal defects. RESULTS: Fetuses with exencephaly, an NTD, were present in both therapeutic human equivalent and supratherapeutic exposures in dams fed low folic acid diet. Cleft palates were also found under both folate conditions. CONCLUSIONS: Recommended dietary folic acid levels during mouse pregnancy ameliorate developmental defects that arise from DTG exposure. Since low folate status in mice exposed to DTG increases the risk for NTDs, it is possible that DTG exposures in people living with HIV with low folate status during pregnancy may explain, at least in part, the elevated NTD risk signal observed in Botswana. Based on these results, future studies should consider folate status as a modifier for DTG-associated NTD risk.

Descriptive epidemiology of external structural birth defects in Enugu State, Nigeria.

Objectives: To determine the birth prevalence, trend, and characteristics of external structural birth defects occurrence in Enugu Metropolis, Nigeria. Design: Cross-sectional study involving review of delivery records. Setting: The study was conducted at three tertiary hospitals, one public and two missionary, in Enugu Metropolis. Participants: Mothers and their babies delivered between 1 January 2009 and 31 December 2016 in the study facilities. Main outcome measures: Birth prevalence of defects presented as frequency/10,000 births. Other descriptive variables are presented as frequencies and percentages. Results: There were 21530 births with 133 birth defects (birth prevalence: 61.8/10,000 births) and 1176 stillbirths (stillbirth rate: 54.6/1000 births). The frequencies and birth prevalence (/10,000 births) of recorded defects were: Limb deformities 60(27.9), Neural tube defects (NTDs): 36(16.7), Urogenital system defects: 12(5.6), Gastrointestinal system defects 10(4.6) and Orofacial clefts 4(1.9). Birth defects occurrence showed a rising trend from 2009 to 2016. The mean (SD) age of mothers whose babies had Birth defects was 29.1(4.7) years. Only 62(46.6%) of 133 antenatal clinic folders of these women were traceable for further review. Eighteen (29.0%) had febrile illness in early pregnancy, 9(14.5%) had Malaria, 17(27.4%) had <4 antenatal clinic attendance, 7(11.3%) did not take folic acid and 6(9.7%) took herbal medications during pregnancy. Conclusions: Birth defects occurrence showed a rising trend with limb deformities and NTDs having the highest prevalence. Record keeping was poor at the facilities. Birth defects preventive interventions like folic acid supplementation for women-of-childbearing age should be promoted in Enugu Metropolis. Funding: This work was supported by the non-communicable disease Minigrant from the Task Force for Global Health, Decatur, Georgia, USA (TPN-FE-NCD-C2-IFO-9).

Intrathecal baclofen therapy for severe spasticity in an adult with tethered cord syndrome: a case report.

BACKGROUND: Patients with tethered cord syndrome often suffer severe spasticity. To the best of our knowledge, intrathecal baclofen (ITB) therapy in a patient with tethered cord syndrome has not been reported previously. We describe a case in which ITB therapy was useful for treating severe spasticity in an adult with tethered cord syndrome. CASE PRESENTATION: We present the case of a 50-year-old Japanese woman with tethered cord syndrome and related conditions suffering from severe spasticity and pain in the lower limbs. She was born with a lumbosacral myelomeningocele, which was closed in the neonatal period. For 4-5 years before this presentation, spasticity in the lower limbs had been exacerbated without any obvious cause. She received rehabilitation and pharmacotherapy from a local doctor, but symptoms were unimproved, and her previous doctor referred her to this department. A test with 50 µg of intrathecally delivered baclofen showed total relief of spasticity and pain, so a pump was implanted for continuous baclofen delivery. During 24 months of follow-up, spasticity has remained under excellent control with baclofen at 38.5-41.0 µg/day. CONCLUSIONS: ITB therapy proved extremely effective in this adult with severe spasticity from tethered code syndrome.

Perspective: Weekly Iron and Folic Acid Supplementation (WIFAS): A Critical Review and Rationale for Inclusion in the Essential Medicines List to Accelerate Anemia and Neural Tube Defects Reduction.

Weekly iron and folic acid supplementation (WIFAS) is among the 8 key effective actions for improving adolescent nutrition included by the WHO in the 2018 guidelines. However, at present WIFAS in the WHO-recommended formulation is not included in the Model Essential Medicines List (MEML), limiting the potential for countries to import, produce, and prioritize this formulation as part of their national supply management and procurement plans for medicines. The WHO WIFAS guideline presents evidence that the formulation reduces anemia, but not that folic acid reduces neural tube defects (NTDs), because sufficient evidence was unavailable at the time of the last review. Recently, a 3-arm, parallel-group, randomized, double-blind, placebo-controlled folic acid efficacy trial on WIFAS was conducted to address this evidence gap. The study population included 331 women (18-45 y old), randomly assigned to 3 treatment groups, including a supplement with 60 mg Fe as ferrous fumarate and either 0 mg, 0.4 mg, or 2.8 mg of folic acid, to be consumed once weekly for 16 wk, followed by a 4-wk washout period. In this article we critically review how the outcomes of this folic acid efficacy trial, and how the evidence generated, could potentially be used to inform WHO WIFAS guidelines for the potential inclusion of this formulation on the MEML, and how this, in turn, may affect product availability. If the new evidence on weekly folic acid is assessed as adequately reducing the risk of NTDs, a guideline revision could be warranted and WIFAS could be presented to the MEML for the dual benefits of anemia reduction and NTD prevention. This inclusion could enable acceleration of implementing policies and programs to contribute to global anemia and NTD reduction efforts.

A propensity-matched study of the association between optimal folic acid supplementation and birth defects in Shaanxi province, Northwestern China.

The association between folic acid supplementation and birth defects other than neural tube defects remains unclear. We utilized data from a large population-based survey to examine the association between folic acid supplementation and birth defects in Northwestern China. A total of 29,204 women with infants born between 2010 and 2013 were surveyed in Shaanxi province, Northwestern China, using a stratified multistage sampling method. Propensity scores were used to match 9,293 women with optimal folic acid supplementation with 9,293 women with nonoptimal folic acid supplementation, and the effects of optimal folic acid supplementation on birth defects were assessed by a conditional logistic regression model. After propensity score matching, the overall birth defect rate, cardiovascular system defect rate and nervous system defect rate for the women with optimal folic acid supplementation were lower than those for the women with nonoptimal folic acid supplementation (overall birth defects: OR = 0.71, 95% CI = 0.57-0.89, P = 0.003; cardiovascular system defects: OR = 0.65, 95% CI = 0.44-0.96, P = 0.032; nervous system defects: OR = 0.13, 95% CI = 0.02-0.99, P = 0.049). Optimal folic acid supplementation was associated with a decreased prevalence of birth defects, especially in the cardiovascular system and nervous system. Our findings have important implications for birth defect intervention with folic acid supplementation for countries with a high prevalence of birth defects, such as China.

Quantitation of 5-methyltetraydrofolic acid in plasma for determination of folate status and clinical studies by stable isotope dilution assays.

Folates play a key role in the prevention of neural tube defects in newborns. Thus, it is important to reliably determine the bioavailability of folates from various foods. Accurate analytical methods are essential for quantifying blood-folates, especially in human studies. Here, we present the development and validation of a sensitive method using stable isotope dilution liquid chromatography coupled with mass spectrometry for determining various folates in plasma. Moreover, this study reports the applicability of the developed method to a human pilot study using strawberries as a test food. Validation of the assay revealed the precision, sensitivity, and accuracy of the method in determining the predominant 5-methyltetrahydrofolate in plasma. This method was also applicable for the screening of individual folate status using finger prick blood and for monitoring the post-absorptive plasma-concentration curve. Moreover, the human study revealed a high recovery of strawberry folates with a calculated relative bioavailability of 96.2%. Thus, the developed method enables prospective bioavailability studies. This work also confirmed, via human studies, that strawberries are a rich and natural source of folates that are available for human metabolism.

Aberrant methylation of Pax3 gene and neural tube defects in association with exposure to polycyclic aromatic hydrocarbons.

BACKGROUND: Neural tube defects (NTDs) are common and severe congenital malformations. Pax3 is an essential gene for neural tube closure in mice but it is unknown whether altered expression or methylation of PAX3 contributes to human NTDs. We examined the potential role of hypermethylation of Pax3 in the development of NTDs by analyzing human NTD cases and a mouse model in which NTDs were induced by benzo[a]pyrene (BaP), a widely studied polycyclic aromatic hydrocarbon (PAH). METHODS: We extracted methylation information of PAX3 in neural tissues from array data of ten NTD cases and eight non-malformed controls. A validation study was then performed in a larger independent population comprising 73 NTD cases and 29 controls. Finally, we examined methylation patterns and expression of Pax3 in neural tissues from mouse embryos of dams exposed to BaP or BaP and vitamin E. RESULTS: Seven CpG sites in PAX3 were hypermethylated in NTD fetuses as compared to controls in the array data. In the validation phase, significantly higher methylation levels in the body region of PAX3 were observed in NTD cases than in controls (P = 0.003). And mean methylation intensity in the body region of PAX3 in fetal neural tissues was positively correlated with median concentrations of PAH in maternal serum. In the mouse model, BaP-induced NTDs were associated with hypermethylation of specific CpG sites within both the promoter and body region of Pax3. Supplementation with vitamin E via chow decreased the rate of NTDs, partly recovered the repressed total antioxidant capacity in mouse embryos exposed to BaP, and this was accompanied by the normalization of Pax3 methylation level and gene expression. CONCLUSION: Hypermethylation of Pax3 may play a role in the development of NTDs; DNA methylation aberration may be caused by exposure to BaP, with possible involvement of oxidative stress.

The effect of folic acid deficiency on FGF pathway via Brachyury regulation in neural tube defects.

Folate deficiency in early development leads to disturbance in multiple processes, including neurogenesis during which fibroblast growth factor (FGF) pathway is one of the crucial pathways. Whether folic acid (FA) directly affects FGF pathways to influence neurodevelopment and the possible mechanism remains unclear. In this study, we presented evidence that in human FA-insufficient encephalocele, the FGF pathway was interfered. Furthermore, in Brachyury knockout mice devoid of such T-box transcription factors regulating embryonic neuromesodermal bipotency and a key component of FGF pathway, change in expression of Brachyury downstream targets, activator Fgf8 and suppressor dual specificity phosphatase 6 was detected, along with the reduction in expression of other key FGF pathway genes. By using a FA-deficient cell model, we further demonstrated that decrease in Brachyury expression was through alteration in hypermethylation at the Brachyury promoter region under FA deficiency conditions, and suppression of Brachyury promoted the inactivation of the FGF pathway. Correspondingly, FA supplementation partially reverses the effects seen in FA-deficient embryoid bodies. Lastly, in mice with maternal folate-deficient diets, aberrant FGF pathway activity was found in fetal brain dysplasia. Taken together, our findings highlight the effect of FA on FGF pathways during neurogenesis, and the mechanism may be due to the low expression of Brachyury gene via hypermethylation under FA-insufficient conditions.-Chang, S., Lu, X., Wang, S., Wang, Z., Huo, J., Huang, J., Shangguan, S., Li, S., Zou, J., Bao, Y., Guo, J., Wang, F., Niu, B., Zhang, T., Qiu, Z., Wu, J., Wang, L. The effect of folic acid deficiency on FGF pathway via Brachyury regulation in neural tube defects.

Key apoptotic genes APAF1 and CASP9 implicated in recurrent folate-resistant neural tube defects.

Neural tube defects (NTDs) remain one of the most serious birth defects, and although genes in several pathways have been implicated as risk factors for neural tube defects via knockout mouse models, very few molecular causes in humans have been identified. Whole exome sequencing identified deleterious variants in key apoptotic genes in two families with recurrent neural tube defects. Functional studies in fibroblasts indicate that these variants are loss-of-function, as apoptosis is significantly reduced. This is the first report of variants in apoptotic genes contributing to neural tube defect risk in humans.

Ethical stumbling blocks in uncovering folate deficiency as a preventable cause of spina bifida.

The year 2016 witnessed the anniversaries of several key events related to the prevention of neural tube defects (NTD) with folate supplementation. However, the road leading up to this achievement was full of stumbling blocks, both in terms of research ethics and researcher ethics. First, the decisions of ethics review boards differed with respect to allowing placebo groups in folate trials, thus reducing the level of evidence obtained from the earliest studies. Second, statisticians insisted on analysing the outcome of a trial by intention-to-treat - which turned out to be non-significant - rather than by treatment received, which was statistically significant. Third, the recognition of positive results was stymied by the reluctance of some researchers to recognise and quote others' contributions. All this needlessly delayed the recognition of the NTD-preventive effects of folate by a decade. The story of the prevention of NTD thus offers insights into research inadequacies that have the potential to impede the advance of medical science, with the ethical aspects having the most immediate impact. Efficient ethics review boards play a major role worldwide and if they play safe, they may risk disallowing high-quality studies of great public health import.

Abnormal O-GlcNAcylation of Pax3 Occurring from Hyperglycemia-Induced Neural Tube Defects Is Ameliorated by Carnosine But Not Folic Acid in Chicken Embryos.

Neural tube defects (NTDs) are among the most common of the embryonic abnormalities associated with hyperglycemic gestation. In this study, the molecular mechanisms of embryonic neurogenesis influenced by hyperglycemia was investigated using chicken embryo models. High-concentration glucose was administered into chicken eggs and resulted in increased plasma and brain tissue glucose, and suppressed expression of glucose transporters (GLUTs). The rate of NTD positively correlated with hyperglycemia. Furthermore, abnormally increased O-GlcNAcylation, a nutritionally responsive modification, of the key neural tube marker Pax3 protein led to the loss of this protein. This loss was not observed in a folate-deficiency NTD induced by methotrexate. Carnosine, an endogenous dipeptide, showed significant recovery effects on neural tube development. In contrast, folic acid, a well-known periconceptional agent, surprisingly showed relatively minimal effect. Higher expression levels of the Pax3 protein were found in the carnosine-treated groups, while lower expression levels were found in folic acid groups. Furthermore, the abnormal O-GlcNAcylation of the Pax3 protein was restored by carnosine. These results suggest new insights into using endogenous nutrients for the protection of embryonic neurodevelopment affected by diabetes gestation. The abnormal excessive O-GlcNAcylation of Pax3 may be responsible for the neural tube defects associated with hyperglycemia.

The association and significance of H3K27me3 and a folate metabolic gene ACat2 in neural tube defects.

AIM: To study the association between the expression of H3K27me3 and ACat2 (a folate metabolic protein), in order to elucidate the protective mechanism of folic acid (FA) in neural tube defects (NTDs). METHODS: Eighteen female SD rats were randomly divided into normal, NTD and FA group. NTD group was induced by all-trans retinoic acid (ATRA) at E10d. FA group was fed with FA supplementation since 2 weeks before pregnancy, followed by ATRA induction. At E15d, FA level in the embryonic neural tube was determined by ELISA. Neural stem cells (NSCs) were isolated. Cell proliferation was compared by CCK-8 assay. The differentiation potency was assessed by immunocytochemical staining. H3K27me3 expression was measured by immunofluorescence method and Western blot. ACat2 mRNA expression was detected by qRT-PCR. RESULTS: Cultured NSCs formed numerous Nestin-positive neurospheres. After 5 days, they differentiated into NSE-positive neurons and GFAP-positive astrocytes. When compared with controls, the FA level in NTD group was significantly lower, the ability of cell proliferation and differentiation was significantly reduced, H3K27me3 expression was increased, and ACat2 mRNA expression was decreased (P <0.05). The intervention of FA notably reversed these changes (P <0.05). H3K27me3 expression was negatively correlated with the FA level (rs = -0.908, P <0.01) and ACat2 level (rs = -0.879, P <0.01) in the neural tube. CONCLUSION: The increased H3K27me3 expression might cause a disorder of folate metabolic pathway by silencing ACat2 expression, leading to reduced proliferation and differentiation of NSCs, and ultimately the occurrence of NTD. FA supplementation may reverse this process.

Food Additives Permitted for Direct Addition to Food for Human Consumption; Folic Acid. Final rule.

The Food and Drug Administration (FDA or we) is amending the food additive regulations to provide for the safe use of folic acid in corn masa flour. We are taking this action in response to a food additive petition filed jointly by Gruma Corporation, Spina Bifida Association, March of Dimes Foundation, American Academy of Pediatrics, Royal DSM N.V., and National Council of La Raza.

[Periconceptional folic acid prophylaxis and neural tube defects]. / Perikonceptionel folinsyreprofylakse og neuralrørsdefekter.

Neural tube defects (NTD) affect 60-70 pregnancies each year in Denmark. Folic acid (FA) intake can reduce the risk of NTD in pregnancy. The Danish Health and Medicines Authority recom­mends Danish women to take 0.4 mg of FA daily periconcep­tionally. Several studies have found low compliance regarding FA supplementation. In more than 70 countries around the world FA fortification of food products has been introduced and in USA and Canada this has lead to a decrease in NTD. FA fortification has not yet been introduced in Denmark. A revision of national Danish recommendations is needed.

Melatonin prevents neural tube defects in the offspring of diabetic pregnancy.

Melatonin, an endogenous neurohormone secreted by the pineal gland, has a variety of physiological functions and neuroprotective effects. However, its protective role on the neural tube defects (NTDs) was not very clear. The aim of this study was to investigate the effects of melatonin on the incidence of NTDs (including anencephaly, encephalocele, and spina bifida) of offspring from diabetic pregnant mice as well as its underlying mechanisms. Pregnant mice were given 10 mg/kg melatonin by daily i.p. injection from embryonic day (E) 0.5 until being killed on E11.5. Here, we showed that melatonin decreased the NTDs (especially exencephaly) rate of embryos exposed to maternal diabetes. Melatonin stimulated proliferation of neural stem cells (NSCs) under hyperglycemic condition through the extracellular regulated protein kinases (ERK) pathway. Furthermore, as a direct free radical scavenger, melatonin decreased apoptosis of NSCs exposed to hyperglycemia. In the light of these findings, it suggests that melatonin supplementation may play an important role in the prevention of neural malformations in diabetic pregnancy.

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

BACKGROUND: Folic acid prevents neural tube closure defects (NTDs), but the causal metabolic pathways have not been established. Serine hydroxymethyltransferase 1 (SHMT1) is an essential scaffold protein in folate-dependent de novo thymidylate synthesis in the nucleus. SHMT1-deficient mice provide a model to investigate folic acid-responsive NTDs wherein disruption of de novo thymidylate synthesis impairs neural tube closure. OBJECTIVE: We examined the effects of maternal supplementation with the pyrimidine nucleosides uridine, thymidine, or deoxyuridine with and without folate deficiency on NTD incidence in the Shmt1 mouse model. DESIGN: Shmt1(+/+) and Shmt1(-/-) female mice fed folate-replete or folate-deficient diets and supplemented with uridine, thymidine, or deoxyuridine were bred, and litters (n = 10-23 per group) were examined for the presence of NTDs. Biomarkers of impaired folate status and metabolism were measured, including plasma nucleosides, hepatic uracil content, maternal plasma folate concentrations, and incorporation of nucleoside precursors into DNA. RESULTS: Shmt1(+/-) and Shmt1(-/-) embryos from dams fed the folate-deficient diet were susceptible to NTDs. No NTDs were observed in litters from dams fed the folate-deficient diet supplemented with deoxyuridine. Surprisingly, uridine supplementation increased NTD incidence, independent of embryo genotype and dietary folic acid. These dietary nucleosides did not affect maternal hepatic uracil accumulation in DNA but did affect plasma folate concentrations. CONCLUSIONS: Maternal deoxyuridine supplementation prevented NTDs in dams fed the folate-deficient diet, whereas maternal uridine supplementation increased NTD incidence, independent of folate and embryo genotype. These findings provide new insights into the metabolic impairments and mechanisms of folate-responsive NTDs resulting from decreased Shmt1 expression.

[Periconceptional folic acid prophylaxis and neural tube defects]. / Perikonceptionel folinsyreprofylakse og neuralrørsdefekter.

Neural tube defects (NTD) affect 60-70 pregnancies each year in Denmark. Folic acid (FA) intake can reduce the risk of NTD in pregnancy. The Danish Health and Medicines Authority recommends Danish women to take 0.4 mg of FA daily periconceptionally. Several studies have found low compliance regarding FA supplementation. In more than 70 countries around the world FA fortification of food products has been introduced and in USA and Canada this has lead to a decrease in NTD. FA fortification has not yet been introduced in Denmark. A revision of national Danish recommendations is needed.

High dose of maternal folic acid supplementation is associated to infant asthma.

Maternal folic acid supplementation had a positive effect on preventing neural tube defects (NTDs), but its effects in infant asthma remained unclear. A hospital-based case-control study was conducted with outpatients between March 2010 and March 2011 including 150 onset infant asthma cases and 212 controls, together with a meta-analysis involving 14,438 participants, was performed. The association between maternal folic acid supplementation and the risk of infant asthma was not significant either in the meta-analysis (OR = 1.06, 95% CI =0.99-1.14) or in the case-control study (OR = 0.72, 95% CI =0.37-1.39). However, quantitative analysis of the supplementation dose demonstrated that the risk of infant asthma significantly increased for the infants whose mother were with high-dose supplementation (>72,000 µg•d; OR = 3.16, 95% CI =1.15-8.71) after adjusting for confounding factors in the case-control study. Meanwhile, the risk of infant asthma significantly decreased for the infants whose mother were with low-dose supplementation (<36,000 µg•d; OR = 0.36, 95% CI =0.17-0.77). A high dose of folic acid supplementation for mother during pregnancy was associated with an increased risk of infant asthma, whereas supplementation with a relatively low-dose was associated with a decreased risk of infant asthma. These findings should be further investigated in a large population.