Neural Tube DefectsNeural TubeAnencephalySpinal DysraphismFolic AcidSpina Bifida OccultaNeurulationSpina Bifida CysticaEncephalocelePregnancyMeningomyeloceleVitamin B ComplexPreconception CarePrenatal DiagnosisFood, FortifiedCongenital AbnormalitiesFolic Acid DeficiencyAbortion, Therapeuticalpha-FetoproteinsNeural CrestInfant, NewbornNervous SystemAir Pollution, RadioactiveAmniocentesisPrenatal CareEmbryo, MammalianAmniotic FluidDietary SupplementsMouth AbnormalitiesIrelandGene Expression Regulation, DevelopmentalCentral Nervous SystemFetal DeathChick EmbryoFlourHomocysteineVitamin B 12TailZinebPaired Box Transcription FactorsMethylenetetrahydrofolate Reductase (NADPH2)Mice, Mutant StrainsEmbryonic and Fetal DevelopmentVitamin B 12 DeficiencyBody PatterningMethylenetetrahydrofolate Dehydrogenase (NADP)NotochordIn Situ HybridizationVitaminsFetal DiseasesPregnancy in DiabeticsEmbryonic DevelopmentManebPregnancy ComplicationsFormate-Tetrahydrofolate LigaseGestational AgeThymidine MonophosphateDeanolTeratogensPollen TubeMorphogenesisCase-Control StudiesFolate Receptor 1Maternal ExposurePrenatal Nutritional Physiological PhenomenaMutationAbnormalities, Drug-InducedAbortion, InducedTetrahydrofolatesAbnormalities, MultipleCleft LipTranscobalaminsBreadPhenotypeHeart Defects, CongenitalTranscription FactorsCraniofacial AbnormalitiesHomeodomain ProteinsPregnancy Trimester, SecondPregnancy Trimester, FirstThiocholineMeningoceleFolate Receptors, GPI-AnchoredPrevalenceRisk FactorsQuailEstriolHydrocephalusDown SyndromeMaternal Nutritional Physiological PhenomenaCerebral AqueductRiskMice, Neurologic MutantsCleft PalateTrisomyHomozygote