Neural Tube DefectsNeural TubeAnencephalySpinal DysraphismFolic AcidSpina Bifida OccultaNeurulationSpina Bifida CysticaEncephalocelePregnancyMeningomyeloceleVitamin B ComplexPreconception CarePrenatal DiagnosisFood, FortifiedCongenital AbnormalitiesFolic Acid DeficiencyAbortion, Therapeuticalpha-FetoproteinsInfant, NewbornNeural CrestNervous SystemAir Pollution, RadioactiveAmniocentesisPrenatal CareEmbryo, MammalianAmniotic FluidDietary SupplementsMouth AbnormalitiesIrelandGene Expression Regulation, DevelopmentalCentral Nervous SystemFetal DeathChick EmbryoFlourHomocysteineVitamin B 12TailZinebPaired Box Transcription FactorsMethylenetetrahydrofolate Reductase (NADPH2)Mice, Mutant StrainsVitamin B 12 DeficiencyEmbryonic and Fetal DevelopmentBody PatterningMethylenetetrahydrofolate Dehydrogenase (NADP)In Situ HybridizationNotochordVitaminsFetal DiseasesPregnancy in DiabeticsEmbryonic DevelopmentPregnancy ComplicationsManebCase-Control StudiesFormate-Tetrahydrofolate LigaseGestational AgeThymidine MonophosphateTeratogensDeanolMutationMorphogenesisPollen TubeMaternal ExposureFolate Receptor 1Prenatal Nutritional Physiological PhenomenaAbnormalities, Drug-InducedAbnormalities, MultiplePhenotypeAbortion, InducedCleft LipTetrahydrofolatesRisk FactorsHeart Defects, CongenitalTranscobalaminsTranscription FactorsBreadCraniofacial AbnormalitiesHomeodomain ProteinsPregnancy Trimester, SecondPrevalencePregnancy Trimester, FirstThiocholineMeningoceleCleft PalateFolate Receptors, GPI-AnchoredRiskHydrocephalusDown SyndromeQuailEstriolMaternal Nutritional Physiological PhenomenaHomozygoteMice, Neurologic MutantsCerebral AqueductTrisomy