Neural Tube DefectsNeural TubeAnencephalySpinal DysraphismFolic AcidSpina Bifida OccultaNeurulationSpina Bifida CysticaEncephalocelePregnancyMeningomyeloceleVitamin B ComplexPreconception CarePrenatal DiagnosisFood, FortifiedCongenital AbnormalitiesFolic Acid DeficiencyAbortion, Therapeuticalpha-FetoproteinsInfant, NewbornNeural CrestNervous SystemPrenatal CareAir Pollution, RadioactiveAmniocentesisDietary SupplementsEmbryo, MammalianAmniotic FluidIrelandMouth AbnormalitiesGene Expression Regulation, DevelopmentalCentral Nervous SystemFetal DeathFlourChick EmbryoHomocysteineVitamin B 12TailZinebPaired Box Transcription FactorsMethylenetetrahydrofolate Reductase (NADPH2)Mice, Mutant StrainsEmbryonic and Fetal DevelopmentVitamin B 12 DeficiencyBody PatterningMethylenetetrahydrofolate Dehydrogenase (NADP)NotochordVitaminsIn Situ HybridizationFetal DiseasesPregnancy in DiabeticsPregnancy ComplicationsEmbryonic DevelopmentManebFormate-Tetrahydrofolate LigaseGestational AgeRisk FactorsThymidine MonophosphateCase-Control StudiesDeanolTeratogensMorphogenesisPollen TubeMutationMaternal ExposurePrenatal Nutritional Physiological PhenomenaFolate Receptor 1Abnormalities, Drug-InducedAbortion, InducedPrevalenceTetrahydrofolatesAbnormalities, MultipleCleft LipPhenotypeBreadHeart Defects, CongenitalTranscobalaminsTranscription FactorsPrimary PreventionRiskCraniofacial AbnormalitiesHomeodomain ProteinsPregnancy Trimester, SecondPregnancy Trimester, FirstThiocholineMeningoceleFolate Receptors, GPI-AnchoredEstriolHydrocephalusQuailMaternal Nutritional Physiological PhenomenaDown SyndromeCleft PalateCerebral AqueductMice, Neurologic MutantsHomozygoteTrisomyCalifornia