Neural Tube DefectsNeural TubeAnencephalySpinal DysraphismFolic AcidSpina Bifida OccultaNeurulationSpina Bifida CysticaEncephalocelePregnancyMeningomyeloceleVitamin B ComplexPreconception CarePrenatal DiagnosisIncidenceFood, FortifiedCongenital AbnormalitiesFolic Acid DeficiencyAbortion, TherapeuticInfant, Newbornalpha-FetoproteinsNeural CrestNervous SystemAir Pollution, RadioactiveAmniocentesisPrenatal CareEmbryo, MammalianDietary SupplementsAmniotic FluidIrelandMouth AbnormalitiesGene Expression Regulation, DevelopmentalFetal DeathCentral Nervous SystemFlourChick EmbryoHomocysteineVitamin B 12TailZinebPaired Box Transcription FactorsMethylenetetrahydrofolate Reductase (NADPH2)Mice, Mutant StrainsEmbryonic and Fetal DevelopmentVitamin B 12 DeficiencyBody PatterningMethylenetetrahydrofolate Dehydrogenase (NADP)NotochordIn Situ HybridizationVitaminsFetal DiseasesPregnancy in DiabeticsRisk FactorsPregnancy ComplicationsEmbryonic DevelopmentManebGestational AgeFormate-Tetrahydrofolate LigaseCase-Control StudiesThymidine MonophosphateTeratogensDeanolMutationPollen TubeMorphogenesisMaternal ExposureFolate Receptor 1Prenatal Nutritional Physiological PhenomenaPrevalenceAbortion, InducedAbnormalities, Drug-InducedAbnormalities, MultiplePhenotypeTetrahydrofolatesRiskCleft LipHeart Defects, CongenitalBreadTranscobalaminsTranscription FactorsCraniofacial AbnormalitiesHomeodomain ProteinsPregnancy Trimester, SecondPregnancy Trimester, FirstThiocholineMeningoceleFolate Receptors, GPI-AnchoredTime FactorsHydrocephalusDown SyndromeEstriolQuailCleft PalateMaternal Nutritional Physiological PhenomenaCaliforniaHomozygoteCerebral AqueductTrisomyMice, Neurologic MutantsPregnancy Outcome