Folic AcidMethotrexateFolic Acid DeficiencyNeural Tube DefectsFolic Acid AntagonistsTetrahydrofolatesHomocysteineVitamin B ComplexVitamin B 12Food, FortifiedDietary SupplementsPolyglutamic AcidPreconception CareFolate Receptors, GPI-AnchoredAntirheumatic AgentsAminopterinTetrahydrofolate DehydrogenaseReduced Folate Carrier ProteinPteroylpolyglutamic AcidsHyperhomocysteinemiaAnemia, MacrocyticHematinicsVitamin B 6FormyltetrahydrofolatesTrimetrexatePregnancyAntimetabolites, AntineoplasticLeukemia L1210Arthritis, Rheumatoidgamma-Glutamyl HydrolaseVitamin B 12 DeficiencyFolic Acid TransportersLeucovorinBreadDouble-Blind MethodVitaminsPrenatal CareMethylenetetrahydrofolate Reductase (NADPH2)Drug Therapy, CombinationFolate Receptor 1FlourTreatment OutcomeDrug ResistanceDose-Response Relationship, DrugPrenatal Nutritional Physiological PhenomenaPterinsSpinal DysraphismDrug Administration ScheduleDeoxyuridine4-Aminobenzoic AcidThymidylate SynthaseAbortifacient Agents, NonsteroidalCyclophosphamideGlutamatesAdministration, OralImmunosuppressive AgentsAntineoplastic Combined Chemotherapy ProtocolsFIGLU TestPyridoxineCerealsMicronutrientsBiological AvailabilitySulfasalazineVincristineDietPrecursor Cell Lymphoblastic Leukemia-LymphomaAnencephalyNutritional RequirementsLactobacillus caseiHomocystineMethylmalonic AcidErythrocytesNutrition Policy6-MercaptopurineHydroxymethyl and Formyl TransferasesDermatologic AgentsPregnancy, EctopicMethionineRiboflavinFluorouracilBiological TransportKB CellsTime FactorsAnemia, MegaloblasticPlacebosNutritional StatusMaternal Nutritional Physiological PhenomenaCarrier ProteinsCleft PalateDoxorubicinIsoxazolesPregnancy Complications, HematologicPhosphoribosylaminoimidazolecarboxamide Formyltransferasepara-AminobenzoatesOsteosarcomaInjections, SpinalPrednisoneCytarabineVitamin B DeficiencyLeukemia, Lymphoid