Czeizel AE, Dudas I, Metneki J Pregnancy outcomes in a randomised controlled trial of periconceptional multivitamin supplementation. Final report. Arch Gynecol Obstet. 1994;255(3):131-9. doi: 10.1007/BF02390940.
Czeizel AE, Susanszky E Diet intake and vitamin supplement use of Hungarian women during the preconceptional period. Int J Vitam Nutr Res. 1994;64(4):300-5.
Czeizel AE, Tomcsik M Acute toxicity of folic acid in pregnant women. Teratology. 1999 Jul;60(1):3-4. doi: 10.1002/(SICI)1096-9926(199907)60:13.0.CO;2-4. No abstract available.
Dalery K, Lussier-Cacan S, Selhub J, Davignon J, Latour Y, Genest J Jr Homocysteine and coronary artery disease in French Canadian subjects: relation with vitamins B12, B6, pyridoxal phosphate, and folate. Am J Cardiol. 1995 Jun 1;75(16):1107-11. doi: 10.1016/s0002-9149(99)80739-5.
Ericson A, Kallen B, Aberg A Use of multivitamins and folic acid in early pregnancy and multiple births in Sweden. Twin Res. 2001 Apr;4(2):63-6. doi: 10.1375/1369052012155.
Furness DL, Fenech MF, Khong YT, Romero R, Dekker GA One-carbon metabolism enzyme polymorphisms and uteroplacental insufficiency. Am J Obstet Gynecol. 2008 Sep;199(3):276.e1-8. doi: 10.1016/j.ajog.2008.06.020.
Guven MA, Coskun A, Ertas IE, Aral M, Zencirci B, Oksuz H Association of maternal serum CRP, IL-6, TNF-alpha, homocysteine, folic acid and vitamin B12 levels with the severity of preeclampsia and fetal birth weight. Hypertens Pregnancy. 2009 May;28(2):190-200. doi: 10.1080/10641950802601179.
Hustad S, Midttun O, Schneede J, Vollset SE, Grotmol T, Ueland PM The methylenetetrahydrofolate reductase 677C-->T polymorphism as a modulator of a B vitamin network with major effects on homocysteine metabolism. Am J Hum Genet. 2007 May;80(5):846-55. doi: 10.1086/513520. Epub 2007 Mar 13.
Kirke PN, Daly LE, Elwood JH A randomised trial of low dose folic acid to prevent neural tube defects. The Irish Vitamin Study Group. Arch Dis Child. 1992 Dec;67(12):1442-6. doi: 10.1136/adc.67.12.1442.
Larsson SC, Giovannucci E, Wolk A Folate and risk of breast cancer: a meta-analysis. J Natl Cancer Inst. 2007 Jan 3;99(1):64-76. doi: 10.1093/jnci/djk006.
Shakur YA, Garriguet D, Corey P, O'Connor DL Folic acid fortification above mandated levels results in a low prevalence of folate inadequacy among Canadians. Am J Clin Nutr. 2010 Oct;92(4):818-25. doi: 10.3945/ajcn.2010.29696. Epub 2010 Aug 25.
Shane B, Stokstad EL Vitamin B12-folate interrelationships. Annu Rev Nutr. 1985;5:115-41. doi: 10.1146/annurev.nu.05.070185.000555.
Stevens VL, McCullough ML, Sun J, Gapstur SM Folate and other one-carbon metabolism-related nutrients and risk of postmenopausal breast cancer in the Cancer Prevention Study II Nutrition Cohort. Am J Clin Nutr. 2010 Jun;91(6):1708-15. doi: 10.3945/ajcn.2009.28553. Epub 2010 Apr 21.
Stover PJ Physiology of folate and vitamin B12 in health and disease. Nutr Rev. 2004 Jun;62(6 Pt 2):S3-12; discussion S13. doi: 10.1111/j.1753-4887.2004.tb00070.x.
Wilson RD; GENETICS COMMITTEE; MOTHERISK RETIRED: Pre-conceptional vitamin/folic acid supplementation 2007: the use of folic acid in combination with a multivitamin supplement for the prevention of neural tube defects and other congenital anomalies. J Obstet Gynaecol Can. 2007 Dec;29(12):1003-1013. doi: 10.1016/S1701-2163(16)32685-8. Erratum In: J Obstet Gynaecol Can. 2008 Mar;30(3):193. Goh, Ingrid [corrected to Goh, Y Ingrid]. English, French.
Interventional studies are often prospective and are specifically tailored to evaluate direct impacts of treatment or preventive measures on disease.
Observational studies are often retrospective and are used to assess potential causation in exposure-outcome relationships and therefore influence preventive methods.
Expanded access is a means by which manufacturers make investigational new drugs available, under certain circumstances, to treat a patient(s) with a serious disease or condition who cannot participate in a controlled clinical trial.
Clinical trials are conducted in a series of steps, called phases - each phase is designed to answer a separate research question.
Phase 1: Researchers test a new drug or treatment in a small group of people for the first time to evaluate its safety, determine a safe dosage range, and identify side effects.
Phase 2: The drug or treatment is given to a larger group of people to see if it is effective and to further evaluate its safety.
Phase 3: The drug or treatment is given to large groups of people to confirm its effectiveness, monitor side effects, compare it to commonly used treatments, and collect information that will allow the drug or treatment to be used safely.
Phase 4: Studies are done after the drug or treatment has been marketed to gather information on the drug's effect in various populations and any side effects associated with long-term use.