References
- Ceylaner G, Ceylaner S, Günyeli I, et al. Evaluation of 2407 fetuses in a Turkish population. Prenat Diagn 2007;9:800–7
- Barua S, Kuizon S, Junaid MA. Folic acid supplementation in pregnancy and implications in health and disease. J Biomed Sci 2014;21:77. doi:10.1186/s12929-014-0077-z
- Elwood JM, Little J, Elwood JH. Epidemiology and control of neural tube defects. 1st ed. Oxford: Oxford University Press; 1992:242–56
- Hibbard BM. The role of folic acid in pregnancy. J Obstet Gynaecol Br Commonw 1964;71:529–42
- Werler MM, Shapiro S, Mitchell AA. Periconceptional folic acid exposure and risk of occurrent neural tube defects. JAMA 1993;269:1257–61
- Czeizel AE, Dudás I. Prevention of the first occurrence of neural-tube defects by periconceptional vitamin supplementation. N Engl J Med 1992;327:1832–5
- Holick MF, Binkley NC, Bischoff-Ferrari HA, et al. Evaluation, treatment, and prevention of vitamin D deficiency: an Endocrine Society Clinical Practice Guideline. J Clin Endocrinol Metab 2011;96:1911–30
- Holick MF. Vitamin D deficiency. Review. N Engl J Med 2007;357:266–81
- Garcion E, Wion-Barbot N, Montero-Menei CN, et al. New clues about Vitamin D functions in the nervous system. Trends Endocrinol Metab 2002;13:100–5
- Eyles D, Brown J, Mackay-Sim A, et al. Vitamin D3 and brain development. Neuroscience 2003;118:641–53
- F'eron F. Developmental vitamin D3 deficiency alters the adult rat brain. Brain Res Bull 2005;65:141–8
- Turkish State Meteorological Service. www.mgm.gov.tr. Official statistics of Ankara. Available from: www.mgm.gov.tr/veridegerlendirme/il-ve-ilceler-istatistik.aspx?m¼ANKARA#sfB [last accessed 7 Dec 2014]
- Nucci AM, Russell CS, Luo R, et al. The effectiveness of a short food frequency questionnaire in determining vitamin D intake in children. Dermatoendocrinol 2013;5:205–10
- United States Department of Agriculture. MyPlate.gov. How much food from the Dairy Group is needed daily? Updated 4 June 2011. Available from: http://www.choosemyplate.gov/food-groups/dairy-amount.html [last accessed 7 Dec 2014]
- Celik Y. Principles of biostatistics. 2nd ed. Diyarbakır: Dicle University Press; 2007
- Tomatir AG, Demirhan H, Sorkun HC, et al. Major congenital anomalies: a five-year retrospective regional study in Turkey. Genet Mol Res 2009;8:19–27
- Moore KL, Persaud TV. Congenital anatomic anomalies or human birth defects. In: The developing human: clinically oriented embryology. 8th ed. Philadelphia: Saunders Elsevier; 2008:200–5
- Tunçbilek E, Boduroglu K, Alikasifoglu M. Results of the Turkish congenital malformation survey. Turk J Pediatr 1999;41:287–97
- Himmetoglu O, Tiras MB, Gursoy R, et al. The incidence of congenital malformations in a Turkish population. Int J Gynaecol Obstet 1996;55:117–21
- Botto LD, Moore CA, Khoury MJ, Erickson JD. Neural-tube defects. N Engl J Med 1999;341:1509–19 (Review)
- Holick MF. The influence of vitamin D on bone health across the life cycle. J Nutr 2005;135:2726–7
- Johnson DD, Wagner CL, Hulsey TC, et al. Vitamin D deficiency and insufficiency is common during pregnancy. Am J Perinatol 2011;28:7–12
- Halicioglu O, Aksit S, Koc F, et al. Vitamin D deficiency in pregnant women and their neonates in spring time in western Turkey. Paediatr Perinat Epidemiol 2012;26:53–60
- ACOG Committee Opinion No. 495. Vitamin D: screening and supplementation during pregnancy. ACOG Committee on Obstetric Practice. Obstet Gynecol 2011;118:197–8
- Javaid MK, Crozier SR, Harvey NC, et al; Princess Anne Hospital Study Group. Maternal vitamin D status during pregnancy and childhood bone mass at age 9 years: a longitudinal study. Lancet 2006;367:36–43
- Hollis BW, Wagner CL. Vitamin D and pregnancy: skeletal effects, nonskeletal effects, and birth outcomes. Calcif Tissue Int 2013;92:128–39
- Bener A, Al-Hamaq AO, Saleh NM. Association between vitamin D insufficiency and adverse pregnancy outcome: global comparisons. Int J Womens Health 2013;5:523–31
- Kesby JP, Eyles DW, Burne TH, McGrath JJ. The effects of vitamin D on brain development and adult brain function. Mol Cell Endocrinol 2011;347:121–7
- Walder RY, Yang B, Stokes JB, et al. Mice defective in Trpm6 show embryonic mortality and neural tube defects. Hum Mol Genet 2009;18:4367–75
- Farrell CJ, Soldo J, McWhinney B, et al. Impact of assay design on test performance: lessons learned from 25-hydroxyvitamin D. Clin Chem Lab Med 2014;52:1579–87