3Pitkin RM, Gebhardt7 MP. Serum cakium concen -trations in human pregnancy. Am J Obstet Gynecol, 1997, 127 (7) : 775.
4Folin M, Contiero E, Vaselli GM. Trace element determination in humans [J]. Biological Trace Element Reasearch, 1991, 31 (2) : 144.
5[1]Roth HP, Kirchgessner M. Influence of alimentary zinc deficiency on the concentration of growth hormone, insulin - like growth factor- 1(IGF- 1) and insulin in the serum of force- fed rats[J].Horm Metab Res, 1994, 26(9) :404 - 408.
2Forster DA, Wills G, Denning A, et al. The use of folic acid and other vitamins before and during pregnancy in a group of women in Melbourne Australia [ J . Midwifery, 2009, 25 (2) : 134 - 146.