Minerals and Trace Elements in Pregnancy

Although calcium deficiency in pregnancy is rare, it appears in cases of hypoparathyroidism and severe dietary inadequacy and individuals who are unable to eat a diet rich in dairy products [i],[ii]. Low calcium and magnesium levels have been associated with hypertensive disorders of pregnancy, although a causal effect has not been shown (10; MJ Keirse, unpublished observations, 2000). Moreover, there is some evidence that in populations with low calcium intakes, supplementation may reduce pregnancy-induced hypertensive disorders and preeclampsia (J Belizan, personal communication, 1999).

Iron

Iron deficiency resulting mainly from poor dietary iron bioavailability causes anaemia [iii], and has been associated with maternal mortality [iv]. Iron deficiency is also known to affect immune status by reducing the delayed-type hypersensitivity reaction, graft rejection, and cytotoxic activity of phagocytes[v]. A low plasma iron concentration also selectively inhibits proliferation of T_H1 and not T_H2 cells; thus, iron may be important for maintaining maternal health and reducing the risk of infection.

Prophylactic iron supplementation is recommended in developing countries[vi], for all pregnant women in the second and third trimesters of pregnancy.

Low plasma zinc concentration during pregnancy, result from low dietary bioavailability[vii] or very high amounts of copper or iron in the diet that compete with zinc at absorption sites [viii], have been associated with:

Zinc deficiency can also affect the immune response because it results in reduction in T cell development, thymic hormone release, and T cell functions ¹⁰.

Zinc supplementation may improve pregnancy outcomes for chronically deficient pregnant women (JC King, unpublished observations, 2000). The FAO/WHO recommended supplementation in pregnancy is 2.0 mg RDA.

Copper deficiency has not been observed in pregnancy, there is no need for supplementation in pregnancy [xii]. Nevertheless, if zinc supplements are given to individuals with low copper intakes, a copper supplement should also be given to compensate for the zinc-copper interaction [xiii].

Iodine

In regions of moderate to severe iodine deficiency, pregnant women need iodised salt before or during pregnancy. [xv]

References

[i] Kazzi GM, Gross CL, Bork MD , Moses D. Vitamins and minerals. In: Gleicher N, Buttin L, eds. Principles of medical therapy in pregnancy. 3rd ed. Old Tappan , NJ : Appleton and Lange , 1998:311–9.

[ii] Stabile I, Chard T, Grudzinskas G, eds. Clinical obstetrics and gynaecology. London : Springer, 1995:96–7.

[iii] Bothwell TH. Iron requirements in pregnancy and strategies to meet them. Am J Clin Nutr 2000;72(suppl):257S–64S.

[iv] Rush D. Nutrition and maternal mortality in the developing world. Am J Clin Nutr 2000;72(suppl):212S–40S.

[v] Yoshida SH, Keen CL, Ansari AA, Gershwin ME. Nutrition and the immune system. In: Shils ME, Olsom JA, Shike M, Ross AC, eds. Modern nutrition in health and disease. 9th ed. Baltimore : Williams and Williams , 1999:725–50.

[vi] Stoltzfus RJ, Dreyfuss ML. Guidelines for the use of iron supplements to prevent and treat iron deficiency anemia. Washington , DC : INACG/WHO/UNICEF, 1998.

[vii] Tuttle S. Trace element requirements during pregnancy. In: Campbell DM, Gillmer MDG, eds. Nutrition in pregnancy. London : Royal College of Gynaecologists, 1983:47–54.

[viii] Sheldon WL, Aspillaga MO, Smith PA, Lind T. The effect of oral iron supplementation on zinc and magnesium levels during pregnancy. Br J Obstet Gynaecol 1985;92:892–8.

[ix] Jameson S. Zinc status in pregnancy: the effect of zinc therapy on perinatal mortality, prematurity and placental ablation. Ann N Y Acad Sci 1993;678:178–92.

[x] Kiiholma P , Paul R, Pakarinem P , Gronroos M. Copper and zinc in pre-eclampsia. Acta Obstet Gynecol Scand 1984;63:621–31.

[xi] Zimmerman AW, Dunham BS, Nichimson DJ, et al. Zinc transport in pregnancy. Am J Obstet Gynecol 1984;149:523–9.

[xii] Institute of Medicine . Nutrition during pregnancy. Washington , DC : National Academy Press, 1990.

[xiii] National Research Council. Recommended dietary allowances. 10^th ed. Washington , DC : National Academy Press, 1989.

[xiv] Delange F. Administration of iodized oil during pregnancy: a summary of the published evidence. Bull World Health Organ 1996; 74:101–8.

[xv] Dunn JT. Iodized oil in the treatment and prophylaxis of IDD. In: Hetzel BS, Dunn JT, Stanbury JB, eds. The prevention and control of iodine deficiency disorders. Amsterdam : Elsevier, 1987:127–34.

Calcium and Magnesium

Iron

Iodine