Vitamin supplementation in pregnancy

The prescribing of vitamin supplements during pregnancy has become Standard in obstetric practice. İt is obvious the growth and development of the fetus depend on maternal supply of essential nutrients, e.g vitamins. in some studies it was reported that vitamin deficits during pregnancy might result in megaloblastosis, neural tube defects, placental and fetal defects, low birth weight and prematüre delivery. But these subjects are stili being studied because the recommendation, which suggest that these supplements improve maternal and fetal outcome, however are often based on studies with serious deficiencies. Moreover, the increase in vitamin requirements during pregnancy usually can be more than adequately provided by dietary sources, assuming appropriate caloric intake and the consumption of animal protein. Much knowledge regarding transport of vitamins across the placenta is derived from animal studies and simple case reports. The animal data are generally obtained using study designs in which vitamins are totally excluded or administered to excess. This type of study design has little potential application to the human experience, even in a severely malnourished mother or a mother who is taking "megadose" vitamins. Human studies of pregnancy complications associated with vitamin deficiencies are generally uncontrolled; frequently they are performecl in populations of patients with generally poor nutrition and multipl vitamin and mineral deficencies. For this reason, it is difficult to extrapolate from these data to popukıtions of pregnant women with well-balanced and nutritionally complete diets. Finally, there is no agreement on what constitutes normal serum levels of vitamins during pregnancy. Normal values for nonpregnant states do not correspond to values in the pregnant state. All maternal serum vitamin levels clecrease as pregnancy progresses and hypovitaminemia compared to non-pregnant women seems to be a normal status even in pregnant women who is using vitamins. This is because of the normal physiologic changes of pregnaney, which result in a decrease in many hinding globıılins and an increasc in plasma volume and also the increased placental vitamin transfer to the fetu.s from the mother. While it is generally agreed that the scientific evidence for universal vitamin supplementation ckıring pregnaney is ambigious, when undertaken with reason, it represents a benign therapy with potential for improved outcome. Newer data support more conckısively the therapeutic benefit of some vitamin supplementation to prevent spesific diseases. Example is vitamin ııse for the prevention of neural tube defects. On the other hand, frequently uncontrolled vitamin Lise, espeeially of megavitamins, may cause increased risks for pregnancies.