One of the first things many pregnant women do, some even before their child is conceived is taking prenatal vitamins. Prenatal vitamins are multi-nutrient supplements, which means they provide several vitamins and minerals. Prenatal vitamins differ from general multivitamins because they have a higher concentration of folic acid, a key to preventing neural tube defects.
Most studies on nutrient deficiencies in pregnancy are performed in developing countries. This is due to the higher rates of poverty and the increased malnutrition caused by poverty. Most studies also focus on a single nutrient and its effects rather than the entire nutritional profile. This has led some researchers to question the need for multivitamin supplementation in pregnancy for women, especially in developed countries where over-feeding and potentially over consumption of some minerals and vitamins is likely.
Research is conflicting on the overall effects of multiple nutrient supplementation in pregnancy. In some studies, multiple vitamins show no more benefit than supplementation with folic acid alone, or folic acid and iron supplements. Other studies show multiple vitamins reduce low birth weight, neonatal death and maternal morbidity.
It is possible nutrient supplements are most important for pregnant adolescents, who are still growing and need high levels of many nutrients to ensure proper development of their own bodies. It is also possible multivitamins will be most beneficial to poor women who have the most difficulty obtaining a good variety of foods during pregnancy.
Nutrients to Consider Supplementing
Folic Acid is the synthetic form of folate that is used in supplements. Folate deficiency in pregnancy is related to neural tube defects, and it may play a role in placental health. In a review of research on dietary intake in pregnancy, women in all developed countries studied did not get enough folic acid from their diet alone. A woman will need a greater intake of folate if she has sickle cell disease or lives in an area where malaria is endemic.
Vitamin D may play a role in prevention of pre-eclampisa, but the evidence is not consistent. The bone mass of the baby is related to the vitamin D status of the mother. Intake from diet alone is below the minimum recommendations for pregnancy in developed countries.
Iron deficiency may be related to preeclampisa, prematurity, and poor neural development. Iron supplementation has been shown to provide benefits for both the mother and the baby. The United Kingdom was the only country where pregnant women achieved the minimum recommended iron intake. To maximize the effects of a mother's good iron nutrition during pregnancy, it is recommended to delay cord clamping until the cord stops pulsing. This provides 30% more iron for the baby and helps prevent iron deficiency in the newborn.
Calcium has been shown to have a protective effect against preeclampsia and low birth weight. Calcium intake from diet is geographically influenced. Women in many developed countries have enough from diet alone, however women in Japan do not consume minimum intake recommendations and diets in Australia and New Zealand were borderline adequate.
Nutrients Adequate in Diet Alone
Vitamin A is important for many aspects of development. Deficiency may be related to preterm birth and low birth weight. It is recommended women increase intake during pregnancy, but not exceed the upper limit because high levels can cause harm to the baby. Pregnant women in developed countries generally achieve recommended intake of vitamin A from diet alone.
Vitamin B12 may play a role in neural tube development. Intake from diet alone is greater than the minimum recommendations for pregnancy in developed countries.
Vitamin C is believed to prevent preeclampisa, but high dose supplementation has not shown a reduction. Intake from diet alone is greater than the minimum recommendations for pregnancy in developed countries.
Vitamin E is believed to prevent preeclampisa, but high dose supplementation has not shown a reduction.
Iodine is needed for proper thyroid function, and deficiency in the mother is associated with miscarriage, small for gestational age, delayed mental development and hearing loss. Iodine is added to salt for supplementation in nearly all parts of the world.
Zinc needs during pregnancy are nearly double the non-pregnant needs. Zinc is essential to metabolic functions and brain development. Pregnant women in developed countries generally consume enough zinc from diet alone.
Riboflavin, Niacin, Thiamine intake is above recommended levels in the diet in nearly all developed countries studied.
Choline is necessary for proper brain development. Selenium may play a role in recurrent early pregnancy loss and preeclampisa prevention. However, selenium needs decrease during pregnancy. Copper needs increase during pregnancy. Copper is essential for embryonic development and may play a role in birth defects. These nutrients were not included in the systematic review of pregnancy diets in developed countries.
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Lassi, Z.S., Salam, R.A., Haider, B.A., and Bhutta, Z.A. (2013). Folic acid supplementation during pregnancy for maternal health and pregnancy outcomes (Review). The Cochrane Library, 3.
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