Vitamin and mineral supplements during pregnancy

I worked for a while in umbilical cord blood banking. This meant I spent a lot of time around pregnant women. I was always surprised at how many of them would list a multi-vitamin supplement on their medical histories. It was something I hadn’t thought necessary when I was pregnant myself (except of course for folate tablets and I did start taking iron when concerns were raised about my haemoglobin levels).

I thought I would explore the topic of vitamin and mineral supplements during pregnancy.

Pregnancy is a time of incredible change. Not only does a new human being grow out of two tiny cells to around 3kg in weight by birth, but the mother’s own body adapts to accommodate and nourish the growing baby. Many women are understandably concerned about getting nutrition right during this time.

Is this really necessary? I mean women have been having babies since way before multi vitamin tablets were invented.

Let’s first have a look at the physiological demands and requirements of pregnancy and gestation.

In the initial stages of pregnancy the embryo is so tiny that not much extra energy or nutrients are needed to support its growth. However, during this time it is susceptible to agents (known as teratogens) that may cause birth defects or malformations and agents that can cause miscarriage or spontaneous abortion. Vitamin A in large amounts is teratogenic so it is important that any supplement a pregnant woman or woman trying to get pregnant takes has Vitamin A concentrations no higher than 2800ug of retinol equivalents (it’s probably best to simply avoid any supplemental Vitamin A completely).

During the second half of pregnancy foetal growth is rapid and energy needs increase. The baby needs iron for its expanding blood volume, calcium to build its skeleton, protein for building body tissues, essential fatty acids and iodine for brain development and folate for the DNA synthesis that such rapid growth demands. Most of these nutrients can be supplied easily by a small increase in nutrient dense foods in the mother’s diet. The same can be said for most of the vitamins and minerals found in commercial supplements. The nutrients which are of concern however, and are difficult to meet recommendations through diet are folate, iodine and iron. Let’s look at each of these in turn.

Folate is essential for healthy proliferation of cells. You can imagine that this would be important in a foetus undergoing rapid growth and development. Maternal stores often drop during pregnancy as the foetus has such high demands. There is an association between neural tube defects (such as anencephaly and spina bifida) and low folate, although the relationship is not entirely clear. The neural tube closes very early in pregnancy so it is important that folate levels are high early in pregnancy and even while planning pregnancy (since many women do not even know they are pregnant during this critical time). Very high levels of folate (greater than what can typically be found in the diet) are needed to exert this protective effect. Folate fortification of foods has commenced in many countries. Folate can also be found in leafy green vegetabls, legumes, seeds and liver. On top of consuming folate rich foods in pregnancy in Australia it is recommended that a daily supplement of 400ug (0.4mg) of folate is taken during pregnancy planning and the first three months.

Iodine. An adequate supply is required during pregnancy for normal brain development. Population studies in Australia have found that low iodine levels in mothers and babies is not uncommon. Iodine rich foods include iodised salt and products that have been made with iodised salt, seafood, dairy products, plants grown in iodine rich soil (and animals fed those plants). In addition to consumption of iodine rich foods supplementation with 150ug per day when considering pregnancy and throughout pregnancy and breastfeeding is recommended in Australia.

Iron is required during pregnancy for growth and the expanding blood volume of the foetus and the mother and for the accumulation of iron stores in the foetus. Iron deficiency anaemia in the mother can compromise delivery of oxygen to the foetus  and is a risk factor for preterm delivery and subsequent low birth weight and may affect infant health and development. Anaemic mothers may also have difficulty coping with any obstetric complications that may arise during childbirth. The extra requirement for iron during pregnancy in Australia has been set at a very high level that can only be achieved through supplementation. However this amount does not take into consideration the fact that maternal absorption of dietary iron in the small intestine increases dramatically throughout the pregnancy. It is likely that a woman who was not suffering from iron deficiency anaemia at the outset of pregnancy would be able to meet iron needs through diet alone. Foods rich in iron include red meat, leafy greens, legumes, eggs, whole grains, enriched cereals, dried fruit, parsley and pumpkin seeds.


During pregnancy a varied, nutrient dense diet in line with national recommendations should provide most vitamins and minerals required for the health and safety of mother and baby. It is prudent however to supplement the diet with folate while planning pregnancy and during the first three months for and iodine during the entire pregnancy (and continuing into breastfeeding). Iron supplementation may or may not be required and as with all pregnancy related matters should be discussed with an obstetrician or general practitioner. Also be aware that recommendations can vary from country to country.

Here is a related article on vitamin and mineral supplements


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