Whilst the media and marketing machines of large companies have an obsession with trying to get pregnant women to consume their vitamin products, it is the poorer cousins, the minerals, that often get forgotten.
We regularly see iron and calcium deficiency through the course of pregnancy and the postnatal period, which is why we thought it prudent to expand on the iron requirements in pregnancy and the postnatal period.
Why is iron important in pregnant women?
The reason for the increased requirements of certain minerals in pregnancy is due to both increased needs of the mother, as well as the iron requirements of the baby (which totally depend on the mother’s own iron reserves). The first change that requires increased iron is the expansion of the blood volume of the pregnant woman by 25% (and even more in a twin or multiple pregnancy). Then is the rapid growth in maternal tissues requiring iron in their production, namely because very little iron is transferred to the baby during breast feeding.
Many women may already have a low dietary intake of iron and, and some will find their gut absorbs it poorly. Red meat is the best common source of iron in most diet, and is the most easily absorbed from of iron. Iron from vegetable sources may be tougher to absorb, and requires larger amounts compared with meat. Vegetarian or vegan women have a higher likelihood of iron deficiency during pregnancy, especially if they don’t supplement through the course of their pregnancy. Even women with an optimal dietary intake with adequate stores at the beginning of pregnancy will have low stores by delivery. The Australian guidelines suggest 30mg per day whilst other countries suggest up to 60mg per day. Absorption from the gut is reduced in the first trimester, but improves during the second and third trimesters.
What supplements are best for pregnancy?
Many of the popular pregnancy multivitamin supplements contain iron. Specific iron supplements are often promoted by having fewer side effects or having better absorption. One specific addictive, vitamin C, has, in clinical trials, been shown to improve absorption from the gut, whilst most products with lower side effects usually have less elemental iron available. Other products promote themselves as more ‘bioavailable’ but again have less net absorption.
The most effective oral supplements contain between 80 – 100mg of elemental iron per tablet. One tablet taken daily is usually adequate to meet the needs and gradually replace the stores lost over a period of 8-16 weeks. Taking two tablets of these products doesn’t yield much faster replacement.
Are there side effects of iron supplements?
When iron supplements are taken orally, many people get constipation and some paradoxically get diarrhoea. Most will experience a significant change in stool colour: usually dark brown, black or sometimes dark green. When side effects of iron are too severe or when your iron stores are critically low, then, as an alternative, intravenous iron infusion may be helpful.
A newer product available in the last few years has a low complication rate, and low risk of allergic side effects. This iron infusion usually takes a half hour, and is performed in hospital as a day-stay procedure or in some larger General Practices. Usually only one infusion is required, and lasts up to six months.
Maintain your health with proper iron supplementing
Through the course of your pregnancy, lean red meat is the best and most readily available dietary source of iron. We recommend at least two good serves (250gms) of lean red meat are consumed each week to provide the basic iron supply in dietary form, providing you with the added benefit of high quality protein and an excellent source of vitamin B12.
Iron levels are best tested pre-pregnancy, the end of the first trimester and again at the end of the second trimester. Your obstetrician or midwife can guide you as to correcting any iron shortage stores.
