How much iron do you really need in pregnancy?
Warning! Don’t dismiss this article because you’ve been told by your lead maternity carer that your iron is fine! Learning the ins and out of this important mineral could make all the difference to your pregnancy experience.
Iron is one of those minerals we take for granted. But in fact it is the only nutrient deficiency still highly prevalent in developed societies, including New Zealand and Australia. Iron deficiency is rampant in pregnancy and a further 12% of pregnant women develop the extreme form of deficiency called anaemia.
In pregnancy your blood volume increases by a whopping 50%
Your body makes this extra blood to supply baby with the oxygen needed to grow and is specifically important in brain development. This increase in blood volume is called haemodilution. Along with haemodilution, our body increases (if it can) the production of red blood cells, trying to maintain levels of iron containing haemoglobin for adequate oxygen delivery. Suboptimal iron levels mean we don’t produce the haemoglobin needed to deliver that much needed oxygen.
You may have had blood tests done in your pregnancy that indicated your iron levels were ‘normal’. These blood tests generally measure the level of something called ferritin which is a measure of our iron stores. The range for ferritin in New Zealand 20-250ug/L (varying slightly between labs) which you can see leaves a huge margin for ‘normal’. You are considered to have normal levels until you’re anaemic. There’s no category for depletion or suboptimal levels which is illogical because symptoms of suboptimal iron appear long before iron deficiency results in anaemia. In naturopathic circles we have protocols for depletion, deficiency and anaemia. 3 phases of declining iron that we can detect and reverse before one phase progresses to the next. Prevention is the best cure.
So how do you know if you need to increase your iron?
I encourage all my clients to keep a copy of their blood tests. It’s as easy as asking for a copy at the lab before you get the test done, or if you forget you can get a copy from whomever ordered the test for you. Keep a file, look at the trends, become your own health advocate. In pregnancy you will generally have antenatal blood tests during each trimester. The timing of these depends on when you have your first visit, any symptoms you may be having, previous pregnancy complications etc. Along with iron and full blood count, you will be offered a test for various STD’s including HIV, the risk of downs syndrome, gestational diabetes, among others.
When thinking about iron we need to look at more than ferritin (iron storage). There are a variety of tests which give clues to your iron status and the underlying factors involved in deficiency. The reference ranges are generally stated beside the reading so you can see where you stand in the range. Each lab has variations on procedure and units in which they measure, so be sure to check the labs specific ranges before comparing with any online information or friends results etc. Here are the main results you will see on your tests:
Haemoglobin
The majority of our body’s iron (65%) is found in our haemoglobin. So this is also a helpful measurement to look at. You will find your haemoglobin level in the “Blood Count’ section of the test (it may also be called full blood count FBC, or complete blood count CBC). Sometimes Haemoglobin will be shortened to Hb in results. Haemoglobin usually maintains quite well until stores of iron (ferritin) are quite depleted. So if it has dropped at all, you know your stores are being tapped into.
Red blood cell count
Due to haemodilution in pregnancy the ‘normal’ range for red blood cell count is reduced. With this in mind, and the fact that the body does indeed increase red cell production in pregnancy, you want to see this reading in the higher end of the normal range.
Serum Iron
This is a measure of the iron currently circulating in the blood. This test is done less and less these days as it’s easily effected by time of day and the content of your last meal for example. Ferritin has become the preferred test.
Ferritin
Ferritin provides an estimation of total iron storage in the body. It’s stored in the bone marrow and tapped into as we need it. It is often the first measurement to drop in cases of deficiency as the body draws on stores to complete vital functions.
Total iron binding capacity (TIBC)
This is a measure of a certain protein that bonds and carries iron around the body. So this test gives a measure of how well your iron is travelling through the body. Higher TIBC indicates low levels of iron in the blood.
Iron Saturation/Transferrin Saturation
This is a measure of the ratio of serum iron to TIBC. So we can see what percentage of the the iron binding sites are being used, therefore the saturation of iron in the blood. Or another way to put it is that this is a way to see how much is actually being carried in the blood, available for use. Lower results can indicate iron deficiency.
RBC, HCT, MCV, MCH
You will also find these abbreviations under your full blood count readings. They are rarely discussed but all serve a purpose and it’s good to know their meanings. Once you do you can see where you sit in the range.
RBC reflects the total number of red blood cells in your blood. Low scores indicate anaemia, B6, B12 or folate deficiency.
HCT is the measure of haematocrit which is the volume percentage of red blood cells in the blood. It’s essentially another measure of red blood cells but sometimes will be low when other readings remain normal. For this reason it’s considered important as it can sometimes pick up anaemia when other test results wont.
MCV stands for mean corpuscular volume. This measure reflects the intracellular volume of your red blood cells which is indicative of your haemoglobin levels. Low readings indicate iron depletion.
MCH, or mean corpuscular haemoglobin gives us the average amount of haemoglobin per red blood cell. This is another way to screen for iron deficiency. Low results indicate anaemia. While conversely the MCH will increase (the red blood cell enlarge greatly) when B12 and folate are deficient. This can happen concurrently with anaemia.
Let’s not underestimate the demands of pregnancy on your body!
Recently a client of mine in her 3rd trimester had a shock when we went over her latest blood tests. She had always been very healthy, a great eater (although very little red meat her whole life) and her first trimester blood tests showed her iron levels and stores were fine. In fact, they were the best she had ever seen on a blood test, leading us to be quite complacent about keeping an eye on it. The third trimester came along and after a few niggling signs of restless legs, insomnia, weepiness and tiredness (put down to a waking toddler) we decided it was time to retest. The results were quite amazing. In a matter of 12 weeks every measure mentioned above had worsened. Her RBC’s had dropped into the low range. More concerning was the ferritin reading which was below the level of detection. We’d left it too late to prevent anaemia and it was going to take considerable effort to get those levels up again before baby came. Interestingly, one of the readings, the MCH had increased, now falling into the too high range which told me her B12 and folic acid had significantly dropped. These nutrients are also crucial in pregnancy and needed to be addressed. We got to work on supplementing her diet with iron (20mg 3xdaily, B12 50mcg 3xdaily and folate 500mcg 2xdaily) but what made them drop so low, so fast? And what are other measures we can take to reduce loss of these nutrients.
Diet and lifestyle
Vegetarian or not consider if you could get more iron from what you eat. See the list below to plan an iron rich pregnancy menu. As you can see, although red meat is the easiest, there are plenty of ways without red meat to build that blood back up.
Factors that effect absorption of iron from food
Having a digestive disorder of any kind can greatly effect the absorption of all nutrients including iron. Any gastrointestinal bleeding will of course effect iron, as will chronic inflammation, coeliac disease, H pylori infection, and low gastric acid. Or even periods of diarrhoea associated with IBS. These factors also make it hard to improve levels with supplements or diet so addressing the underlying condition is key.
Tea and coffee (and red wine, although you probably aren’t having much of that!) contain tannins which bind iron in the digestive tract making it unavailable for absorption. Keep these drinks to 1 daily and be sure to have 90mins away from supplements and iron rich meals. You don’t want to undo any good work you’re doing with your diet.
If you’re taking zinc, magnesium or calcium tablets these can also reduce the absorption of iron from supplements and food. Essentially they compete for absorption at our mineral channels in the gut. Take these nutrients at different times of the day to an iron supplement or iron rich meal.
A vegetarian diet is generally higher in certain iron binding foods. These include phytates found in grains and nuts and seeds, oxalates found in many vegetables, not to mention plain old fibre which binds to iron as well. Try to soak your grains, nuts and seeds before eating to reduce these so called ‘anti-nutrients’. It’s tricky because you need to maintain a healthy, varied diet but just watch that you aren’t adding un-soaked beans to spinach for example.
Vitamin C rich food such as capsicum, kiwifruit, citrus and leafy greens promote iron absorption and should be added to any iron rich meal.
Breastfeeding requires a lot of iron to maintain both your needs and baby’s. If you’ve had suboptimal iron during pregnancy it can be further depleted during breastfeeding, leaving mum more tired and run down than need be. Not what we need when we are sleep deprived and exhausted already! The body generally preferentially uses the iron for breast milk so luckily baby often remains iron replete. It has been found that some breastfed babies do suffer from low iron though so we can’t dismiss is possibility.
As you can see there is a lot to know about iron and it’s various ways of being measured. Become your own health detective, or seek holistic help and reap the benefits of having optimal iron levels during your pregnancy and beyond. I wish you all the very best on this amazing journey.
Annaliese Jones has an Auckland based clinic specialising in Nutrition, Naturopathy and Herbal Medicine. She offers care for anyone at any age with a special interest in fertility, pregnancy and children’s holistic health. See www.naturalhealthcheckup.com to watch a video about her practice and to sign up to her newsletter.
See table of iron rich foods below.
Iron rich foods (animal sources); 100 gram amounts (iron content in miligrams):
Kidneys 11.4
Mussels, Clams 11.2
Liver, beef/lamb 10.0
Oysters 4.8
Beef, lean 3.8
Sardines, tinned 2.9
Lamb, lean;
Prawns 2.2
Sausage, lean 2.0
Pork, lean 1.5
Chicken, lean; Squid 1.2
Fish, white to dark 0.6 to 1.8
Iron rich foods (plants); 100 gram amounts (iron content in miligrams):
Spirulina; Chlorella 29.0
Cocoa powder 16.0
Sesame; Tempeh 9.0
Molasses, blackstrap 6.5
Parsley; Cashew 6.0
Linseed/flaxseed 5.5
Amaranth, cooked 5.0
Oats, dry; Tofu 4.9
Pistachios; Pine nuts 4.6
Muesli; Chocolate, dark 4.5
Sunflower kernels 3.8
Almonds; Soybeans 3.7
Yeast flakes; Carob 3.6
Lentils, dark cooked 3.5
Quinoa, cooked 3.5
Olives, black; Dates 3.3
Legumes; Nuts 3.25 (average)
Apricots, dried 3.1
Popcorn; Cornbread 3.0
Seaweed, dried 2.85 to 54
Spinach, cooked 2.8
Chilli/Soy sauce; Bread, multi-grain 2.5
Miso; Brazils 2.4
Watercress; Sultanas 2.2
Figs, dried; Currants 2.1
Peanut butter; Egg 1.9
Raisins; Coconut 1.85
Potato; Asparagus 1.7
Peas green; Hummus 1.5
Avocado; Pesto 1.4
Lettuce; Rice 1.2
Leek; Prunes; Kale 1.0
Data from NZ Food Composition Tables; USDA Nutrient Database; dependent on season, soil, variety and style of preparation.
