Baby and You

Iron Deficiency

Many women are iron deficient during pregnancy. Solvotrin Therapeutics explain why this occurs and why iron is important during pregnancy for both you and your developing baby

Iron deficiency is common in pregnancy with risks to mum and baby. At Solvotrin Therapeutics, we have studied iron and the impact of iron deficiency for many years with the aim of making iron better. Specifically, our aim has been to reduce the side effects of iron.

One of the most common times to experience an iron deficiency is during pregnancy. This is due to the fact that the demand for iron increases threefold during pregnancy to meet the demands of the growing foetus and placenta as well as maternal adaptions to pregnancy.1 With blood volume increasing by 40 – 50% during pregnancy, there is an increased requirement for iron.2

Many women, especially those who experience heavy menstrual bleeding, already have low iron reserves at the time of conception, putting them at even greater risk of iron deficiency during pregnancy. It is estimated that 10-20% of menstruating women are iron deficient.3

Iron deficiency puts women at risk of becoming anaemic which is a particular concern in pregnancy as it is a key risk factor in post-partum haemorrhage (PPH).4

Why is iron important?

Iron is very important during pregnancy for both you and your developing baby. This important nutrient contributes to the reduction of tiredness and fatigue and plays an important role in normal energy yielding metabolism. It also supports oxygen transport in the body and is required to make extra blood (haemoglobin). Iron also supports both cognitive function and immune function.

Can I always get enough iron from my food during pregnancy?

Yes, you can get iron from food and there are many foods rich in iron. It is worth including green leafy vegetables such as spinach into your diet along with quinoa and legumes. Animal sources; red meat, poultry and fish are also good sources of iron. However, during pregnancy there are some restrictions, it is important to avoid fish with high levels of mercury such as mackerel, sardines and canned tuna. There is also a safe upper limit of 500g of red meat per week. For further guidance on safe food in pregnancy please refer to

However, it can sometimes be difficult to absorb iron from food and it may not be sufficient to meet your increased requirements during pregnancy. “Even if you enjoy balanced meals, most people absorb only 10 per cent of iron from their diet,” explains Dr Dawn Harper. When your dietary intake doesn’t meet your iron needs, you may need to supplement.

What is the risk of me developing an iron deficiency during my pregnancy?

Women who are at risk of iron deficiency during pregnancy5

  • Low iron stores before pregnancy
  • Previous history of anaemia
  • Pre-existing blood condition (e.g. sickle cell disease)
  • Age < 20
  • Dietary deficiency
  • Short space of time between pregnancies < 18 months
  • Multiple pregnancy

Once a woman becomes iron deficient during pregnancy, dietary sources of iron will be insufficient to replenish levels and oral iron supplementation is recommended.6

Do iron supplements have side effects?

Some iron supplements can have limitations. Many including the most commonly prescribed ferrous sulphate3 have low absorption rates (around 10-15%)7 and side effects are common. In a recent study 75% of participants experienced side effects which included nausea, constipation and abdominal pain.8

If you are experiencing side effects from your iron supplements it is worth seeking an alternative. The need for more effective, better tolerated oral iron formulations is global and affects up to two billion people worldwide.9

How can I choose the best iron supplement for pregnancy?

If you do need to supplement your iron intake for pregnancy, it’s important to choose one that is both kind on your system as well as having strong absorption. Constipation effects up to 38% of pregnancies as rising progesterone levels in pregnancy contribute to slow gut motility.10 Therefore, choosing the right iron supplement for pregnancy is particularly important.

When ordinary iron reaches the stomach and lower gut it is known to cause oxidative stress and trigger side-effects such as constipation. It is important to choose a supplement that is kind on the stomach as well as strong on absorption, supporting your iron levels throughout your pregnancy.


  1. UN Children’s fund, UN University, World Health Organisation. Iron deficiency anaemia: assessment, prevention and control. A guide for programme managers.
  2. Guyton & Hall (2005) Textbook of Medical Physiology (11ed) Philadelphia: Saunders. Pg 103 ISBN 81-8147-920-3.
  3. Scientific Advisory Committee on Nutrition. Iron and health. 2010 Accessed April 2019.
  4. Nagenthian et al, “Anaemia – a prevalent risk factor for post partum haemorrhage”, EJOG Nov 2016, volume 206 pg e83.
  5. Tolkien Z et al. Ferrous sulphate supplementation causes significant gastrointestinal side effects in adults: a systematic review and meta-analysis. PLoS One 2015; 10 (2): e0117383 doi: 10.1371/journal.pone 0117383.
  6. Goddard AF et al. Guidelines for the management of iron deficiency anaemia. Gut 2011; 60: 1309 -1316.
  7. Santiago P Ferrous versus ferric oral iron formulations for the treatment of iron deficiency: a clinical overview. The Scientific World Journal 2012, Article ID 846824. DOI: 10.1100/2012/846824.
  8. Pereira et al. BMC Gastroenterology 2014, 14:103.
  9. WHO | Worldwide prevalence on anaemia 1993-2005. (2018). Retrieved from
  10. Verghese, TS, Futaba, K, Latthe, P. Constipation in pregnancy. The Obstetrician & Gynaecologist 2015; 17: 111-5


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