Iron Deficiency During Pregnancy
Iron deficiency is very common during pregnancy.
Iron needs increase significantly during pregnancy, and many pregnant individuals become iron deficient despite a healthy diet and taking a daily prenatal vitamin.
During pregnancy, your body needs extra iron to support:
- Your increased blood volume
- The growing placenta and
- Your baby’s development
Iron helps your body make hemoglobin, the part of red blood cells that carries oxygen throughout the body. Without enough iron, your body cannot carry oxygen as effectively, which can lead to iron deficiency anemia.
Low iron levels can significantly affect how you feel during pregnancy and may also affect your baby’s health and development.
Why treating iron deficiency matters:
Effects on the pregnant individual:
Iron deficiency in pregnant individuals may contribute to:
- Increased fatigue and low energy
- Reduced quality of life
- Poor concentration or “brain fog”
- Restless legs
- Low mood and increased risk of postpartum depression
- Increased risk of postpartum hemorrhage (heavy bleeding after delivery)
- Increased likelihood of needing a blood transfusion
- Increased risk of preeclampsia
Effects on the baby:
Iron deficiency during pregnancy may increase the risk of:
- Low birthweight or small for gestational age
- Preterm birth
- Fetal distress
- Infant iron deficiency
- Increased short and long-term effects on early brain and nervous system development, e.g. impacts on memory, processing speed, language and motor development, and cognitive function
The good news is that iron deficiency is very treatable, and improving iron levels can help support both maternal well-being and your baby’s development.
How we diagnose iron deficiency
Iron deficiency can be diagnosed using bloodwork. Specifically:
- Low ferritin levels (ferritin <60 in the absence of an inflammatory condition)
- Low reticulocyte hemoglobin (<28 pg)
- Changes in red blood cell size (i.e. MCV previously normal, but now low)
- Iron saturation (Tsat) levels in those with inflammatory conditions (ferritin <100 ug/L and Tsat <20%)
Your healthcare provider will interpret these results in the context of your pregnancy and overall health.
Our treatment goals
At THP, we aim for:
- Hemoglobin > 110 at the time of delivery
- Ferritin > 50 at the time of delivery
Optimizing hemoglobin and iron levels before delivery may help reduce complications and improve postpartum recovery.
Iron supplementation
If you have been advised to start iron pills, we typically recommend:
- First choice: Ferrous bisglycinate 28mg twice daily
- If this is not well tolerated: switch to Ferrous sulfate 300mg once daily
How to take iron pills:
- Take iron on an empty stomach (1 hour before or 2 hours after meals)
- Avoid taking iron at the same time as calcium supplements, milk, coffee, or tea. They can prevent your body from absorbing the iron.
- You do not need to take iron with Vitamin C. Current evidence does not clearly show that taking Vitamin C improves iron absorption.
Iron-rich foods:
- Foods high in iron include red meat, shellfish, poultry, eggs, beans, raisins, whole-grain bread, and leafy green vegetables.
- A healthy diet is important. However, please remember that diet alone is often not enough to correct iron deficiency in pregnancy.
Common side effects and how to manage them
- Iron pills may cause:
- Dark green or black stool
- Constipation
- Nausea
- Heartburn
- Stomach cramps
- To help prevent constipation:
- Increase water intake (2 liters daily)
- Stay physically active with regular walking
- Increase fibre intake through fruits, vegetables, and whole grains
- Consider fibre supplements such as Metamucil
- Laxatives such as Restor-a-lax are available over the counter if needed.
- Avoid Senokot during pregnancy as it may cause cramping.
How long to take iron for
- Even after your symptoms improve, it can take several months to rebuild your body’s iron stores. Do not stop taking iron pills without talking to your doctor or nurse first.
- Please also tell your healthcare provider if you develop any cravings for non-food items such as dirt, ashes, clay, or chalk. These cravings can be a sign of iron deficiency anemia.
When should IV iron be considered?
IV iron may be recommended if:
- You cannot tolerate oral iron
- Oral iron does not improve your hemoglobin
- Hb remains < 110 and ferritin remains < 50 despite oral iron
- Ferritin remains < 30 despite oral iron
- You are later in pregnancy (especially after 32 weeks), when there may not be enough time for oral iron to work effectively
Risks and side effects of IV iron
IV iron is generally safe and well-tolerated. Possible side effects include:
- Temporary low blood pressure: some people feel lightheaded the day of or after the infusion. Ensure you drink lots of fluids and increase salt intake the day before and the day after the infusion.
- “Fishbane reaction”: a small number of patients experience facial flushing, body aches, or chest tightness during the infusion.
- This is an expected, temporary reaction and is self-resolving.
- Once symptoms improve, the infusion can usually be restarted at a slower rate without the reaction recurring.
- Minor allergic reaction: hives, nausea, or stomach upset
- Anaphylaxis: extremely rare, occurring in <1/100,000 people.
To learn more about iron deficiency, please review the curated resources below.
Resources
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