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Iron in the Preterm Infant – Why, Who, When, How Much and How Long?

Clearly this is a hot topic. So, we decided to dive into iron for the preterm infant: why, who, when, how much and how long to supplement.

Why is supplementation important in preterm infants?

80% of total body iron present at birth is accumulated in the third trimester of pregnancy. Because of shorter gestation, late and moderately preterm infants have lower iron stores at birth than term infants. Iron stores are also accrued based on weight, therefore, having a lower birth weight increases the chances of having lower iron stores.

Additionally, maternal iron deficiency, gestational diabetes, hypertension, smoking and obesity can compromise iron status in the infant.

Frequent bloodwork, low doses of enteral iron (especially in the exclusively breastfed infant), late start of iron supplements and rapid postnatal growth are common iatrogenic post-natal factors that also affect iron stores.

Lower iron stores in preterm infants increases the incidence of iron deficiency anemia in toddlerhood, continuing to perpetuate the problem and can negatively impact growth and development.



Who to supplement?

Do all preterm infants require iron supplement? Or only a subset?

The European Society for Paediatric Gastroenterology Hepatology and Nutrition (ESPGHAN) recommends to supplement infants born <2500 g, regardless if they were born preterm or term.

All infants with iron deficiency anemia, regardless of their birth weight, should also be supplemented.

The American Academy of Pediatrics (AAP) recommends that all infants who are not breastfed or only partially breastfed, irrespective of whether they are premature or not, should receive an iron-fortified formula (containing between 4 to 12 mg of iron per liter) from birth to 12 months.



When to start supplementing?

Supplementation should be started between 2 and 6 weeks of age as per ESPGHAN and AAP. This is to ensure that the immune system has matured a bit and the antioxidant pathways have been established.

An article in Pediatrics back in 1993 showed that when supplementation is delayed past 2 months of age, there is a greater rate of iron deficiency anemia at 6 months of age.



How much to supplement?

In 2012 ESPGHAN recommended the following doses based on birth weight:


Does the dose change for breastfed vs formula fed infants?

YES!!! The Canadian Pediatric Society recommends that low birth weight infants (<2500 g) who are predominantly formula-fed (i.e., greater than 50% of intake), may not require iron supplementation when the formula is high in iron (formula would need to contain about 10-14 mg/L of iron)



What about those that are deficient?

Increase the amount!

The recommended treatment dose ranges between 3-6 mg/kg/day generally divided in 3 doses.




How Long?

Ensure an adequate dietary source of iron before stopping supplementation.

Should you repeat bloodwork? Follow up hemoglobin and ferritin levels are recommended to assess discontinuation of supplementation.




Important Considerations:

Preventing excess iron is just as important, as it can cause adverse effects such as poor growth, increased risk of infections and even poor neurodevelopment, only those that require supplementation should receive it.

Preterm infants who receive blood transfusions may require lower doses of iron.

Titrating iron doses based on serum ferritin levels is currently being investigated.



Bottom line:

Supplement those born <2500 g

Start supplementing between 2 and 6 weeks of age

Dose and length of supplementation are based on birth weight

Those that have documented iron deficiency anemia may need more

More studies to come on how to titrate the dose




Iron is the most common micronutrient deficiency in the world, as Dietitians, we can help correct and prevent harmful consequences.





Charlene and Julie


P.S. Want to learn more about infant nutrition? Join our wait list for our signature course Infant Nutrition Essentials.

P.P.S. Want to learn more about preterm nutrition? Check out our free webinar, Classic Late Preterm Infant – Nutrition Pearls from NICU to Home.

P.P.S. Join our growing Facebook group Pediatric Dietitians – Newbies to Masters.

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