Menstruating Women - Due to blood loss during menstruation women of child bearing age are at risk of iron deficiency, the greater the blood loss the greater the risk.
Individuals with Kidney Failure - People with kidney failure, and especially those on dialysis, are at high risk of iron deficiency anemia. This is due to an inability of the kidney to create adequate amounts of the hormone erythropoietin which is necessary for red blood cell creation, and therefore, retaining iron.
Pregnant and lactating women - A developing fetus requires a high amount of iron, likewise, there is a high amount of iron lost through breast milk after birth.
Older infants and toddlers
People with low levels of Vitamin A - Vitamin A greatly helps move iron from storage in the body, without adequate amounts of vitamin A the body cannot regulate iron properly leading to an iron deficiency.
People with gastrointestinal disorders - Diarrhea, ulcers, and other gastrointestinal disorders and diseases can lead to an inadequate iron absorption.
Source:
https://www.healthaliciousness.com/articles/food-sources-of-iron.php
