Iron deficiency is the most common nutritional deficiency in the world. Globally, more than 30% of non-pregnant (468 million) and almost 50% of pregnant women (56 million) suffer from anemia, much of which is caused by iron deficiency.
Adolescent girls and women of reproductive age lose iron through monthly menstruation, and because their diets are often lacking in iron, they are particularly vulnerable to iron deficiency. A hint to the importance of iron for fertility is found in women with celiac disease (immune reaction against a protein found in wheat). Women with celiac disease have reduced ability to absorb iron and also have altered reproductive function, including delayed menarche, early menopause, and infertility of unknown cause. In an 8-years follow up on women attempting to get pregnant, conducted in the UK (Obstertrics & Gynecology, 108:1145-1152, 2006), women taking iron supplements had approximately 50% less chance to develop ovulatory disorders, which are responsible for half of the cases of female infertility.