Women are more prone to iron deficiencies for 2 main reasons:
Monthly menstrual periods
Women with (heavy) menses are more prone to developing iron deficiency. Every 1mL of blood contains 0.5mg iron; any woman with heavy menses can experience volumes exceeding 80mL per month, which equates to ~500mg iron (or more) per year. This is comparable to the blood loss from undergoing major surgery every year. It is really difficult/near impossible to absorb this amount of iron from our diet to replace this, hence, women are more likely to be deficient.
Pregnancy
Pregnant women (or those with multiple children) are at increased risk. The total iron needed to support each pregnancy can range from 500 to 1000mg. In Singapore, a recent study demonstrated that up to 74% of women in the 3rd trimester of pregnancy were estimated to suffer from absolute iron deficiency [1]. Additionally, there is blood loss associated with delivery and mums who have pregnancies in quick succession would not have enough time to replete their iron stores either through diet or oral supplementation.
References:
1. Loy SL, Lim LM, Chan S-Y, et al. Iron status and risk factors of iron deficiency among pregnant women in Singapore: a cross-sectional study. BMC Public Health. 2019;19(1). doi:10.1186/s12889-019-6736-y
