Iron is crucial for optimal thyroid gland function and optimal thyroid hormone production. This explains that iron deficiency, in addition to causing anemia, can also lead to low thyroid hormone levels and even hypothyroidism. Because iron deficiency can be quite common during pregnancy as a result of the increased needs for the developing fetus, you need to make sure that you are not iron deficient prior to becoming pregnant or while pregnant. One of the many reasons is that iron deficiency may impair your thyroid function and can cause low thyroid hormone levels that could be detrimental to the pregnancy outcome and to the healthy development of your baby. In fact, research has shown that low iron levels during the first six months of pregnancy is associated with lower thyroid hormone levels than women with normal iron status.