The need for iron supplementation increases in pregnancy for the proper growth of the fetus. The normal range of iron in a non-pregnant woman is around 40-140 mcg/dL. In the first trimester, the serum iron value should be around 72-143 mcg/dL. In the second trimester, the normal range is 44-178 mcg/dL, and in the third trimester, it is around 30-193 mcg/dL.