Menstruation in healthy women does not cause iron deficiency anaemia. Blood loss during a period in healthy women is not more than 80ml (around 3 table spoons). In case, the blood loss is more than 80ml, you should consult your doctor immediately..

Illustration of a blood drop - Menstrupedia
  1. Iron-deficiency is not something you get just for being a lady, http://blogs.scientificamerican.com