Why do prenatal vitamins make some women sick?

Karla asked:

Has anyone ever asked their doctor why they become sick from prenatal vitamins?

http://www.gerson.org/Programs/monthlyprogram.htm http://www.sciencedaily.com/news/health_medicine/nutrition/ http://www.naturalnews.com/ http://www.mercola.com/

Prenatal Vitamins
Prenatal Vitamins