What are the hormonal effects the IUD has on our bodies?

Minimal. IUSs are an excellent (long-term, completely and easily reversible) contraceptive option even for women at risk for complications from female hormones - because their effect is primarily local and not over the entire body. I wish more women in the US would use IUDs instead of tubal ligations! Beware: IUDs are best for mutually monogamous relationships because they do not prevent STDs/HIV.