Prot# DR-PSE-309: Mltctr, Opn-Lbl Study to Eval. Efficacy & Safety of Extended Cycle, Low Dose, Cmbnt'n Oral Contraceptive Regimen, DP3-Lo 84/10, Which Utilizes Ethinyl Estradiol During 7 Day Interval Bt/wn Each 84-Day Cycle of Cmbnt'n Therapy for Prevent