A Phase 2, Dose-finding, Cross-over Study to Evaluate the Effect of a NES/E2 Transdermal Gel Delivery on Ovulation Suppression in Normal Ovulating Women

Inclusion Criteria: * Woman is between 18 and 40 years of age * Has intact uterus and ovaries * Has regular menstrual cycles of 25-35 days duration * Able to comply with the protocol, including frequent blood sampling, and lives within the catchment area of the clinic * Understands the study procedures and agrees to participate in the study by giving written informed consent * Able to use non-hormonal, double-barrier contraceptives (e.g. condoms and diaphragm) with every act of intercourse, or has been sterilized with tubal ligation, or only male partner has been sterilized with vasectomy * Progesterone \>10 nmol/L in at least one sample in the lead-in cycle Exclusion Criteria: * All contraindications to OC use including * Thrombophlebitis or thromboembolic disorders * Past history of deep vein thrombophlebitis or thromboembolic disorders * Past or current cerebrovascular or coronary artery disease * Known or suspected carcinoma of the breast * Carcinoma of the endometrium or other known or suspected estrogen-dependent neoplasia * Undiagnosed abnormal genital bleeding * Cholestatic jaundice of pregnancy or jaundice with prior pill use * Hepatic adenomas or carcinomas * Woman has a history of headaches with focal neurological symptoms * Known or suspected pregnancy * Aged \>35 and smoker * BMI \>29 * Positive urine pregnancy test at the screening or baseline visit * Desired pregnancy within the duration of the study * Known hypersensitivity to progestins * Known hypersensitivity to estrogen * Undiagnosed vaginal discharge or vaginal lesions or abnormalities * In accordance with the Bethesda system of classification Women with a current abnormal Pap smear suggestive of high-grade pre cancerous lesion(s), including HGSIL, are excluded * Women with LGSIL or ASCUS/high-risk HPV positive may participate if further evaluated with colposcopy and biopsy and no evidence of a lesion with a severity \>CIN I is present and/or endocervical curettage is negative * Women with a biopsy finding of CIN I should have follow up for this finding per standard of care; women are excluded if treatment is indicated In accordance with other Pap class systems * Women with high grade dysplasia are excluded * Women with low grade dysplasia or CIN I interpretation on Pap smear may participate based on investigator discretion in accordance with local standard of care * Breastfeeding * Cancer (past history of any carcinoma or sarcoma) * History of a significant psychiatric disorder, including severe depression. * Chronic or acute liver or renal disease * Hypertension-- controlled by medication or defined by diastolic BP 85 mm Hg or systolic BP 135mm Hg after 15 minutes rest * Dermatitis, psoriasis or other severe skin disorder * Known or suspected alcoholism or drug abuse * Clinically significant abnormalities of laboratory safety tests * Chronic disease or history of illness that, in the opinion of the investigator, might confound the results of the study or pose additional risk to the subject * Woman is participating or has participated in another clinical study (involving an investigational drug) within one month prior to enrollment. * Use of injectable contraceptives during the previous 3 months (e.g. cyclofem) or 9 months (e.g. DMPA) * Use of oral contraceptives within the past 1 month * Use of concomitant drugs that may interact with the study drugs