Endometrial microstructure after long-term use of a 91-day extended-cycle oral contraceptive regimen.

Objective: To assess the effect on the endometrial microstructure of an extended-cycle oral contraceptive (OC) regimen containing ethinyl estradiol (EE) and levonorgestrel (LNG).

Methodology: Subjects received up to four cycles of a 91-day extended-cycle OC regimen (84 consecutive days of monophasic 30 microg EE/150 microg LNG followed by 7 days of placebo). Endometrial biopsies were performed prior to the initiation and at the completion of therapy.