A comparison of the inhibition of ovulation achieved by desogestrel 75 mu g and levonorgestrel 30 mu g daily

A randomized, double blind, group comparative study was performed over a 12 month period to compare inhibition of ovulation during the use of two (pro gestogen-only) oral contraceptives containing doses of 75 mu g desogestrel or 30 mu g levonorgestrel. Seventy-one female volunteers with regular cycle s and established ovulation by ultrasonography and serum progesterone conce ntrations were recruited from an out-patient clinic in a university hospita l and asked to participate in the study. Transvaginal ultrasonography and s erum oestradiol, progesterone, luteinizing hormone (LH) and follicle stimul ating hormone (FSH) measurements were performed throughout the 7th and 12th 28 day treatment period. Desogestrel at a dose of 75 mu g showed a signifi cant inhibition of ovulation compared to 30 mu g levonorgestrel (P < 0.001) .