Patterns of ovulation and bleeding with a low levonorgestrel-releasing intrauterine device.

Patterns of bleeding and plasma concentrations of levonorgestrel, progesterone, estradiol, LH and FSH were studied in ten volunteers who had a levonorgestrel-releasing IUD inserted postmenstrually. The IUD was designed to release 12 microgram/day. All but two of the volunteers ovulated during treatment. The ovulatory cycles differed from the control cycles by being longer and by having depressed plasma progesterone levels during the luteal phases. Intermenstrual spottings occurred frequently during the first sixty days of treatment. No pregnancies occurred during the course of the study.