Effect of levonorgestrel-releasing intrauterine device on hormonal profile and menstrual pattern after long-term use.
Level 4 - case-series / case-control
Prospective case series without a control group
PubMed 7554977 · doi:10.1016/0010-7824(95)00102-g
What was done
Fourteen women in China who had used a 20 mcg/day levonorgestrel-releasing intrauterine device (LNG-IUD) for 6 years were evaluated over a 26- to 40-day observation period. Serum concentrations of luteinizing hormone (LH), progesterone, estradiol, prolactin, sex hormone-binding globulin (SHBG), and levonorgestrel were measured from blood samples collected three times weekly. Follicular development was tracked with serial ultrasound scans, and participants recorded bleeding and spotting with menstrual diary cards.
What was found
Ovulatory cycles were detected in 11 of 14 women (78.5%), including 5 with normal cycles, 4 with prolonged or irregular cycles, and 2 with amenorrhea for 2 to 3 years. One woman had luteal phase insufficiency, and 2 women had anovulatory cycles with follicular hyperactivity (total anovulatory rate: 14.3%). Persistent follicle enlargement on ultrasound coincided with elevated estradiol. Mean serum levonorgestrel levels at 6 years remained detectable and were significantly lower in ovulatory women than in anovulatory women (314.26 vs. 470.63 pmol/L, p < 0.001).
Why it matters
These findings show that systemic ovarian function and ovulation are largely maintained after 6 years of LNG-IUD use, supporting the concept that contraception relies primarily on local endometrial effects rather than chronic ovulatory suppression.
Limits
The study is an uncontrolled case series with a very small sample size (n = 14) monitored over a single short window (26 to 40 days). The abstract does not provide numeric comparison data from the first year of use despite stating this as an aim.
Cited by
- supports A levonorgestrel-releasing (progesterone) intrauterine device typically suppresses ovulation during the first two years of use, after which progesterone levels decline and ovulation typically resumes.