Bleeding patterns with progestin-containing IUDs vary according to the LNG dose
Goldthwaite LM, Creinin MD. Comparing bleeding patterns for the levonorgestrel 52 mg, 19.5 mg, and 13.5 mg intrauterine systems. Contraception. 2019;100:128-131.
Counseling on IUDs' different hormonal doses requires an understanding of patients' desires for contraceptive efficacy and bleeding expectations. A recent study provides guidance on what patients typically can expect for their bleeding patterns over the first few years with the 3 different doses of LNG IUDs.
Goldthwaite and Creinin used existing published or publicly available data to analyze differences in bleeding patterns associated with the 52-mg, 19.5-mg, and 13.5-mg LNG IUDs. Although two 52-mg LNG IUDs are available, published data using the WHO Belsey criteria are available only for one (Liletta; Allergan, Medicines360). The 2 products have been shown previously to have similar drug-release rates and LNG levels over 5 years.8
Comparing favorable bleeding patterns: Amenorrhea and infrequent bleeding
Among favorable bleeding patterns, amenorrhea was uncommon in the first 90 days and increased over time for all 3 IUDs. However, starting as soon as the second 90-day reference period, amenorrhea rates were significantly higher with the 52-mg LNG IUD compared with both of the lower-LNG dose IUDs, and this difference increased through 3 years of use (FIGURE 1).
Similarly, the 19.5-mg LNG IUD users had significantly higher rates of amenorrhea than the 13.5-mg LNG IUD users for all periods starting with the second 90-day reference period. At 3 years, 36% of women using the 52-mg LNG IUD had amenorrhea compared with 20% of those using the 19.5-mg LNG IUD (P<.0001) and 12% of those using the 13.5-mg LNG IUD (P<.0001).
Infrequent bleeding was similar for all 3 LNG IUDs in the first 90-day period, and it then increased most rapidly in the 52-mg LNG IUD users. At the end of year 1, 30% of the 52-mg LNG IUD users had infrequent bleeding compared with 26% of the 19.5-mg users (P = .01) and 20% of the 13.5-mg users (P<.0001). Although there was no difference in infrequent bleeding rates between the 52-mg and the 19.5-mg LNG IUD users at the end of year 1, those using a 52-mg LNG IUD had significantly higher rates of infrequent bleeding compared with the 13.5-mg LNG IUD at all time points.
Comparing unfavorable bleeding patterns: Frequent, prolonged, and irregular bleeding
Frequent and prolonged bleeding were uncommon with all LNG doses. Irregular bleeding rates declined for users of the 3 IUDs over time. However, significantly fewer users of the 52-mg LNG IUD reported irregular bleeding at 1 year (6%) compared with users of the 19.5-mg (16.5%, P<.0001) and 13.5-mg (23%, P<.0001) LNG IUD (FIGURE 2).
Study limitations
Comparing the data from different studies has limitations. For example, the data were collected from different populations, with the lower-dose LNG products tested in women who had a lower body mass index (BMI) and higher parity. However, prior analysis of the data on the 52-mg LNG IUD demonstrated that bleeding pattern changes did not vary based on these factors.10
WHAT THIS EVIDENCE MEANS FOR PRACTICE
When considering the different progestin-based IUD options, it is important to counsel patients according to their preferences for potential adverse effects. A randomized trial during product development found no difference in systemic adverse effects with the 3 doses of LNG IUD, likely because the systemic hormone levels are incredibly low for all 3 products.11 The summary data in this report helps explain why women using the lower-dose LNG products have slightly higher discontinuation rates for bleeding complaints, a fact we can explain to our patients during counseling.
Overall, the 52-mg LNG IUD is associated with a higher likelihood of favorable bleeding patterns over the first few years of use, with higher rates of amenorrhea and infrequent bleeding and lower rates of irregular bleeding. For women who prefer to not have periods or to have infrequent periods, the 52-mg LNG IUD is most likely to provide that outcome. For a patient who prefers to have periods, there is no evidence that the lower-dose IUDs result in “regular” or “normal” menstrual bleeding, even though they do result in more bleeding/spotting days overall. To the contrary, the available data show that these women have a significantly higher likelihood of experiencing prolonged, frequent, and irregular bleeding. In fact, no studies have reported rates of “normal” bleeding with the progestin IUDs, likely because women uncommonly have “normal” bleeding with these contraception methods. If a patient does not desire amenorrhea or strongly prefers to have “regular bleeding,” alternative methods such as a copper IUD should be considered rather than counseling her toward a lower-dose progestin IUD.
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