An intrauterine device (IUD) is a highly effective contraceptive method. Research is ongoing for hormonal and non-hormonal methods to determine safety and effectiveness. An international research team headed by the Los Angeles Biomedical Research Institute, Harbor-UCLA Medical Center (Torrance, California) conducted clinical trials on two low-dose two low-dose levonorgestrel intrauterine contraceptive systems. They reported their findings in the December 2013 edition of the journal Obstetrics & Gynecology.
The researchers note that the currently available levonorgestrel intrauterine contraceptive system, which was introduced in the US in 2001, contains 52 mg levonorgestrel. Since its introduction, it has increased in popularity because of its safety, convenience, and effectiveness. The contraceptive also decreases menstrual flow in women who suffer from heavy menses. Despite those facts, the researchers found that many physicians to not insert the device in women who have not borne a child (nulliparous women). They cite a recent survey that found that more than 60% of US physicians only infrequently offer intrauterine contraceptives to these women. In addition, a recent study conducted at US community family planning clinics noted that 19% of attempts at intrauterine contraceptive placement in nulliparous women were unsuccessful.
The researchers note that lower-dose levonorgestrel IUDs have been developed; one contains 13.5 mg levonorgestrel and the other contains 19.5 mg levonorgestrel. These IUDs have smaller reservoirs of levonorgestrel and smaller T-frames, which allow placement using a narrower tube than the existing 52 mg product. Thus, the investigators proposed that these lower-dose IUDs may be suitable for women with a narrower cervical canal, a smaller uterine cavity, or both. Therefore, they conducted a three year, prospective (forward-looking) clinical trial of those two IUDs They evaluated the following factors: pregnancy rates; bleeding patterns; ease and pain of placement, safety; continuation rates; and user satisfaction.
The study included nulliparous women and parous women (women who had borne one or more children) aged 18−35 years with regular menstrual cycles (21−35 days) who were desirous of contraception. The women were randomized to three years of treatment with one of two levonorgestrel intrauterine contraceptive systems: 13.5 mg levonorgestrel (1,432 women) or 19.5 mg levonorgestrel (1,452 women). IUD placement was attempted in all the women. The average age of the women was 27.1 years and 39.2% were nulliparous. Over the 3-year study period, 0.33 pregnancies per 100 women-years occurred the 13.5 mg IUD, compared with 0.31 per 100 women-years with the 19.5 mg IUD. At least partial expulsions occurred in 4.56% of the nulliparous women and 3.58% of the parous women; discontinuation rates resulting from a reported adverse event occurred in 21.9% of the nulliparous women and 19.1% of the parous women. Ten of the 20 pregnancies were ectopic (tubal pregnancies). Serious adverse events included six cases of pelvic inflammatory disease and one partial uterine perforation.
The authors concluded that both lower-dose levonorgestrel IUDs were highly effective for three years of use and generally well tolerated.
Take home message:
This study found that the low-dose levonorgestrel IUSs were effective and well-tolerated regardless of whether the woman had borne a child. The IUD has a distinct advantage over many other contraceptive methods in that it does not require taking a daily pill or other preparation before intercourse. If a woman has an IUD in place and is exposed to a sexually transmitted disease (STD), the presence of the device may increase the risk of a higher degree of infection; thus, it may not be the best method for a women who has more than one partner (the greater the number of partners, the greater the risk of exposure to an STD.