The levonorgestrel-releasing implant is highly effective and generally safe, but is associated with higher risks of some health problems than are other, nonsteroidal contraceptive methods, according to a cohort study of women in eight developing countries.¹ Compared with women who relied on sterilization or the IUD, women who used the implant were more likely to have gallbladder disease (rate ratio, 1.5) or high blood pressure (1.8). The risk of inflammatory disease of the genital tract, however, was significantly lower in implant users (0.3) than in women relying on either of the other two methods.

The study was conducted in 32 family planning clinics located in Bangladesh, Chile, China, Columbia, Egypt, Indonesia, Sri Lanka and Thailand. Women seeking contraceptive services who were aged 20-40 years and had no contraindications to the hormonal implant, the IUD or sterilization were eligible to enroll. Those who agreed to participate were instructed to visit the clinic six weeks after enrollment and then semiannually for the next five years. For each woman who chose the implant, the researchers selected a woman who was initiating the use of either an IUD or sterilization and was within the same five-year age-group.

At the initial clinic visit, each subject received breast and pelvic examinations, a Pap smear, and blood pressure and hemoglobin measurements. During subsequent visits, the women received further testing and diagnostic procedures when medically indicated, and all complaints, symptoms and diseases were recorded.

In total, 16,021 women were enrolled in the study: 7,977 who chose the implant, 6,625 the IUD and 1,419 sterilization. After five years, 95% of the women continued to participate in the study, and 84-100% were still using the contraceptive method they had initially selected. A larger proportion of women using the implant (85%) than women relying on the IUD (76%) or sterilization (75%) had ever previously practiced contraception; 38% of implant users had used oral contraceptives, while only 28% of IUD users and 27% of sterilized women had done so.

During the five years of the study, implant users, IUD users and women who had been sterilized all had annual pregnancy rates of less than one per 100 woman-years; ectopic pregnancy rates were lower than one per 1,000 woman-years. Thirty-four participants died during the study period; 22 deaths were due to accidents, suicide or homicide. Neither the overall mortality rate nor the mortality rate for specific diseases (both of which were adjusted for clinic) was significantly greater for implant users compared with those for the other two groups.

Compared with women relying on the IUD or sterilization, implant users had an elevated risk of gall bladder disease and high blood pressure (rate ratios of 1.5 and 1.8, respectively), the only major conditions for which a significant difference was found. However, implant users had an elevated risk for several other health problems--respiratory diseases (1.8-3.2), mental disorders (primarily anxiety and depression, 2.7), and unspecified disorders of the breast (1.7) and central nervous system (primarily migraine, 2.5). Implant users also experienced significantly higher rates of certain less serious symptoms, the most common of which were dizziness, malaise and fatigue, weight loss, weight gain and headache. The risk of acute pelvic infection was significantly lower for implant users than for women using the other two methods (0.3).

The researchers comment that although implant users showed "a pronounced tendency" toward higher rates of less serious health problems, there was little evidence of increased risks of life-threatening conditions. They note that increased surveillance and monitoring of implant users compared with those using the other two contraceptive methods may have contributed to the elevated reporting rates. Apart from a weak association with gallbladder disease and hypertension, the researchers conclude that the implant is "not associated with any material risk of major morbidity compared with IUDs and female sterilization." --J. Rosenberg

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