Effectiveness of Norplant implants among Thai women in Bangkok.

The purpose of the study was to evaluate the efficacy, acceptability, side effects and continuation rates of the implant system in Thai women. A five-year clinical study of 308 women receiving Norplant-6 implants in Bangkok was conducted. Acceptors' mean age was 29 years, and mean number of children was about two. More than half of the users (63%) finished primary school. The cumulative continuation rates for Norplant implants at first, second, third, fourth and fifth years were, respectively, 98%, 91%, 83%, 78% and 71%. Eight out of a total of eleven pregnancies occurred in the fourth and fifth year of use. The cumulative pregnancy rate was 1.1% for the third year, 2.0% for the fourth year and 4.2% for the fifth year. Desire for future pregnancy was the leading cause for termination of Norplant implants use. The five-year cumulative termination rate for planned pregnancy was 9.2%. Disruption of menstrual rhythm, particularly increased bleeding, was the other main reason for termination; however, the prevalence of menstrual irregularities appeared to diminish with time. The cumulative termination rate for menstrual irregularities in the fifth year of the study was 4.4%. The complaints of "other medical reasons" for removal of Norplant implants were acne, severe headache, and chloasma. The five-year cumulative termination rate for other personal reasons was 7.9%. These personal reasons were husband having vasectomy, husband objection and divorce. It can be seen from this five-year study that Norplant implants are well accepted by Thai women. However, the efficacy in preventing pregnancy was not acceptable during the fourth and fifth year of use in this study, which was different from results of other international studies.