Effectiveness of Norplant implants among Thai women in Bangkok.

ABSTRACT

PIP: Between June 1986 and December 1988, staff at a family planning clinic in greater Bangkok, Thailand, recruited 308 healthy women aged 18-45 for a clinical trial designed to evaluate the efficacy, acceptability, side effects, and continuation rates of the contraceptive implant system Norplant. Their average parity was 1.9 live births. The cumulative first-, second-, third-, fourth-, and fifth-year continuation rates stood at 97.6%, 90.7%, 82.9%, 77.9%, and 71%, respectively. During the first two years, no Norplant acceptor became pregnant. In the third year, however, the cumulative accidental pregnancy rate was 1.1% and increased to 2% in the fourth year and 4.2% in the fifth year. All accidental pregnancies were intrauterine. The major reason for Norplant removal was desire for pregnancy (5-year cumulative termination rate = 9.2%) followed by changes in menstruation patterns, particularly increased menstrual bleeding (4.4%). The prevalence of menstruation disorders decreased with time, however. For example, 64.8% of all users experienced an irregular menstrual cycle during the first 1-3 months of Norplant use. By 22-24 months of use, it had fallen to 54.9%, and to 39.5% by 58-60 months of use. The five-year cumulative termination rate for other personal reasons was 7.9%. These reasons included husband undergoing vasectomy, husband's objection to Norplant, and divorce. The relatively high continuation rates at the first and fifth year of use suggest that Thai women accepted Norplant well. The higher accidental pregnancy rates at four and five years of use than those of other international studies are troublesome, however.