The purpose of this study was to examine the bleeding patterns of 234 Norplant users during 5 years of use and to identify the bleeding patterns of users who conceived. During the first year of use, 26.6% of users had regular bleeding cycles, 66.3% had irregular cycles, and 7.1% were amenorrheic. By the fifth year of use, 62.5% of users had regular cycles, 37.5% had irregular cycles, and none had amenorrhea. Of the ten users who became pregnant, eight had regular menstrual cycles in the 6 months before the diagnosis of pregnancy, one had an irregular pattern, and one did not keep a bleeding record. None had amenorrhea. The 5-year cumulative pregnancy rate for patients with regular cycles was 17.4%; this was significantly higher (P<.05) than the 5-year cumulative rates of 4.4% in users with irregular cycles and 0% in users with amenorrhea. This study indicates that during the first year of Norplant use, only 26.6% of users have regular cycles, but after the first year, 50-60% of users develop regular cycles. The bleeding patterns of women using Norplant improve after the first year of use, and those with regular cycles are at greatest risk for method failure.
(C) 1991 The American College of Obstetricians and Gynecologists