title: A long-term study of the efficacy and acceptability of a single-rod hormonal contraceptive implant (Implanon) in healthy women in China.
abstract: OBJECTIVE
  To investigate the contraceptive efficacy, cycle control and acceptability of Implanon, a new single-rod, progestogen-only contraceptive implant.
  
  
  METHODS
  In a non-comparative, open, multicenter study, a contraceptive implant containing the progestogen etonogestrel was inserted into 200 healthy women. The study duration was 2 years, with an optional extension up to 4 years.
  
  
  RESULTS
  Women were exposed to Implanon for 644.6 woman-years. There were no pregnancies during the study. Per 90-day reference period, the median number of bleeding-spotting days ranged between 18 and 21 and the median number of bleeding-spotting episodes was two. The mean overall incidence of prolonged bleeding fell markedly during the study, from 69% in the first reference period to 26% in the 16th period. The most common adverse events were related to disturbed bleeding pattern and amenorrhea. Heavy or prolonged bleeding caused 18 subjects to withdraw from the study. Only a few subjects discontinued the study early due to irregular bleeding (2%) or amenorrhea (2%). A slight increase in mean body weight was observed. The implant was removed in an average time of 2.9 min.
  
  
  CONCLUSIONS
  Implanon demonstrated excellent contraceptive efficacy for 4 years of use and was well tolerated. The incidences of prolonged bleeding and amenorrhea both fell markedly with continued implant use. Because of its single-rod design, Implanon was quickly removed with few complications and proved to be a highly acceptable method of contraception.
authors.affiliation: Department of Obstetrics and Gynecology, First Teaching Hospital, Beijing Medical College, China.
authors.forename: S R
authors.initials: SR
authors.lastname: Zheng
authors.forename: H M
authors.initials: HM
authors.lastname: Zheng
authors.forename: S Z
authors.initials: SZ
authors.lastname: Qian
authors.forename: G W
authors.initials: GW
authors.lastname: Sang
authors.forename: R F
authors.initials: RF
authors.lastname: Kaper
mesh_terms: D000328:Adult; D002681:China / Q000453:epidemiology; D003271:Contraceptive Agents, Female / Q000008:administration & dosage / Q000494:pharmacology*; D017135:Desogestrel; D004343:Drug Implants; D005260:Female; D006801:Humans; D015994:Incidence; D008137:Longitudinal Studies; D008597:Menstrual Cycle / Q000187:drug effects*; D045167:Progesterone Congeners / Q000008:administration & dosage / Q000494:pharmacology*; D014592:Uterine Hemorrhage / Q000453:epidemiology; D014753:Vinyl Compounds / Q000008:administration & dosage / Q000494:pharmacology*
chemical_list: D003271:Contraceptive Agents, Female; D004343:Drug Implants; D045167:Progesterone Congeners; D014753:Vinyl Compounds; C044815:etonogestrel; D017135:Desogestrel