title: Menstrual bleeding patterns following levonorgestrel emergency contraception.
abstract: OBJECTIVE
  Multiple trials by the World Health Organization have established levonorgestrel as the gold standard in hormonal emergency contraception (EC). However, changes in menstrual patterns following EC have been observed; thus, we undertook this prospective study to identify and determine the characteristics of these changes.
  
  
  METHODS
  Women requesting EC at either any of two hospitals --1 family planning unit and 12 pharmacies in Yaoundé, Cameroon were enrolled if they had a history of regular menstrual cycles over the previous 3 months and if they agreed to follow-up until the end of the subsequent menstrual cycle. Pretreatment menstrual patterns were compared with those of the EC treatment cycle and the cycle after EC.
  
  
  RESULTS
  In a set of 232 participants (mean age, 25 years), we observed 34 (14.7%) cases of incident intermenstrual bleeding and statistically significant changes in menstrual cycle length, menstrual period length and menstrual appearance compared to baseline patterns that differed according to whether EC was taken well before, close to or well after the expected ovulation for that cycle. The majority of these changes disappeared in the following cycle.
  
  
  CONCLUSIONS
  Levonorgestrel EC is associated with significant but transient changes in menstrual patterns in a significant proportion of users.
authors.affiliation: INSERM, U569, Epidemiology, Demography and Social Sciences, IFR69, Le Kremlin-Bicêtre 94276, France. e.gainer@hra-pharma.com
authors.forename: Erin
authors.initials: E
authors.lastname: Gainer
authors.forename: Bruno
authors.initials: B
authors.lastname: Kenfack
authors.forename: Emile
authors.initials: E
authors.lastname: Mboudou
authors.forename: Anderson Sama
authors.initials: AS
authors.lastname: Doh
authors.forename: Jean
authors.initials: J
authors.lastname: Bouyer
mesh_terms: D000293:Adolescent; D000328:Adult; D003281:Contraceptives, Postcoital / Q000008:administration & dosage*; D005260:Female; D006801:Humans; D016912:Levonorgestrel / Q000008:administration & dosage*; D008597:Menstrual Cycle / Q000187:drug effects; D008598:Menstruation / Q000187:drug effects*; D011446:Prospective Studies; D012044:Regression Analysis; D013997:Time Factors; D014592:Uterine Hemorrhage / Q000453:epidemiology
chemical_list: D003281:Contraceptives, Postcoital; D016912:Levonorgestrel