title: A single-arm study to evaluate the efficacy, safety and acceptability of pericoital oral contraception with levonorgestrel.
abstract: BACKGROUND
  An oral dose of 0.75 mg levonorgestrel (LNG) taken shortly after sex was marketed as a routine, nonemergency contraceptive method until the 1990s. Because a hormonal method used only at the time of intercourse may be desirable for women who have infrequent sex, we conducted a study to reevaluate the potential of pericoital LNG as a primary means of contraception.
  
  
  METHODS
  We enrolled women aged 18-45 years in Brazil and the USA who expected to have sex 1-4 days per month for 6.5 months. Participants were instructed to take one tablet 0.75 mg LNG within 24 h before or after sex, with no more than one dose in any 24-h period. The primary efficacy measure was the Pearl Index among women aged 18-35 years.
  
  
  RESULTS
  The study was stopped after 72 of the planned 300 participants were enrolled due to slow recruitment and related feasibility considerations. In the primary analysis, three pregnancies occurred during 13.4 woman-years of follow-up, resulting in a Pearl Index of 22.4 (95% confidence interval, 4.6-65.4). No serious adverse events were reported, and vaginal bleeding patterns were generally acceptable.
  
  
  CONCLUSIONS
  Our estimated Pearl Index was noticeably higher than expected from previous research of LNG for pericoital contraception. Although the regimen was safe and generally acceptable, the study was challenged by slow enrollment and curtailed person-years of follow-up, resulting in poor precision for the estimated treatment effect. Future research may inform whether our results are symptomatic of the regimen, study design or characteristics of the populations from which we recruited.
  
  
  CONCLUSIONS
  Our study failed to confirm prior data suggesting that 0.75 mg LNG for pericoital contraception could be more effective than typical use of barrier methods among women having infrequent sex. Characterizing populations most likely to adhere to, and benefit from, pericoital regimens is essential to future research on these methods.
authors.affiliation: FHI 360, 2224 E NC HWY 54, Durham, NC 27713, USA.
authors.forename: Douglas J
authors.initials: DJ
authors.lastname: Taylor
authors.affiliation: FHI 360, 2224 E NC HWY 54, Durham, NC 27713, USA.
authors.forename: Anja
authors.initials: A
authors.lastname: Lendvay
authors.affiliation: FHI 360, 2224 E NC HWY 54, Durham, NC 27713, USA. Electronic address: vhalpern@fhi360.org.
authors.forename: Vera
authors.initials: V
authors.lastname: Halpern
authors.affiliation: Human Reproductive Unit, Department of Obstetrics and Gynecology, School of Medicine, University of Campinas, Campinas, Brazil.
authors.forename: Luis G
authors.initials: LG
authors.lastname: Bahamondes
authors.affiliation: Planned Parenthood Gulf Coast, Inc. , 4600 Gulf Freeway Houston, TX 77023-3533, USA.
authors.forename: Paul M
authors.initials: PM
authors.lastname: Fine
authors.affiliation: Planned Parenthood of the Rocky Mountains, Denver, CO 80207, USA.
authors.forename: Savita Y
authors.initials: SY
authors.lastname: Ginde
authors.affiliation: FHI 360, 2224 E NC HWY 54, Durham, NC 27713, USA.
authors.forename: Angie
authors.initials: A
authors.lastname: Wheeless
authors.affiliation: Gynuity Health Projects, New York, NY 10010, USA.
authors.forename: Elizabeth G
authors.initials: EG
authors.lastname: Raymond
mesh_terms: D000293:Adolescent; D000328:Adult; D001938:Brazil; D003075:Coitus; D044363:Contraception, Postcoital; D003271:Contraceptive Agents, Female / Q000008:administration & dosage* / Q000009:adverse effects; D005260:Female; D006801:Humans; D016912:Levonorgestrel / Q000008:administration & dosage* / Q000009:adverse effects; D008875:Middle Aged; D011247:Pregnancy; D011446:Prospective Studies; D014481:United States; D055815:Young Adult
chemical_list: D003271:Contraceptive Agents, Female; D016912:Levonorgestrel
keywords: Levonorgestrel; Pericoital oral contraception; Single-arm study