title: Telling truth from Ys: an evaluation of whether the accuracy of self-reported semen exposure assessed by a semen Y-chromosome biomarker predicts pregnancy in a longitudinal cohort study of pregnancy.
abstract: OBJECTIVE
  Adolescents may use condoms inconsistently or incorrectly, or may over-report condom use. This study used a semen exposure biomarker to evaluate the accuracy of female adolescents' reports of condom use and predict subsequent pregnancy.
  
  
  METHODS
  The sample comprised 715 sexually active African-American female adolescents, ages 15-21 years. At baseline, 6 months and 12 months, participants completed a 40-min interview and were tested for semen Y-chromosome with PCR from a self-administered vaginal swab. We predicted pregnancy from semen exposure under-report using multivariate regression controlling for oral contraception, reported condom use and coital frequency.
  
  
  RESULTS
  At the 3 surveys, 30%, 20% and 15% of adolescents who reported always using condoms tested positive for semen exposure. At 6 month follow-up, 20.4% and 16.2% of the adolescents who under-reported semen exposure reported pregnancy, a higher pregnancy rate than accurate reporters of semen exposure, even accurate reporters who reported never using condoms (14.2% and 11.8%). Under-reporters of semen exposure were 3.23 (95% CI (1.61, 6.45)) times as likely to become pregnant at 6-month follow-up and 2.21 (0.94, 5.20) times as likely to become pregnant at 12-month follow-up as accurate reporters who reported not using contraception, adjusting for self-reported coital frequency.
  
  
  CONCLUSIONS
  Adolescents who under-report semen exposure may be at uniquely high risk for unplanned pregnancy and STIs, and may also under-report coital frequency. Condom efficacy trials that rely on self-report may yield inaccurate results. Adapted to a clinical setting, the Y-chromosome PCR could alert women to incorrect or inconsistent condom use.
authors.affiliation: Department of Epidemiology and Biostatistics, School of Public Health, SUNY Downstate Medical Center, Brooklyn, New York, USA.
authors.forename: Janet E
authors.initials: JE
authors.lastname: Rosenbaum
authors.affiliation: Department of Infectious Diseases, Johns Hopkins Medical Institutions, Baltimore, Maryland, USA.
authors.forename: Jonathan
authors.initials: J
authors.lastname: Zenilman
authors.affiliation: Department of Infectious Diseases, Johns Hopkins Medical Institutions, Baltimore, Maryland, USA.
authors.forename: Johan
authors.initials: J
authors.lastname: Melendez
authors.affiliation: Behavioral Sciences and Health Education, Rollins School of Public Health, Emory University, Atlanta, Georgia, USA.
authors.forename: Eve
authors.initials: E
authors.lastname: Rose
authors.affiliation: Behavioral Sciences and Health Education, Rollins School of Public Health, Emory University, Atlanta, Georgia, USA.
authors.forename: Gina
authors.initials: G
authors.lastname: Wingood
authors.affiliation: Behavioral Sciences and Health Education, Rollins School of Public Health, Emory University, Atlanta, Georgia, USA.
authors.forename: Ralph
authors.initials: R
authors.lastname: DiClemente
mesh_terms: D000293:Adolescent; D000294:Adolescent Behavior; D001741:Black or African American / Q000706:statistics & numerical data*; D015415:Biomarkers; D041322:Chromosomes, Human, Y / Q000235:genetics; D015331:Cohort Studies; D017280:Condoms / Q000706:statistics & numerical data*; D005260:Female; D006801:Humans; D008137:Longitudinal Studies; D015999:Multivariate Analysis; D016133:Polymerase Chain Reaction; D011247:Pregnancy; D018873:Pregnancy Rate; D057566:Self Report; D012661:Semen; D014626:Vaginal Smears; D055815:Young Adult
chemical_list: D015415:Biomarkers
keywords: Adolescent; Condoms; Contraception; DNA Amplification; Pregnancy