Retrospective vs. prospective coital frequency and menstrual cycle length in a contraceptive effectiveness trial

Markus J. Steiner, Irva Hertz-Picciotto, Doug Taylor, Victor Schoenbach, Angie Wheeless

Research output: Contribution to journalArticle

16 Scopus citations


PURPOSE: To determine how well information at enrollment would predict coital frequency and menstrual segment length during a prospective contraceptive effectiveness trial. METHODS: We compared retrospective reports of monthly coital frequency and menstrual segment (cycle) length with prospective information for women participating in a contraceptive trial of the Reality® female condom. RESULTS: Participants reported slightly higher mean monthly coital frequency and slightly longer menstrual segments prior to the study than during the study (12.6 acts vs. 12.0 acts per month and 30.8 days vs. 28.4 days). We examined the actual distribution of differences between the retrospective and prospective measures and found considerable variability. Among the 195 participants studied, parous women were less likely to predict accurately menstrual segment length (OR 0.4; 95% CI 0.3-0.9), while older women were more likely to predict accurately coital frequency (OR 1.9; 95% CI 0.9-3.3). CONCLUSIONS: Coital frequency and menstrual segment length vary considerably over time. Hence, prospective data collection is essential to accurately characterize these variations and to properly interpret results from contraceptive trials and other studies concerned with fecundability and hazards of reproduction.

Original languageEnglish (US)
Pages (from-to)428-433
Number of pages6
JournalAnnals of Epidemiology
Issue number6
StatePublished - 2001
Externally publishedYes



  • Coitus
  • Contraception Behavior
  • Family Planning
  • Female Condoms
  • Menstrual Cycle

ASJC Scopus subject areas

  • Medicine(all)
  • Public Health, Environmental and Occupational Health
  • Epidemiology

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