title: Menstrual cycle characteristics and fecundability in a North American preconception cohort.
abstract: The aim of this study was to evaluate the association between menstrual cycle characteristics in early life and adulthood and fecundability.
  
  
  
  Pregnancy Study Online (PRESTO) is an Internet-based preconception cohort study of pregnancy planners from the United States and Canada. During the preconception period, we enrolled 2189 female pregnancy planners aged 21-45 years who had been attempting conception for ≤6 cycles. Women self-reported menstrual cycle characteristics via an online baseline questionnaire, and pregnancy status was ascertained through bimonthly follow-up questionnaires. Proportional probabilities models were used to estimate fecundability ratios (FRs) and 95% confidence intervals (CIs), adjusting for potential confounders.
  
  
  
  Compared with usual menstrual cycle lengths of 27-29 days, cycle lengths of <25 (FR = 0.81, 95% CI: 0.54-1.22) and 25-26 days (FR = 0.92, 95% CI: 0.75-1.14) were associated with reduced fecundability. Compared with women who reached menarche at the age of 12-13 years, those who reached menarche at <12 years had reduced fecundability (FR = 0.87, 95% CI: 0.76-0.99). Women whose cycles never regularized after menarche (FR = 0.93, 95% CI: 0.81-1.06) had slightly reduced fecundability compared with women whose cycles regularized within 2 years of menarche. Bleed length and heaviness of bleeding were not appreciably associated with fecundability.
  
  
  
  Menstrual cycle characteristics, specifically cycle length and age at menarche, may act as markers of fertility potential among pregnancy planners.
authors.affiliation: Department of Epidemiology, Boston University School of Public Health, Boston, MA. Electronic address: akw23@bu.edu.
authors.forename: Amelia K
authors.initials: AK
authors.lastname: Wesselink
authors.affiliation: Department of Epidemiology, Boston University School of Public Health, Boston, MA; Slone Epidemiology Center, Boston University School of Public Health, Boston, MA.
authors.forename: Lauren A
authors.initials: LA
authors.lastname: Wise
authors.affiliation: Department of Epidemiology, Boston University School of Public Health, Boston, MA.
authors.forename: Elizabeth E
authors.initials: EE
authors.lastname: Hatch
authors.affiliation: Department of Epidemiology, Boston University School of Public Health, Boston, MA; RTI Health Solutions, Research Triangle Park, NC.
authors.forename: Kenneth J
authors.initials: KJ
authors.lastname: Rothman
authors.affiliation: Department of Clinical Epidemiology, Aarhus University Hospital, Aarhus, Denmark.
authors.forename: Ellen M
authors.initials: EM
authors.lastname: Mikkelsen
authors.affiliation: Department of Family and Preventive Medicine, University of Utah, Salt Lake City, UT.
authors.forename: Joseph B
authors.initials: JB
authors.lastname: Stanford
authors.affiliation: Department of Epidemiology, Boston University School of Public Health, Boston, MA.
authors.forename: Craig J
authors.initials: CJ
authors.lastname: McKinnon
authors.affiliation: Department of Obstetrics & Gynecology, Boston University Medical Center, Boston, MA.
authors.forename: Shruthi
authors.initials: S
authors.lastname: Mahalingaiah
mesh_terms: D000293:Adolescent; D000328:Adult; D000367:Age Factors; D002170:Canada; D002648:Child; D015331:Cohort Studies; D003430:Cross-Sectional Studies; D005260:Female; D005298:Fertility / Q000502:physiology*; D006801:Humans; D008597:Menstrual Cycle / Q000502:physiology*; D008875:Middle Aged; D009656:North America; D016742:Preconception Care; D011247:Pregnancy; D018873:Pregnancy Rate; D012044:Regression Analysis; D015203:Reproducibility of Results; D011795:Surveys and Questionnaires; D014481:United States; D055815:Young Adult
keywords: Fecundability; Menstrual cycle; Preconception cohort; Time-to-pregnancy