title: Increasing serum 25-hydroxyvitamin D is associated with reduced odds of long menstrual cycles in a cross-sectional study of African American women.
abstract: To examine the association between serum 25-hydroxyvitamin D [25(OH)D] and menstrual cycle length and regularity.
  
  
  
  Community-based, cross-sectional study of serum 25(OH)D (adjusted for seasonal differences in timing of blood draw) and menstrual cycle length. Women aged 23-34 years reported their gynecologic history. Menstrual cycles were described with four independent categories (normal, short, long, irregular). We used polytomous logistic regression to estimate the association between a doubling of seasonally adjusted 25(OH)D and the odds of each cycle category.
  
  
  
  Not applicable.
  
  
  
  A total of 1,102 African American women.
  
  
  
  Not applicable.
  
  
  
  Self-reported menstrual cycle length over the previous 12 months, excluding women who were using cycle-regulating medications over the entire year. Women who reported that their cycles were "too irregular to estimate" were classified as having irregular cycles. A typical cycle length of <27 days was considered "short," >34 days was "long," and 27-34 days was "normal."
  
  
  
  The median 25(OH)D level was 14.7 ng/mL (interquartile range, 10.9-19.6 ng/mL). A doubling of 25(OH)D was associated with half the odds of having long menstrual cycles: adjusted odds ratio (aOR) 0.54, 95% confidence interval (CI) 0.32-0.89. 25-Hydroxyvitamin D was not associated with the occurrence of short (aOR 1.03, 95% CI 0.82-1.29) or irregular (aOR 1.46, 95% CI 0.88-2.41) menstrual cycles. Results were robust to several sensitivity analyses.
  
  
  
  These findings suggest that vitamin D status may influence the menstrual cycle and play a role in ovarian function. Further investigation of 25(OH)D and ovarian hormones, and prospective studies of 25(OH)D and cycle length, are needed.
authors.affiliation: Yale Center for Perinatal, Pediatric and Environmental Epidemiology, New Haven, Connecticut; Epidemiology Branch, National Institute of Environmental Health Sciences, Durham, North Carolina. Electronic address: annemarie.jukic@yale.edu.
authors.forename: Anne Marie Z
authors.initials: AMZ
authors.lastname: Jukic
authors.affiliation: Epidemiology Branch, National Institute of Environmental Health Sciences, Durham, North Carolina.
authors.forename: Kristen
authors.initials: K
authors.lastname: Upson
authors.affiliation: Epidemiology Branch, National Institute of Environmental Health Sciences, Durham, North Carolina.
authors.forename: Quaker E
authors.initials: QE
authors.lastname: Harmon
authors.affiliation: Epidemiology Branch, National Institute of Environmental Health Sciences, Durham, North Carolina.
authors.forename: Donna D
authors.initials: DD
authors.lastname: Baird
mesh_terms: D000328:Adult; D001741:Black or African American; D015415:Biomarkers / Q000097:blood; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D016015:Logistic Models; D008597:Menstrual Cycle / Q000097:blood / Q000208:ethnology*; D008599:Menstruation Disturbances / Q000097:blood / Q000175:diagnosis / Q000208:ethnology* / Q000503:physiopathology; D008824:Michigan; D016017:Odds Ratio; D010053:Ovary / Q000503:physiopathology; D010060:Ovulation; D012307:Risk Factors; D012621:Seasons; D013997:Time Factors; D015854:Up-Regulation; D014807:Vitamin D / Q000031:analogs & derivatives* / Q000097:blood; D014808:Vitamin D Deficiency / Q000097:blood / Q000175:diagnosis / Q000208:ethnology*; D055815:Young Adult
chemical_list: D015415:Biomarkers; D014807:Vitamin D; C104450:25-hydroxyvitamin D
keywords: Ovarian function; PCOS; ovulation; vitamin D