Increasing serum 25-hydroxyvitamin D is associated with reduced odds of long menstrual cycles in a cross-sectional study of African American women

Fertil Steril. 2016 Jul;106(1):172-179.e2. doi: 10.1016/j.fertnstert.2016.03.004. Epub 2016 Mar 18.


Objective: To examine the association between serum 25-hydroxyvitamin D [25(OH)D] and menstrual cycle length and regularity.

Design: 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.

Setting: Not applicable.

Patient(s): A total of 1,102 African American women.

Intervention(s): Not applicable.

Main outcome measure(s): 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."

Result(s): 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.

Conclusion(s): 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.

Keywords: Ovarian function; PCOS; ovulation; vitamin D.

MeSH terms

  • Adult
  • Biomarkers / blood
  • Black or African American*
  • Cross-Sectional Studies
  • Female
  • Humans
  • Logistic Models
  • Menstrual Cycle / blood
  • Menstrual Cycle / ethnology*
  • Menstruation Disturbances / blood
  • Menstruation Disturbances / diagnosis
  • Menstruation Disturbances / ethnology*
  • Menstruation Disturbances / physiopathology
  • Michigan
  • Odds Ratio
  • Ovary / physiopathology
  • Ovulation
  • Risk Factors
  • Seasons
  • Time Factors
  • Up-Regulation
  • Vitamin D / analogs & derivatives*
  • Vitamin D / blood
  • Vitamin D Deficiency / blood
  • Vitamin D Deficiency / diagnosis
  • Vitamin D Deficiency / ethnology*
  • Young Adult


  • Biomarkers
  • Vitamin D
  • 25-hydroxyvitamin D