Folic acid supplement use and menstrual cycle characteristics: a cross-sectional study of Danish pregnancy planners

Ann Epidemiol. 2015 Oct;25(10):723-9.e1. doi: 10.1016/j.annepidem.2015.05.008. Epub 2015 Jun 4.


Purpose: To examine the association between folic acid (FA) supplementation obtained through either single FA tablets or multivitamins (MVs) and menstrual cycle characteristics among 5386 women aged 18-40 years, enrolled in an Internet-based study of Danish women attempting pregnancy during 2007-2011.

Methods: In a cross-sectional study, we used logistic regression to estimate odds ratios (ORs) and 95% confidence intervals (CIs) for the associations of FA supplementation with menstrual cycle regularity; short (<27 days), long (30-33 days), and very long (≥34 days) cycle lengths; and duration and intensity of menstrual bleeding.

Results: Compared with nonuse, FA supplementation was associated with reduced odds of short cycle length (OR = 0.80, 95% CI: 0.68-0.94) and a trend toward increased odds of very long cycle length (OR = 1.21, 95% CI: 0.87-1.68) compared with cycle length of 27-29 days. The inverse association with short cycle length was stronger among 18- to 30-year-old women (OR = 0.68, 95% CI: 0.53-0.87), nulliparous women (OR = 0.66, 95% CI: 0.52-0.84), and women who used both FA and MVs (OR = 0.75, 95% CI: 0.60-0.95). We found no clear association between FA supplementation and cycle regularity and duration and intensity of menstrual bleeding.

Conclusions: FA supplementation was inversely associated with short menstrual cycle length. This association was strongest among women aged 18-30 years, nulliparous women, and women who used both FA and MVs.

Keywords: Folic acid; Menstrual cycle characteristics; Preconceptional supplements; Vitamin supplementation.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adolescent
  • Adult
  • Age Factors
  • Contraception
  • Cross-Sectional Studies
  • Denmark
  • Dietary Supplements*
  • Female
  • Folic Acid / administration & dosage*
  • Folic Acid / pharmacology*
  • Health Behavior
  • Humans
  • Logistic Models
  • Menstrual Cycle / drug effects*
  • Menstruation / drug effects
  • Odds Ratio
  • Parity
  • Time Factors
  • Young Adult


  • Folic Acid