How does a folic acid deficiency affect the menstrual cycle?

FA & menstrual cycle: Folic acid is used prior to & during pregnancy to prevent development of neural tube defects. Some studies have shown minor trend towards decreased short cycles & ^ in very long cycles or irregularity. Women with heavy or long periods with iron deficiency anemia, may take Folic Acids/ multiple vitamins to build up red blood cells. see: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4567938/