Why Is My Period Late?

When your period arrives later than expected, it is usually because ovulation was delayed during the follicular phase. The luteal phase (the time from ovulation to bleeding) stays fixed at roughly 12 to 14 days, but the pre-ovulation phase is sensitive to external factors.

8 Common Causes for Period Date Shifts

  1. Acute & Chronic Stress: High cortisol suppresses GnRH hormone secretion.
  2. Travel & Circadian Disruption: Time zone shifts alter melatonin and reproductive rhythms.
  3. Recent Viral Illness: Fevers and immune stress can postpone follicle maturation.
  4. Significant Weight Changes: Caloric deficits or rapid gains alter estrogen levels.
  5. Intense Exercise Surges: Over-training can cause hypothalamic amenorrhea.
  6. Thyroid Hormone Fluctuations: Hypothyroidism or hyperthyroidism alters menstrual frequency.
  7. Polycystic Ovary Syndrome (PCOS): Elevated androgens prevent regular ovulation.
  8. Perimenopause: Natural ovarian follicle decline in women in their 40s.