The menstrual cycle results from a sequence of hormonal activity involving the brain, pituitary gland, ovaries, and uterus. Despite many opportunities for disruption, the cycle is remarkably consistent in most women from month to month.

Emotional and physical stress can affect the menstrual cycle and delay the period. Stress decreases hormone signals originating in the brain. This results in the failure of the ovary to release an egg. This causes an imbalance in the ovarian hormones estrogen and progesterone. The period may be delayed for a few days to a few weeks and may be heavy when it does occur.

Several other conditions, most notably pregnancy, can also delay the period. It should not be assumed that stress is the cause without first checking a pregnancy test and consulting a health professional.