What causes a prolonged menstrual cycle?
A late or missed period could be caused by any of the following:
Pregnancy, Stress, Physical stress like a severe illness, STD's,
rapid weight loss or gain, strenuous exercise, dieting, or binging
and purging, changes in your usual routine like going on vacation
can cause this also. Hormone imbalance is one cause, polycistic
ovary syndrom can also be a cause. Problems of the thyroid gland,
pituitary gland, adrenal glands, or ovaries can be rare causes of
irregular periods.