I took a home pregnancy test, which was negative. If you have been sexually active, there is always the possibility of pregnancy. Another reason for a delay of menses is an irregular cycle, which is not uncommon. A number of physical and psychological factors can upset a woman's life temporarily and cause her period to be late. High or low levels of thyroid hormones may cause periods to stop, occur infrequently, or not to start at all.
Strenuous exercise can cause periods to stop.
Apparently, exercise causes the pituitary to secrete less of the hormones that stimulate the ovaries, so the ovaries produce less estrogen. If your period does not start, try another pregnancy test or see your physician. 882-7000 to make an appointment with a University of Missouri Health Sciences Center physician. Earlier this month I went to the clinic for a pregnancy test because I was having very light periods and showing other signs of being pregnant. They gave me three different kinds of blood tests and all were negative.