The absence of coitus does not cause a woman to become pregnant. Delayed menstruation without coitus but a pregnancy test showing pregnancy may be caused by an incorrect pregnancy test, a recent miscarriage or intrauterine residue after a miscarriage, or gestational trophoblastic disease. Using a pregnancy test that has passed its expiration date, or using a pregnancy test in the wrong way may cause the pregnancy test to give the wrong result and show a false positive. If you have just had a miscarriage or if there is residue in the uterus after the miscarriage and the HCG in your body has not dropped completely to normal, you will have delayed menstruation and pregnancy test results even though you have not had intercourse after the miscarriage. Some women with gestational trophoblastic diseases, such as hyperemesis gravidarum and choriocarcinoma, may experience delayed menstruation and pregnancy test results. There are many reasons for delayed menstruation without intercourse but a pregnancy test can show pregnancy, and you should go to the hospital and take a test to determine the specifics.