You may take a pregnancy test while bleeding or appearing to be on your period, because any blood that mixes with your urine has no effect on the test's results. (However, bear in mind that a period is usually a good indicator that you are not pregnant.) If you are taking the test at home, it should say so on the packaging. If you are seeing a doctor, they will let you know when it is acceptable to take the test. A negative test does not guarantee that you are not pregnant. Many women have false negatives, meaning that the test detects pregnancy hormones even when there are no fetal cells present in the uterus. Other factors such as age, weight, previous pregnancies, and menstrual cycle phase can also affect test results. A positive test does not guarantee that you are pregnant either. Some women have false positives, meaning that the test detects pregnancy hormones when there are no embryos present in the uterus. In conclusion, yes, a negative pregnancy test while spotting does not rule out pregnancy. It may be best to wait until you stop bleeding before taking another test.