You can test for pregnancy during your period, but you may not be able to detect it. If your period is light, you can go to the hospital to have a blood test for HCG to confirm whether you are pregnant. If you have your period, but it is light, you can use a pregnancy test, if it is two bars or a weak positive, you need to go to the hospital to take a blood test for HCG to confirm whether you are pregnant or not. If your period comes at a normal time, you can use a pregnancy test, if it is one bar usually not pregnant, if necessary, you can go to the hospital to check the blood HCG for a clear diagnosis, to confirm whether you are pregnant or not. You can test for pregnancy during menstruation, and it is recommended that your doctor directs you to do so according to your specific situation.