I tested negative for a pregnancy test but my menstrual period lasted for two days?

Tests are accurate: Home pregnancy tests are very accurate and not affected by foods, herbs, common illnesses, STD's, vaginal spotting, or medications. A test gives a reliable result by 3 weeks after sex (3 weeks after when conception might have happened). If done sooner, a negative result may be due to testing too early such as less than 2 weeks after conception. If still worried, one can retest after 1 more week.