Late periods and 3 Negative Tests

Dear Ask The Doctor: I am late on my period by 11 days, I had some spotting after sex but 3 negative pregnancy tests. Could I still be pregnant?

Dear EMily: A pregnancy test aims to detect the presence of the beta subunit of human chorionic gonadotropin (hCG) found in urine and blood. Home pregnancy tests have a sensitivity of close to 97% when used correctly. This means that 97% of people that are pregnant will have a positive test. User error accounts for most of the tests that turn out to be wrong. You could see your doctor for a confirmatory blood HCG test which is the most sensitive for pregnancy.