My girfrend and i had unprotected sex and 19 of feb her period came normal at 24 of feb she is now late this mouth cuple of days pragnacy test negative ?

Tests are accurate: Home pregnancy tests are very accurate and not affected by foods, herbs, common illnesses, sexually transmitted diseases, or medications. A correctly done urine test gives a reliable result 3 weeks after sex (3 weeks after when conception might have happened) or 1 week after missing a period. If done sooner, a positive result is likely real, but a negative result may be due to testing too soon.

Also...: If the pregnancy test is negative and you still do not have your period, I suggest you repeat the test about a week later. There are other causes of not having a normal period but it’s important to make sure that pregnancy is or is not the cause.