What is the longest implantaion bleeding last for?

Implantation: Implantation bleeding is not really as common as the internet would have you believe. When it does happen it's usually 6-12 days after ovulation. A pregnancy test 7-10 days after unprotected intercourse is much more helpful. If you are trying to avoid pregnancy considering your age please see your doctor to discuss birth control options. If you are trying to get pregnant take a prenatal vitamin