Implantation bleeding usually happens about 6–12 days after conception, with most sources grouping it around 7–14 days after the egg is fertilized. In many people this ends up being roughly a few days to a week before the expected period, which is why it is often mistaken for a light or early period.

Typical timing window

• Many medical and pregnancy resources describe implantation (and any associated bleeding) as occurring roughly 6–10 days after conception.

• Other reputable sources broaden this to about 10–14 days after conception, still within the two weeks after fertilization.

What this means in practice

• If unprotected sex led to conception around ovulation, light spotting that appears about one to two weeks later could be implantation bleeding, especially if it is lighter and shorter than a normal period.

• Not everyone has implantation bleeding, and spotting can also be caused by other things, so a home pregnancy test after a missed period or about 14 days after possible conception is usually recommended to clarify.