Having tender breasts, being tired, and not being able to stand foods you used to like may all be early symptoms of pregnancy, but other things can cause these, too. The most reliable early sign that you're pregnant is missing a period, if you're usually regular. Some women don’t notice any early symptoms when they're pregnant.
Before the major indicators of pregnancy kick in, such as a missed period or a positive pregnancy test, there are other tell-tale symptoms that can be triggered 1 week after conception. These early symptoms, which some expectant mothers begin to experience when they are one week pregnant, are a result of the pregnancy hormone hCG (Human Chorionic Gonadotropin).