Nausea and tiredness are among the first typical pregnancy symptoms, though for most women, missing a menstrual period is usually the very first sign that they are pregnant. Typical pregnancy symptoms are related to the pregnancy hormone hCG. They usually do not appear until later on in pregnancy, often weeks after implantation, when hCG is high enough to induce these symptoms. The best way to know for sure that you're pregnant is with a pregnancy test. But there are early symptoms of pregnancy that can alert you to the fact that you may be pregnant and should have a test.