Can you have nausea after only a week or two of conception?

Unlikely. The cause of nausea and vomiting in pregnancy is multifactoral, one factor being the rapidly rising levels of HCG in early pregnancy. However, HCG is undetectable until about day 7 after fertilization. The levels peak between 8 and 11 weeks of pregnancy; which is typically when the symptoms are the worst.
Unlikely. The cause of nausea and vomiting in pregnancy is multifactoral, one factor being the rapidly rising levels of HCG in early pregnancy. However, HCG is undetectable until about day 7 after fertilization. The levels peak between 8 and 11 weeks of pregnancy; which is typically when the symptoms are the worst.