What should hCG level be at 1 week pregnant?

Less than 10 U/L in non-pregnant women. 10 to 25 U/L for a 'borderline' pregnancy result. more than 25 U/L for a postive result.

hCG levels be detected at 1 week

Low levels of hCG may be detected in your blood around 8 to 11 days after conception. hCG levels are highest towards the end of the first trimester, then gradually decline over the rest of your pregnancy.