<prompt> Peak HCG levels are by what intrauterine age?7-9 weeks11-13 weeks20 weeks25 weeks  <response>: ANSWTER: A 7-9 weeksREF: Dutta 6th ed p. 58-59HCG is a glycoprotien with two subunitsThe beta subunit is unique to it and is specific.Synth sized by syncytiotrophoblastsHalf life is 24 hoursIn early pregnancy doubling time is 1.4-2 daysCan be detected as early as 8 days following ovulation by immuno assayLevels progressively rise and reach maximum by 8-10 weeks70 dayslst trimesterFalls until 18-20 weeks and remains low until term.Disappears from circulation by 2 weeks 