This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Endocrinology in Relation to Reproduction, Subject name: Gynaecology & Obstetrics
Peak HCG levels are by what intrauterine age? 
Select and explain. 
A. 7-9 weeks, B. 11-13 weeks, C. 20 weeks, D. 25 weeks
A: 7-9 weeks
Answer: A: 7-9 weeks 
Explanation: 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 weeks/70 days/lst trimesterFalls until 18-20 weeks and remains low until term.Disappears from circulation by 2 weeks