Human chorionic gonadotropin (hCG) is a glycoprotein hormone produced and developed by the placenta shortly after fertilization. In a normal pregnancy, hCG can be detected in both urine and serum or plasma as early as 7 to 10 days after conception. The level of hCG continues to rise very rapidly, often exceeding 100mIU/ml by the first missed menstrual period and peaking in the range of 100,000-200,000mIU/ml at approximately 10-12 weeks of pregnancy. The occurrence of hCG in both urine and serum or plasma soon after conception and its subsequent rapid increase in concentration during early gestational growth makes it an excellent marker for early detection of pregnancy.