Identified in the early 20th century, human chorionic gonadotropin (hCG) is a glycoprotein hormone that rises quickly in the first few weeks of pregnancy, typically reaching a peak at 8- to 10-weeks gestational age.hCG is produced by what will become the placenta.[6 hCG testing can be performed with a blood (serum) sample (typically done in a medical facility) or with urine (which can be performed in a medical facility or at home). The assays used to detect the presence of hCG in blood or urine are generally reliable and inexpensive. Secretion of hCG can occur as soon as 6 days following ovulation and on average 8-10 days following ovulation; this is the earliest hCG can be detected in a blood sample.The hCG concentration in blood is higher than in urine. Therefore, a blood test can be positive while the urine test is still negative.[10