Human chorionic gonadotropin (hCG) is a hormone produced by the embryo after implantation. The presence of hCG is detected in some pregnancy tests (HCG pregnancy strip tests). HCG is a hormone which maintains the development of a fertilized egg in the woman. It is widely employed in the treatment of infertility. After fusion of sperm and ovum in fallopian tube the fertilized egg attaches to the uterus wall by the placenta. After implantation the cells of placenta start to secret Human Chorionic gonadotropin. Basically, it is a glycoprotein composed of 237 amino acids with a molecular mass of 25.7 kDa.