During pregnancy, the hormone Human Chorionic Gonadotropin (HCG) is released. The hormone is produced by the cells that make up the placenta and aids in the nourishment of the egg after fertilisation. HCG levels can be found using a blood test that must be taken within 11 days of conception, and a urine test that must be done within 12-14 days of conception. The levels usually double every three days or 72 hours. During the first 8-11 weeks of pregnancy, the level will be at its highest. You should keep an eye on your HCG levels.