It takes about 10 days after the fertilized egg has been laid before it can be measured in the urine, and usually self-testing for pregnancy involves testing for HCG values, a hormone produced by the placenta. In most cases, HCG can appear in the urine of a pregnant woman a few days after she becomes pregnant with a child, but because the amount of HCG is not very large, it is difficult to detect it at the beginning, and it takes about 12 days for the amount of HCG to be noticeably larger, that is, it can be detected when the menstrual period has been delayed for more than a week or 18 days after coitus. Since it takes about a week to reach the uterine lining after the egg and sperm combine and complete implantation at this time, it takes about 8 days for HCG to enter the human urine, i.e., it takes about 10 days after the fertilized egg is implanted before it can be detected in the urine.