Normally, the successful implantation of a fertilized egg should take about four to five days before the fertilized egg can make its home in the uterus. After sex, hundreds of millions of sperm will travel towards the woman’s vagina, from which they will enter the uterine cavity and then move to the inside of the fallopian tubes. The fastest swimming sperm inside the fallopian tube will unite with the egg cell. The head and part of the body of the sperm enters the secondary oocyte to form a fertilized egg, a process also known as the zona pellucida reaction. After the sperm and egg have successfully united to form a fertilized egg, the fertilized egg gradually travels to the uterine cavity until it enters the endometrium and then implants, which takes about seven days from the time the sperm enters to the time of successful implantation. Normally, the blood chorionic gonadotropin rises gradually after implantation. Therefore, a blood HCG test can be done about seven to ten days after sexual intercourse to confirm whether you are pregnant.