The process of sperm and egg union is called fertilization or conception, and conception is the beginning of pregnancy. About two weeks before each menstrual period, a mature egg is discharged from the ovary and gradually moves to the uterus with the peristaltic movement of the fallopian tubes. And while the egg is maturing and expelling the follicle, the inside of the uterus is ready to receive the egg. If sexual activity occurs during ovulation, the male ejaculate passes through the woman’s vagina and uterus to the fallopian tube where it meets the egg and unites to form a fertilized egg, completing the fertilization process. After fertilization, the fertilized egg soon begins to divide, increase geometrically and move towards the uterus, where it reaches the uterine wall and implants in the fully prepared endometrium, where it will settle and develop in the uterine cavity, completing the process of conception. Conception is a complex physiological process and the presence of a sufficient number of normal sperm with considerable motility and a mature and healthy egg are the basic conditions that both men and women must have in order to conceive. If there is no normal sperm or if the sperm count is too low and the motility is low, or if the woman does not ovulate or cannot catch an ovulation, conception is not possible. In addition, if the fallopian tubes are inoperative or the environment for fertilized eggs to implant is poor, the normal process of conception is usually not completed and infertility is formed. Therefore, if fertility is desired, it is recommended that both men and women undergo a series of tests to ensure a normal pregnancy and a healthy baby.