No ejaculation will not cause pregnancy. Conception must occur when a normal sperm combines with an egg to form a fertilized egg that implants in the uterine cavity to produce pregnancy. During sexual intercourse, if semen is not ejaculated into the vagina, the egg loses the opportunity to combine with the sperm and cannot form a fertilized egg, and conception cannot occur. The unfertilized egg forms a corpus luteum, atrophy occurs, the endometrium is shed, and bleeding occurs in the vagina, which is expelled from the body along with menstrual blood. Pregnancy can be ruled out by having normal menstruation every month after intercourse. During sexual relations, those who are afraid of unwanted pregnancy should always wear condoms to prevent sperm from entering the vagina and achieve the effect of contraception.