The process of fertilization is when the sperm and the egg join together. The fertilization process takes about 24 hours. Fertilization begins when an energized sperm enters the zona pellucida of the egg cell. The completion of the fertilization process is marked when the chromosomes of the sperm and egg fuse together. How long does it take for the sperm and egg to unite before pregnancy occurs? This is a concern for many women who want to have a baby, so let’s find out. 1. The fertilization process takes about 24 hours. The fertilization process begins when an energized sperm enters the zona pellucida of a secondary oocyte. The process of fertilization is completed when the chromosomes of the egg nucleus and sperm nucleus fuse together. 2. During oogenesis and follicle formation, the cells of the fertilized egg undergo metabolic changes and the trophectoderm cells adhere to the inner surface of the zygote by protrusions overlying neighboring cells. Because the cell surface can transmit environmental influences to the embryo, changes in the cell surface can be explained by nutrient uptake, differentiation, preparation for implantation, or mitosis. 3, The fertilized egg divides into 2 cells after 36 hours in the oviduct and into 16 cells after 72 hours and is called a mulberry embryo. 4. On the 4th day after fertilization, the cell mass enters the uterine cavity and continues to develop in the uterine cavity, by which time the cells have split into 48 cells and become the blastocyst ready for implantation. The blastocyst can secrete a hormone that helps the blastocyst to bury itself into the endometrium. 5. On the 6th-7th day after fertilization, the blastocyst begins to implant. The location of implantation is mostly in the upper third of the uterus. Completion of implantation means that the embryo has been placed and the placenta has started to form to conceive a fetus. So, 6-7 days after the union of sperm and egg, the fertilized egg will complete the process of implantation. The answer to how long after the union of sperm and egg to get pregnant is 6-7 days.