The formation of a new life is an amazing process: starting with the union of a tiny sperm from the father and an egg from the mother, this little life spans about 280 days in the mother’s womb, grows into a croaking baby, and then begins a whole other journey. The process of life occurrence is very sophisticated and complex, but we have been able to understand the formation of the early embryo relatively well. The ability of a couple to form an embryo after sex and implant it in the uterus to achieve a successful pregnancy is influenced by many factors. Let’s learn more about them. The most important thing for a successful pregnancy is to have a mature, healthy egg. Not only because half of the genetic material in an embryo comes from the egg, but also because the egg provides the material conditions for early embryonic development. Therefore, the quality of the egg is very critical. Generally speaking, the quality of eggs decreases with age. Some studies have shown that the quality of eggs begins to decline significantly in women over the age of 35, so it is best for women to have children before the age of 35. As women age, the number of eggs becomes less and less, and at the same time, the quality declines rapidly, so fertility declines, a trend that cannot be reversed by current medical science. Therefore, it is important for women to plan their family and have a baby at the right time. If you have been planning to have a baby for a year and still do not see success, you need to seek medical attention as soon as possible. In addition to age, the quality of eggs is also related to genetics and environment. Genetic influences are rare and difficult to detect and can only be detected during IVF in vitro fertilization and culture, and there is no effective way to improve this aspect once it occurs. In addition to rare genetic influences, most women’s egg quality is also influenced by the environment. We can try to improve egg quality by avoiding adverse environmental influences, such as avoiding exposure to reproductive toxic chemical products such as pesticides, paints, heavy metals, etc. A good lifestyle and diet is also beneficial for producing healthy eggs. The birth of a new life must also be accompanied by a sufficient number of motile sperm. Studies have shown that up to 100,000 sperm need to be around the egg to ensure good fertilization rates. If the sperm count is not high enough or if the number of motile sperm is slightly lower, we can improve the chances of conception by using intrauterine insemination, where the semen is specially processed and enriched with a sufficient concentration of motile sperm to be injected into the uterine cavity. If the number of sperm is even lower, or if no sperm can be found in the semen and only sperm are surgically recovered from the epididymis or testicular tissue, the only way to achieve fertilization is through the “second generation IVF” technique, medically known as intracytoplasmic single sperm injection (ICSI). In the natural state, one sperm is the first to penetrate the zona pellucida outside the egg, causing a series of changes that prevent other sperm from continuing to enter the egg, ensuring the union of one egg and one sperm to form a diploid fertilized egg. During in vitro fertilization, normal fertilization cannot be achieved if the egg is immature or overly mature, or if there are abnormalities. On the other hand, if the sperm undergoing ICSI fertilization has a functional abnormality, although we artificially help the sperm to drill into the egg, the abnormal sperm will not be able to cause the series of reactions necessary to undergo fertilization and will not be able to fertilize properly. Therefore, when IVF is performed, the number of embryos normally fertilized is generally less than the number of eggs obtained, and the exact ratio varies depending on the quality of the eggs and sperm. In a natural pregnancy, a clear and functioning fallopian tube is also needed for the sperm and egg to meet and complete fertilization. The sperm has a tail and can swim, but the egg is round and has no tail or legs. The egg matures and is discharged from the surface of the ovary located in the abdominal cavity, so how do the egg and sperm meet? It turns out that although the egg does not swim, the fallopian tube can peristaltically move and the cilia inside the tube can push it. The egg is picked up by an umbrella-like structure at the end of the fallopian tube and pushed towards the uterine cavity by peristalsis. The fertilized egg continues to slowly advance towards the uterine cavity with the peristaltic movement of the fallopian tubes and enters the uterine cavity on the fifth day of fertilization. If the fallopian tubes are blocked, then the sperm and egg cannot meet and complete the fertilization process; when there is inflammation in the fallopian tubes, it also affects the function of the tubes and also cannot complete its mission; if the inflammation acts for a longer period of time, the fallopian tubes may become watery and the tubes not only lose their function, but the inflammatory factors can also have toxic effects on the embryo. When the fallopian tubes lose their function, for example, when a couple with normal ovulation and normal semen quality cannot get pregnant after more than 1 year of regular sex, it is very likely that the fallopian tubes cannot play their role as a “magpie bridge” and we need to use “IVF” to remove the eggs through surgery. The eggs are surgically removed, fertilized with sperm in a Petri dish, and the embryo is sent through the uterine cavity. Normally, the fertilization process is completed within 12 hours of ovulation, and with IVF we usually add the right concentration of processed sperm to the eggs in a Petri dish within 4 hours of egg retrieval to allow them to complete the fertilization process. The sperm enters the egg and awakens the sleeping egg to form a diploid fertilized egg, marking the birth of a new life. We observe fertilization on the first day after egg retrieval by looking at the number of male and female protoplasts under a microscope to select normally fertilized fertilized eggs. The fertilized egg begins to divide 24-30 hours after fertilization, with each division being one cell in two and the two newly formed daughter cells being essentially equal in genetic material and cytoplasm. The rate of division in a normal embryo is 4 oocytes observed on the second day after egg retrieval, 8 oocytes on the third day, a mulberry embryo of about 100 cells on the fourth day, and a blastocyst with an inner cell mass and an outer trophoblast layer on the fifth day. Recent studies have shown that the developmental potential of embryos decreases if their early division rate is slower than normal. Therefore, a 4-cell embryo with uniform cell size on day 2 is a good quality embryo; an 8-cell embryo with uniform cell size and little debris on day 3 is a good quality embryo; a good quality embryo on day 4 is a mulberry embryo; an embryo on day 5 should develop into a blastocyst; and a blastocyst hatches from the zona pellucida on day 6. Too fast or too slow early embryo division suggests some abnormality in the embryo. On the other hand, the timing of embryo division is not entirely consistent, but the observations are evaluated only at very brief times, so the obtained embryo scores are not fully representative of the embryo development. In the natural state, the ectoderm interacts with the endometrium after the embryo enters the uterus, and if the embryo has developmental potential, the ectoderm continues to develop, and 11-12 days after fertilization trophoblast cells implant in the endometrium and secrete human chorionic gonadotropin HCG. HCG secretion increases over time, and at about 14 days after transfer there can be a high enough concentration of HCG in the blood to be known by testing. As the embryo develops, the placenta gradually forms and the embryo gradually differentiates into organs such as the brain, spinal cord and heart. the umbilical cord can be seen after 7 weeks and the embryo grows into a fetus from the 8th week onwards. The baby then continues to grow in the mother’s womb until full term, when it comes to earth from the heavenly womb to begin another part of the saga of his/her life.