The sperm and egg unite to form a fertilized egg which usually lays 6-7 days after fertilization. The fertilized egg moves to the uterine cavity 3 days after fertilization and begins to implant 6-7 days later. The implantation site is mostly in the anterior or posterior wall of the upper uterine body and the gap is mostly repaired on the 11th-12th day of fertilization. The fertilized egg grows and develops on the endometrium and gradually forms an embryo. A weak positive test can be detected by early pregnancy test paper 3-4 days after fertilization, and a woman can see a small pregnancy sac by ultrasound about 20-30 days after fertilization. Some women are prone to early pregnancy reactions such as nausea, vomiting, weakness, drowsiness, etc., while some may also experience bleeding from implantation, and those who are sensitive may have symptoms such as soreness or cold. In addition, because the fetus is fragile in early pregnancy, it is easy to induce miscarriage, so we need to pay attention to protect the fetus, pregnant women need to avoid contact with toxic and harmful substances, avoid collision with the abdomen or fall, and timely supplementation of folic acid to prevent fetal neural tube malformation.