Clinically, there is no such thing as the 3rd day of pregnancy, and if it refers to the 3rd day of intercourse, there are usually no abnormal symptoms. At this point, even if the sperm and egg combine to become a fertilized egg, it will take 6-7 days before it implants in the uterine lining and becomes implanted, and only after implantation will it lead to a change in the levels of various sex hormones, and only then will it appear as an early pregnancy reaction. If you are a woman with regular periods, you can take an early pregnancy test around 15 days after intercourse, and it is usually clear whether you are pregnant or not. If you go to the hospital to draw blood to test HCG, it can be a few days earlier than the urine test. After the initial clarification through blood and urine tests, ultrasound is performed at 6 weeks of pregnancy to clarify whether the pregnancy is intrauterine, and whether the fetal heart and buds are present. Pregnant women usually in about 42 days of pregnancy nausea, vomiting and other early pregnancy reaction, most pregnant women in about 3 months of pregnancy early pregnancy reaction will automatically disappear, during the period to ensure that proper rest and normal diet can be, serious may need to go to the hospital rehydration treatment, do not take drugs.