It takes at least about 7 days after intercourse before it is clear whether you are pregnant or not. This is because after intercourse the sperm and egg combine to form a fertilized egg, and it takes about 7 days for fertilization to occur. The synthesis of trophoblast cells and the secretion of human chorionic gonadotropin begins on the 6th day of fertilization, and the pregnancy can then be confirmed by checking the hormone level in the blood and subsequently in the urine. An ultrasound can be performed at 40 days of pregnancy or more to find out if the pregnancy is in the uterus and to see if the embryo is developing normally. The hormone levels in a woman’s body change dramatically once she becomes pregnant, which leads to the cessation of menstruation and then early pregnancy reactions such as nausea, vomiting, weakness and dizziness. Pay attention to the reasonable arrangement of work and rest during pregnancy and avoid overexertion to prevent the development of the fetus from being affected.