The so-called symptoms of the second day of pregnancy are actually what is usually referred to as the feelings of the pregnant woman herself in early pregnancy. As a result of pregnancy, her hormone levels change drastically, and her chorionic gonadotropin, or HCG, and progesterone levels increase significantly, leading to abnormalities in various organs of the body. For example, there may be bilateral breast enlargement and consequently bilateral breast swelling and pain. In addition, it can lead to a decrease in the secretion of stomach acid, which in turn can cause a decrease in appetite. Some pregnant women have vomiting in the morning, which is also caused by the decrease of stomach acid. Therefore, if you experience vomiting in the morning, reduced appetite, intercourse during ovulation, and breast pain, you should first consider the possibility of pregnancy.