Diarrhea occurs in women after fertilization of the egg, mainly due to hormonal changes in the body. After fertilization, the level of human chorionic gonadotropin and progesterone in the body will increase significantly, which will lead to changes in the plant nervous function and subsequently affect the gastrointestinal function, resulting in diarrhea. The degree of diarrhea will be mild and is a normal physiological phenomenon that will not affect the body of the pregnant woman and the development of the fetus, and does not require special treatment. If violent diarrhea occurs after the fertilized egg is laid, or even dehydration or electrolyte disturbance, it may be related to unclean diet, food poisoning or pre-eclampsia, so it is important to pay attention to it and seek timely specialist treatment to avoid adverse effects on the fetus.