Pregnancy sickness starts at 4-6 weeks of pregnancy, but it varies from person to person. Early pregnancy reaction usually starts around 4-6 weeks of pregnancy. Due to the different personal constitution of pregnant women, the duration and severity of pregnancy vomiting reaction are different. Pregnancy sickness may be related to factors such as chorionic gonadotropin and mental stress. Pregnant women usually start to experience pregnancy sickness around 4-6 weeks of pregnancy, and the reaction is heavier in the morning. However, the degree and duration of morning sickness varies from pregnancy to pregnancy, and some pregnant women may not experience morning sickness at all. Some pregnant women have a more severe reaction to pregnancy vomiting, which affects their normal life and leads to water and electrolyte balance disorders, requiring medical treatment. When the reaction to pregnancy vomiting is serious, you should go to the hospital in time to see a doctor, under the guidance of the doctor to take the appropriate treatment program.