Vomiting in pregnancy usually lasts for about 6 weeks, but the length and degree of vomiting can vary significantly depending on the individual constitution of the pregnant woman. Vomiting in pregnancy usually occurs around the 6th week of pregnancy and can last until around the 12th week of pregnancy, and is caused by a sharp rise in the level of human chorionic gonadotropin secreted by embryonic trophoblast cells after pregnancy. However, because pregnant women have different levels of tolerance to this rise in hormone levels, there are marked differences in the degree and duration of the vomiting reaction. Some pregnant women experience mild pregnancy vomiting, even just morning sickness, which soon disappears, while others experience severe pregnancy vomiting, which can last until the sixth or seventh month of pregnancy. It is recommended that pregnant women who experience severe vomiting and are unable to eat should go to the hospital in time for treatment.