Clinically, the vast majority of women do not vomit when they are newly pregnant because the estrogen in the body is relatively low at this time, and the concentration of estrogen has not yet reached a level that can cause vomiting, so vomiting does not occur when they are newly pregnant. As estrogen increases, nausea, vomiting, anorexia, and excessive salivation will gradually occur after about 45 days of pregnancy. If vomiting occurs at the beginning of pregnancy, it is important to pay attention to whether it is caused by hyperemesis gravidarum, as hyperemesis gravidarum causes the body to secrete relatively more estrogen, which will lead to early pregnancy reaction. It is recommended to take blood test for HCG and ultrasound if necessary, mainly to rule out the possibility of hyperemesis gravidarum.