Pregnancy reactions usually appear as early as 4-6 weeks after menopause. Because of the hypercontraction of the stomach and the decrease of gastric acid secretion in early pregnancy, the level of hCG and the increase of free thyroid T4 level in human body are often accompanied by dizziness, weakness, drowsiness, paranoia, anorexia, nausea, vomiting and other symptoms in early pregnancy. Early pregnancy reactions are generally not severe, appearing at 4-6 weeks of menopause, peaking at 8-10 weeks, and mostly disappearing spontaneously after 12 weeks of gestation, occasionally extending to 20-22 weeks of gestation. Current research suggests that the early pregnancy reaction is a protective mechanism for the early embryo. The early pregnancy reaction will lead to a decrease in appetite and reduce the chance of ingesting harmful substances, while it can promote the secretion of insulin and lead to an increase in hCG secretion, which helps the development of the early embryo.