The reaction usually starts on the 40th day of pregnancy, i.e. around 6 weeks of pregnancy, and some patients will experience early pregnancy reaction around 1 week of pregnancy. At 6 weeks of pregnancy, the serum level of chorionic gonadotropin increases significantly, the estrogen and progesterone in the body rise, and hormone fluctuations are large, so most pregnant women will have early pregnancy reactions such as nausea, vomiting and loss of appetite during that period. Due to the inconsistent physical condition of pregnant women and their sensitivity to hormone increase, some pregnant women are more sensitive to hormone fluctuation, and early pregnancy reaction can appear when their serum chorionic gonadotropin starts to rise around one week of pregnancy. Don’t worry too much about the early pregnancy reaction, it is a normal pregnancy phenomenon. If you have a mild early pregnancy reaction, you can eat less and more meals and avoid stimulating food to reduce the early pregnancy reaction. If you have a severe early pregnancy reaction, you should pay attention to replenish fluids in time and keep your mood relaxed.