There is no reaction to pregnancy, it may be a normal phenomenon, or it may be the embryo is arrested. 1. Normal phenomenon: early pregnancy will generally appear early pregnancy reaction, in pregnancy about 40 days will appear nausea, vomiting and other symptoms, pregnancy about 3 months will disappear. But not all pregnant women will have early pregnancy reaction, some pregnant women do not have any reaction, early pregnancy reaction is also different from person to person. 2. Embryonic arrest: If the embryo stops developing, the level of human chorionic gonadotropin in the body will decrease, resulting in early pregnancy reaction will be reduced or disappeared, if there is any abnormality, it is recommended to go to the hospital in a timely manner, and it can be determined by ultrasound examination. During pregnancy, women should regularly go to the hospital for obstetric examination, so as to determine the development of the fetus, do not rely solely on the early pregnancy reaction to determine the development of the embryo.