The duration and severity of early pregnancy reactions vary to a certain extent due to individual differences of pregnant women, but usually, early pregnancy reactions have improved significantly or disappeared at 12 weeks of pregnancy. If the reaction suddenly becomes bigger in the 12th week of pregnancy, factors such as overwork, improper diet, upper respiratory tract infection and thyroid disease should be considered. 1. Overwork: If pregnant women cannot ensure sufficient sleep and rest, often do heavy physical labor, resulting in poor mental state, it can cause the early pregnancy reaction to increase in the 12th week of pregnancy. It is recommended that pregnant women stop heavy physical labor, take proper rest, ensure sleep and relieve physical fatigue, and usually the symptoms can be relieved by themselves after improvement; 2. Improper diet: if eating unclean food leads to the occurrence of gastroenteritis, it will aggravate the reaction of nausea and vomiting, mistaking it for early pregnancy reaction. At this time, it is recommended that pregnant women seek medical advice in a timely manner and follow the doctor’s instructions to determine the treatment plan, and do not use drugs without authorization to avoid the impact on the fetus; 3, upper respiratory tract infection: if pregnant women have rhinitis, laryngitis, tonsillitis and other diseases, it will aggravate the symptoms of weakness and nausea, making the 12-week pregnant women feel that the reaction becomes bigger. If the symptoms are mild, you can not take medicine, proper rest and drink more hot water to relieve the symptoms. If the symptoms are more serious, it is recommended to consult a doctor in time and take antibiotics such as cephalosporin and penicillin that have less impact on pregnant women and fetuses for treatment; 4. thyroid diseases: such as hypothyroidism and hyperthyroidism can lead to big emotional changes, fatigue, drowsiness, loss of appetite, bloating, constipation and other manifestations, making pregnant women think that the early pregnancy reaction is aggravated. It is recommended to have a blood test for thyroid function and follow medical advice for treatment. Since thyroid disorders during pregnancy may lead to hypertension in pregnancy, it is recommended that pregnant women should have regular maternity checkups and perform self-testing of blood pressure on a daily basis so that any abnormalities can be detected and treated early. In summary, if a pregnant woman has a large reaction at 12 weeks, she can go to the hospital to improve the relevant examination to clarify whether there is an organic lesion. If there is no organic pathology, you can reduce the discomfort by eating a light diet, eating less and more often, keeping warm and avoiding strain.