Under normal circumstances, the vast majority of pregnant women in 12 weeks of pregnancy early pregnancy reaction has significantly improved or even disappeared. If the early pregnancy reaction suddenly becomes more obvious around 12 weeks, it is necessary to consider whether there are thyroid problems, such as hypothyroidism, hyperthyroidism, which will lead to a series of uncomfortable situations, also lead to early pregnancy reaction, it is recommended to take blood to check the thyroid function. If the pregnant woman does not rest well, poor mental state, can also lead to early pregnancy reaction occurs. If a pregnant woman has a cold, upper respiratory tract infection, pneumonia, etc., it can also lead to nausea and discomfort. If eating something unclean leads to gastroenteritis, it can also lead to a greater reaction.