The air circulation in haze days is not smooth and contains a variety of harmful substances, such as sulfide, nitrogen compounds, etc., which can easily cause cough, nasal congestion, epistaxis, chronic pharyngitis, etc. Some pregnant women will have elevated blood pressure and become upset, especially pregnant women who already had high blood pressure before pregnancy. In this kind of weather, they are more likely to develop gestational hypertension or preeclampsia. Haze weather can also easily cause intrauterine hypoxia, leading to increased fetal movement.