Closed-mouth pimples (i.e. whiteheads) on the face during pregnancy are a type of acne, and the causes are related to changes in hormone levels, abnormal keratinization of the cells around the hair follicles, and Propionibacterium acnes infections. 1. Hormone level changes: Hormone level changes occur during pregnancy, and if you stay up late for a long time and don’t pay attention to a light diet, sebum secretion will increase, which will lead to whiteheads on the face. 2. Abnormal keratinization of cells around hair follicles: excessive keratinization of cells around the mouth of hair follicles, the formation of keratosis pilaris to block pores, which will affect the discharge of sebum, thus forming acne, resulting in patients with whiteheads on the face of acne. 3. Propionibacterium acnes infection: If Propionibacterium acnes overproliferates, it will stimulate the hair follicles to undergo an inflammatory reaction, causing localized changes such as pimples, which can lead to pregnancy with whiteheads on the face. In addition, heredity, diet, obesity and other factors, can also lead to the onset or aggravation of whiteheads acne, long closed mouth on the face during pregnancy is recommended to seek professional medical practitioners, not unauthorized use of drugs.