Bad breath in pregnant women needs to be controlled by oral hygiene, which can be removed by rinsing or dental medication. The common cause of bad breath in pregnant women is gingivitis caused by poor oral hygiene, or tooth decay, or gastrointestinal tract digestive function is not perfect, need to find out the cause of symptomatic treatment. If a pregnant woman does not brush and rinse her teeth in time after eating, food residue or plaque will accumulate around her teeth, stimulating the gum tissue to bleed and forming gingivitis. Changes in hormone levels in the body during pregnancy can also aggravate gingivitis and cause bad breath. This condition can be controlled by rinsing the mouth with mouthwash, or by effective brushing of the teeth for oral hygiene. If plaque or soft tartar calcifies under the action of saliva and forms tartar that is difficult to remove, it can be removed by ultrasound, followed by rinsing around the gums with hydrogen peroxide and local application of iodine glycerin to relieve the symptoms of gingivitis and improve bad breath. Bad breath of pregnant women may also be caused by eating indigestible food, such as beans or milk, and protein, meat, etc. The digestive function of the gastrointestinal tract is disturbed, and food is not completely decomposed in the gastrointestinal tract, which can also lead to putrefactive bad breath. This situation requires a light diet to reduce the burden on the gastrointestinal tract. Therefore, bad breath of pregnant women can be removed by brushing or gargling with mouthwash, or by scaling the teeth with medicine and eating a light diet.