There are many reasons for pregnant women to feel vertigo suddenly, which should be judged according to the trigger of vertigo and the accompanying symptoms and duration. 1. If the vertigo occurs briefly during the process of getting up suddenly, it is considered to be caused by postural hypotension. 2. If the vertigo occurs suddenly during the process of changing the specific position of the head, presenting a brief rotation of the visual objects, not exceeding one minute, and the symptoms are relieved when the position of the patient’s head is restored, it is considered to be caused by benign paroxysmal positional vertigo. 3. If the vertigo persists and is heavy, and the patient has nausea, vomiting, tinnitus and dullness in the ears, it is considered to be caused by Meniere’s disease.