Always want to drink water at night in late pregnancy may be normal, such as dietary factors, frequent urination and other causes, or it may be an abnormal performance, such as gestational diabetes, vitamin B2 deficiency caused. 1. Dietary factors: late pregnancy is more like to eat heavy salt, heavy oil, heavy sugar foods, more easily thirsty, will always want to drink water at night, this situation is normal. 2. Frequent urination: late pregnancy fetal growth and development is relatively fast, the uterus will also increase in size more obvious, increased uterine compression of the bladder will appear frequent urination performance, urination more often will cause thirst, the night will always want to drink water, this situation is also normal. 3. Gestational diabetes: patients with gestational diabetes, due to elevated blood glucose and polyuria, resulting in increased plasma osmolality, the patient will always feel thirsty, and always want to drink water at night, this is the state of the disease, is not normal performance. 4. Vitamin B2 deficiency: the body needs more nutrients after pregnancy, the body lacks vitamin B2 will appear dry mouth symptoms, to the evening will always want to drink water, this situation is also abnormal. There are more reasons why you always want to drink water at night in late pregnancy, and it is seriously recommended to go to the hospital for examination and judgment.