8 months old baby suddenly less urine should be considered from the following aspects: 1, less intake, poor diet, eating less or drinking less water, resulting in a small metabolism and reduced urine volume, most of which is a problem in this area. This situation should pay attention to careful feeding, diet diversification, balanced nutrition. 2, more excretion, baby sweating through the skin evaporation to discharge part of the water, which pay attention to not let the baby too hot, appropriate increase or decrease clothing. If there is vomiting, diarrhea, body fluids and various ions discharged more, body dehydration can also lead to less urine, need to drink more water or oral rehydration salt to supplement the amount of liquid. 3, pathological aspects, observe whether the eyelids are swollen and both lower limbs are swollen, pay attention to acute nephritis and urinary tract infections, and also to observe whether the bladder is full, whether there is urinary retention.