Some pregnant women will be told that urine ketone bodies are weakly positive when they undergo routine urine examination during pregnancy. Urine ketone body weak positive is what causes, first of all, to clarify the ketone body is the body fat metabolism abnormalities in the formation of a product, a variety of reasons that may affect the normal metabolism of fat, may lead to the body ketone body produces too much, the urine ketone body appeared positive or weak positive reaction. Common causes include: 1, gestational diabetes in pregnant women, in the case of prolonged poor glycemic control may lead to abnormal fat metabolism, ketone body elevation. 2, the reaction of pregnancy vomiting is too heavy women, due to insufficient carbohydrate intake, will lead to accelerated fat decomposition and metabolism and ketone body increase. 3, fever, prolonged starvation, over-dieting and other situations, may lead to abnormal fat metabolism and ketone bodies.