Low urea in pregnant women may be caused by increased renal filtration rate, increased blood volume, and low protein intake. 1. Increased renal filtration rate. After pregnancy, due to the increase in renal filtration rate, urea nitrogen will be eliminated into the blood, which will cause a decrease in blood urea nitrogen. 2. Blood volume increases. During pregnancy, blood volume increases by 30% compared to the normal state, and the blood of pregnant women is diluted, which leads to the dilution of substances in the blood, and the concentration of urea nitrogen is diluted and will be low. 3. Low protein intake. Nausea, vomiting, loss of appetite and other symptoms during pregnancy, resulting in lower than normal nutrition and protein, can also cause low urea nitrogen in the body. Low urea during pregnancy generally has little effect, and it is recommended that pregnant women reasonably increase nutrition and eat more high-protein lean meat, fish, eggs, milk, soy products and other foods. If you experience any discomfort, it is recommended that you seek medical attention in a timely manner.