If the fetus has hydronephrosis observed through ultrasound during pregnancy, it should be judged according to the hydronephrosis. If the fetus has mild hydronephrosis, it does not need treatment and there is basically no harm to the fetus; if it is severe hydronephrosis, it is considered to be due to ureteral stenosis and other reasons, which can cause pelvic separation, and regular ultrasound is needed to observe the changes of the fetus’ hydronephrosis. If the fetal hydronephrosis exceeds 7mm in late pregnancy, fetal abnormalities should be considered and the baby should be followed up until after birth. Usually, we should pay attention to avoid spicy, greasy, fried and puffed foods, and not to consume too much salt, have enough rest time, and must keep a relaxed mood, as the mental state can affect the fetal development.