4D baby left kidney severe hydrocele need to do further examination of chromosomes, if chromosomal abnormalities, need to terminate the pregnancy; if not, then the pregnant woman to do a good job of pregnancy health care at the same time observation can be. 4D baby with severe left hydronephrosis needs further examination, such as non-invasive DNA, amniocentesis, etc., to check the chromosomes, if the result is chromosomal abnormality, then the severe hydronephrosis of the left kidney is judged to be a congenital anomaly, and the pregnancy needs to be terminated. If not, the development of the left kidney may be relatively delayed, and may return to normal after the pregnant woman replenishes sufficient nutrition, ensures sleep, and continues to observe for a period of time. It is recommended that once a pregnant woman discovers that her baby’s left kidney is severely hydronephrosis, she should not be overly anxious, and should seek timely and complete the relevant examinations and treatments.