Fetal left kidney cyst 6*6mm is generally not considered serious, continuous observation is recommended, and active treatment is needed when necessary. 6*6mm renal cyst, if it belongs to simple renal cyst, the clinical symptoms are usually mild, this kind of cyst tends to grow slowly, generally can be diagnosed as a benign disease, do not need special treatment, but need to receive regular review. If the cyst is found to be increasing in size, leading to compression of the surrounding renal parenchyma, active treatment is required. In addition, during pregnancy, pregnant women need to undergo regular obstetrical examinations, and any problems found need to be dealt with in a timely manner, so as to avoid affecting their own health and the growth and development of the fetus. At the same time, during pregnancy, pregnant women need to actively do a good job in all periods of care under the guidance of obstetricians.