With the popularity of prenatal 4D ultrasound, some fetuses are also detected with hydronephrosis. What causes hydrocele in the fetus and whether the baby with hydrocele should be born or not? These questions make mothers-to-be very anxious, so I’ll give you a general introduction below. About fetal hydronephrosis, generally can be divided into the following two cases: 1, self-recoverable: this part of the fetus in the development process of the temporary emergence of the urinary tract (renal pelvis, ureter, etc.) malfunction or structural abnormalities, but with the development of the fetus, this malfunction and abnormalities will gradually improve, especially after birth, with the development of the urinary tract, especially the ureter perfect, hydronephrosis will gradually reduce or even disappear. 2.Non-self-recoverable: This kind is common in congenital ureteral stenosis, and is mostly accompanied by renal function damage. After the birth of such fetuses, if the hydrocele becomes increasingly serious after regular review of ultrasound, the necessary detailed evaluation and treatment should be carried out in a timely manner. In conclusion, if fetal hydrocele is found, do not rush to terminate the pregnancy, mothers-to-be should relax, and at the same time regularly review the ultrasound to observe the changes of hydrocele, and promptly consult the relevant clinicians in obstetrics and pediatric urology to get timely treatment.