your fetus most likely has what is called pylectasis (fluid noted in the renal pelvis of the kidney). if this is what it is most likely it is not all that significant. however your physician is correct that it should be followed throughout pregnancy because if it increases in size (more then 10 mm) it changes from most likely being normal to half the time being normal and half needing further workup. we see this frequently in different fetuses. most times it is normal. did you have any testing such as nuchal translucency or quad screen? this also helps in figuring out if there are any risks. .
i am pregnant and found out that there is extra fluid on one of my baby's kidneys. what does this mean?