renal pelvic dilation?

had my 20 week scan last week was told that there was a slight swelling to the renal pelves they measured 5.2 and 5.6. consultant has explained what could cause it, we are having another scan at 27 weeks to see if the swelling has gone down, did anyone have this turn up on their anomaly scan? what happened, did it go down before the birth or not? if it didnt did it cause any problems for baby after the birth?

i'm not really worried it seems to be quite common, especially among boys which is what we are having. i just wanted to know about other peoples experiences of it.