Placenta is weird.

Found out It sits low and I have something called left rental pyelectasis. I guess it's more common with male pregnancies and can cause issues on his kidneys and Urinary tract. I'm not worried about it because most cases it fixes itself. also his kidneys looked good on the anatomy scan. but I'm afraid to tell my mom because she suffered kidney failure and almost died now only has one kind of functioning kidney and would feel terrible if my son had kidney problems also extra stress is not good on her kidneys. Am I terrible for keeping this on the lowdown until the next sonogram to see if it fixes itself?