I feel you it can change after birth they will do an ultrasound a few days after birth you will then meet with a Uroligist and depending on what the ultrasound looks like it will be your only appointment if it hasn’t then baby will get put on antibiotics and follow up ultrasound and a few tests and depending on one of them they will either do surgery or just monitor I do recommend having a thermometer that takes temp rectally because it’s more accurate and fever can indicate infection if you ever have anymore questions just message me and the surgery wasn’t that long
Honestly I can’t remember we have done so many ultrasounds and they did a few tests and there are different reasons that it could cause it like reflux or a kink which was my sons case
My son has it of his left kidney he had stage four it got progressively worse he had surgery last January and it’s getting better my cousins son fixed itself and my friends son may need a third surgery