Hi,
It is a good question. Kidneys do swell up during pregnancy as a result of increased work it has to do.
The good news is, it is purely physiological ! Hence, you need to do nothing to correct it.
If you have
kidney stone, it depends on where it is and how big it is. If it is small and non obstructing, it may pass off by itself.
Next Steps
Do visit a urologist prior to conceiving. That will help in comprehensive planning for the stones, if any.
Regards.