Thank you for your consult at DoctorSpring.com,
Mild to moderate hydronrphrosis on one side is a frequent phenomenon during pregnancy. It rarely requires surgery or termination of pregnancy.
You need to see the size and function of the kidney before taking a decision. As we can't do the functional assessment if that kidney during pregnancy, we can't say any thing.
As far as the termination of pregnancy is concerned u don't need to worry as it is not really required. Why did you get chest x ray done. You could have presented the original ultrasound report rather. Get urine culture test done and see whether there is any urine infection now.
Hope this helps, please feel free to discuss further.