Below is an instruction from Human. Write a response.
    ### Instruction:
    What causes Urine Blockage in Newborns ?
    ### Response:
    Many types of defects in the urinary tract can cause urine blockage:
                
- Vesicoureteral reflux (VUR). Most children with VUR are born with a ureter that did not grow long enough during development in the womb. The valve formed by the ureter pressing against the bladder wall does not close properly, so urine backs uprefluxesfrom the bladder to the ureter and eventually to the kidney.
    