Ventriculomegaly (enlargement of the fluid filled spaces in the brain) with a measurement in the lateral ventricle of 10 mm can be normal if the ventricle does not continue to enlarge and no other abnormalities are found.
The size of the ventricle is usually followed using more ultrasounds to evaluate for any continuing change in size. If the size of the ventricle stays stable, your baby is unlikely to have any problems.
You should continue to discuss the situation with your Obstetrician or Perinatologist.