What is the major legal and philosophical problem with "wrongful life" cases?

The major legal and philosophical problem with "wrongful life" cases is "h ow to measure damages".

In a case for 'wrongful life', the offended party which is usually a newborn child brings an activity, for the most part against a doctor, asserting that some careless activity has caused the offended party's life, say by not illuminating the parents of the probable outlook that their kid would be conceived with severe imperfections.