Meiosis is a critical molecular process whose completion (for eggs) results in a fertilized

Meiosis is a critical molecular process whose completion (for eggs) results in a fertilized egg. It is imperative that the genetic re-assortment occurs with little to no error, as errors may result in an un-viable pregnancy or miscarriage. Scientists involved in vitro fertilization perform genetic screenings to minimize the chance for miscarriage.
 
What ethical issues arise when artificially performing genetic screenings during in vitro fertilization?

Define bio-ethics and use 1 scientific reference to support your position on this frequently debated topic.