The Bible and Designer Babies
The term 'designer babies' is currently used by tabloids to refer to babies created using PGD. The process involves discarding embryos, so many Christians would use 'sanctity of life' teachings to argue against this - Do not kill, that humans are made by God, in His image, they are the temple of the Holy Spirit, God has a plan for every unique human individual, whom he knows and loves etc.
There are also concerns about the value judgments being made. If you use PGD to prevent genetic disorders or Downs Syndrome, this can lead to discrimination. By destroying embryos with Downs Syndrome, many Christians feel you are making a judgment about all people with Downs Syndrome. Have a look at biblical teaching on disability.