Pre-conception gene tests
Parents have been able to test their baby's genes for a while, but now they can do it before they even start trying to conceive.
Genetic carrier testing is a new procedure where both parents are checked to see if they're carriers.
Cystic fibrosis is just one of the disorders they look for, and with one in 25 people carrying the gene, the chances are higher than you would think.
Dr Mary Birdsall from Fertility Associates joined Mark Sainsbury, filling in for Paul Henry.