is an autosomal recessive disease. This means that it is passed down from parents to their children, but that the parents don't necessarily have to have the disease themselves. Each parent has two sets of chromosomes (one each inherited from their own parents). Each chromosome contains genes, which can later become proteins manufactured in the body's cells. The particular gene that is affected in cystic fibrosis controls the production of a type of electrolyte transporter on the surface of certain cells. In order for a person to have cystic fibrosis, they need to have two mutated copies of the gene, not just one.
In other words, your child inherited one defective gene from both you and your husband. Both you and your husband have one mutated version of the gene and one normal version of the gene. The chances of your child inheriting both of the mutated genes is 1 in 4. This is also the chance of all of your children developing the disease; having one child with cystic fibrosis does not change this probability in the future. For further information, you can talk with your primary care provider or seek out a genetic counselor.