Cystic fibrosis is a hereditary disease that causes certain glands to produce abnormal secretions, resulting in tissue and organ damage, especially in the lungs and the digestive tract. Cystic fibrosis is the most common inherited disease leading to a shortened life span among white people in the United States. It occurs in about 1 of 3,300 white infants and in 1 of 15,300 black infants. It is rare in Asians. Cystic fibrosis is equally common in boys and girls. Cystic fibrosis results when a person inherits two defective copies (mutations) of a particular gene. This gene controls the production of a protein that regulates the transport of chloride and sodium (salt) across cell membranes. Worldwide, about 3 of 100 white people carry one defective copy of the gene; thus, they are carriers but they themselves do not get sick. About 3 of 10,000 white people inherit two defective copies of the gene; thus, they develop cystic fibrosis. In these people, chloride and sodium transport is disrupted and dehydration and increased stickiness of secretions occur. The only risk factor known to increase the risk of having a child with cystic fibrosis is to have a family history of the disease.

CF is entirely genetic, according to my source 1 in 25 carry the gene that causes it, both parents need to carry the gene in order to pass a full blown case to their young (though offspring can still be a carrier, even if one parent carries the gene), the following is from the link: http://www.geocities.com/HotSprings/2677/CF.HTM "Cystic Fibrosis is developed when a person inherits the genetic fault which causes CF from both parents. The way in which our bodies develop is determined by pairs of genes. We inherit one gene of each pair from our mother, and the other from our father; which ones, being determined entirely by chance. About one-in-25 of the population is a carrier of the faulty gene which can cause CF in their children. CF carriers are completely healthy because they also have one normal gene which overrides the defective "CF gene. If both parents are carriers of a defective "CF gene", any child they have stands a one-in- four chance of having CF (if they inherit a defective gene from each parent); a one-in-two chance of being completely healthy but a carrier (having inherited a faulty gene from one parent and the normal gene from the other); and a one-in-four chance of being total]y unaffected (having inherited normal genes from both parents). In 1989 scientists discovered the faulty gene which causes CF and it is now possible to offer prospective parents a simple mouthwash test - or "screen" - to see if they are carriers. Specialist genetic counselling is also available for couples who both carry the gene to help them understand the chance of their having a baby with the disease, and also to explain decisions they will have to make before a pregnancy. Screening is particularly important for people who are either related to someone with CF or a known CF carrier because they are more likely to carry the gene. Their partners should also be tested." So yes there is a risk factor, it is dependant on whether you and your partner are carriers, trouble can be avoided by testing. If you are a carrier you can avoid having children with CF by ensuring your partner isn't a carrier, but you can't guarantee that your child won't be a carrier, even if your partner isn't one. Hope this helps!