Infertility affects both men and women. At least 97% of men with cystic fibrosis are infertile, but not sterile and can have children with assisted reproductive techniques.  The main cause of infertility in men with CF is congenital absence of the vas deferens (which normally connects the testes to the ejaculatory ducts of the penis ), but potentially also by other mechanisms such as causing no sperm , abnormally shaped sperm , and few sperm with poor motility .  Many men found to have congenital absence of the vas deferens during evaluation for infertility have a mild, previously undiagnosed form of CF.  Around 20% of women with CF have fertility difficulties due to thickened cervical mucus or malnutrition. In severe cases, malnutrition disrupts ovulation and causes a lack of menstruation . 
Prednisone is a drug that belongs to the corticosteroid drug class, and is an
anti-inflammatory and immune system suppressant. It's used to treat a variety of diseases and conditions, for example: inflammatory bowel disease (Crohn's
disease and ulcerative colitis ), lupus , asthma , cancers , and several types of
Common side effects are weight gain , headache , fluid retention, and muscle weakness . Other effects and adverse events include glaucoma , cataracts , obesity , facial hair growth, moon face, and growth retardation in children. This medicine also causes psychiatric problems, for example: depression , insomnia , mood swings , personality changes, and psychotic behavior. Serious side effects include reactions to diabetes drugs , infections, and necrosis of the hips and joints.
Corticosteroids like prednisone, have many drug interactions ; examples include: estrogens , phenytoin ( Dilantin ), diuretics, warfarin ( Coumadin , Jantoven ), and diabetes drugs . Prednisone is available as tablets of 1, , 10, 20, and 50 mg; extended release tablets of 1, 2, and 5mg; and oral solution of 5mg/5ml. It's use during the first trimester of pregnancy may cause cleft palate . This medicine is secreted in breast milk and can cause side effects in infants who are nursing . You should not stop taking prednisone abruptly because it can cause withdrawal symptoms and adrenal failure. Talk with your doctor, pharmacist, or other medical professional if you have questions about beta-blockers. Talk with your doctor, pharmacist, or other medical professional if you have questions about prednisone.
If you notice other effects not listed above, contact your doctor or pharmacist. In the US -Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088. In Canada - Call your doctor for medical advice about side effects. You may report side effects to Health Canada at 1-866-234-2345.