Hello and welcome to our family.
Prednisone can affect fertility as it has been known to reduce sperm count. Methotrexate can also reduce sperm count. I dont know how long you have to be on these drugs for them to affect sperm count or what dosage would affect the count. Speak with your urologist to get more definitive answers. I wish you the best and hope that you have a healthy and happy baby.
Peace and Blessings