Husband is on prozac, soma, zenzedi (stimulant for adhd) and valium. we are looking to conceive. will these medications affect his sperm to cause birth defects?

Maybe/not. At least in theory men get a pass on many exposures when related to conception/birth defects. Sperm are generated in the millions and created continuously. Any fraction that are altered tend to be poor swimmers & less likely to make it through the distance to conception than the healthy ones. Women don't get that break as eggs remain subject to any exposure and are limited in number.