Thanks for your query,based on the facts that you have posted it appears that your husband has Oligospermia
the sperm count
being too low (0.45 millions /ml.) in a given situation there are no chances of natural pregnancy .
You have to get active motile sperm directly from the Testis by the method MiCRO TESE where sperms are picked up from seminiferous tubules of the testis and used for fertilization of female egg.
This is surgical procedure done under short general anaesthesia
by a infertility