Ms Patteson successfully applied to the Supreme Court to have his sperm removed just one day after his death, and the court acted quickly as the tissue becomes unusable after 24 hours, the Daily Mail reported.
However Mr Deane's mother said she is unsure her son would be happy with his fiancée's decision.
"I believe that Tony would not have wanted a child brought into this world if he could not be there to raise it," Mrs Deane said.
She has also said that the family would fight any action that would see her son's sperm be used to impregnate Ms Patteson.
Earlier this year Justice Martin Burns granted the request to remove the testicles but said another application must be made before the sperm was used.
He said this would give Ms Patteson the chance to think about whether she really wanted to go through with her pregnancy.