The former Newcastle Knights forward - who suffered a spinal chord injury and was left quadriplegic - previously spoke of his hopes of one day having a baby.
"One of the first things Alex wanted to know after the accident was whether we could have kids one day, because he didn't want to miss out on that," Teigan previously said.
"So we went to see a fertility specialist and it seems there's a great chance, because he still creates sperm."
Teigan, 24, shared a snap of the happy family which she captioned: "When 2 became 3."
Alex proposed to his long-term partner from his hospital bed just days after suffering the injury and vowed to be on his feet when they married.
He kept his promise when they wed in the New South Wales Hunter Valley last year.
