The couple, who married in Italy in 2012, are said to be 'enjoying the news', before officially confirming they're expecting.
"Right now they are just enjoying the news for themselves," a friend told Us Weekly. "They just want a happy baby."
Meanwhile, RadarOnline report that the actress is due to give birth in April.
"Jessica is at least three months pregnant. And she's due in April," a source told the site.
Last year, JT spoke of his love for his wife on Ellen DeGeneres's US chat show.
"Every once in a while I can catch a glimpse of her when she doesn't see me looking, and I have this moment where I'm like, 'If you never make a good decision…if you only make bad decisions for the rest of your life, you made one really good decision,'" he told her.
Congrats to them both!