House Of Cards actor Sebastian Arcelus and his Broadway star wife Stephanie J. Block are preparing to become first-time parents.

The Tony Award nominee announced her pregnancy during an interview on Sirius Xm's On Broadway radio programme on Monday (04Aug14), and the show's host, Seth Rudetsky, took to to share the news with her fans.

Posting a photo of Block showing off her baby bump in a flowing dress, Rudetsky wrote in the caption, "Breaking news!!! @StephanieJBlock 4 months to go til #BabySebOrSteph".

Arcelus and Block, who co-starred in the hit Broadway shot Wicked, tied the knot in 2007.