Scarlett Johnasson’s engagement to Ryan Reynolds could be followed by another big announcement, because the actor is desperate for kids.

The couple made the big announcement on Monday a year after they hooked up, following 31-year-old Reynolds' split from singer Alanis Morissette.

And he hints he will be encouraging his 23-year-old fiancee down the aisle and into the maternity ward in a hurry.

Reynolds says, "I do want a child at some point.

"I feel like I need to fulfil the genetic paradigm, the destiny of it all."