We haven't heard so much as a squeak from the couple since they welcomed their first child on the weekend, but E! News has revealed Sienna and Tom had a baby girl called Marlow.
There's no official word as yet, though. The engaged pair are notoriously private when it comes to their relationship.
"I'm under strict instructions not to say anything as it would completely defeat the point of everything I've tried to achieve in the last eight years," Sienna told British Vogue in April when discussing her pregnancy.
The 30-year-old also revealed she'd taken up yoga to calm her pregnancy nerves.
Sienna and Tom have been together for over a year, getting engaged in December 2011 when Tom proposed to his lady in Paris.