Sienna Miller’s brood just got bigger.

The 44-year-old actress has given birth to baby No. 3, welcoming her second child with boyfriend Oli Green.

She revealed the news in an interview with E! , telling Will Marfuggi, “It’s happened. I have a tiny baby next door.”

“It feels like stringing sentences together is a bit challenging,” she added playfully. “I’m on very little sleep but I’m madly in love with my baby.”

Sienna Miller (pictured above in December 2025) and boyfriend Oli Green’s second child together has arrived. Gareth Cattermole/Getty Images for BFC

The little one is baby No. 3 for the actress (pictured above on March 12).…