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.”

However, she did not reveal when she gave birth, the baby’s name or sex.

The couple also shares a daughter, 3, but have yet to reveal the toddler’s name.

Miller, additionally, is the mother of daughter Marlowe, 12, whom she co-parents with ex-fiancé Tom Sturridge.

The former couple broke up in the summer of 2015 after four years together, and Miller briefly moved on with businessman Lucas Zwirner before going public with Green, 29, in late 2021.

The duo has primarily kept their romance out of the spotlight over the years.

The model, however, spoke out to defend the pair’s age gap in December 2023.

“I would imagine it would be complicated for anyone to get their head around, but there’s been nothing but love and joy,” Miller insisted to Vogue at the time.

While acknowledging she “might want to be with someone older,” the Golden Globe nominee said it isn’t possible to “legislate on matters of the heart” and she “certainly [has] never been able to.”

Green, notably, did have to “work hard” to persuade his now-partner to go on a date due to their age difference.

Miller confessed she initially thought their connection was “absurd” and wouldn’t “go anywhere.”

She noted to Harper’s Bazaar the following year that “there is a difference in the way that generation of men respect women.”

“He is very wise and well-adjusted, but I do believe it’s also that generation,” Miller speculated in June 2024. “They have grown up with a slightly more level playing field.”

Most recently, the “Anatomy of a Scandal” star opened up to Grazia in March about how “the idea of an older woman with a younger man … is still fetishized rather than normalized.”

She quipped, “There’s a disparity there that I would love to see disappear.”