Sienna Miller Breastfeeds Newborn Backstage at Fallon

took to Instagram with candid footage of her breastfeeding her newborn baby backstage at The Tonight Show With on Friday.

The British actress, 44, returned to work with her glamorous chat show appearance just three weeks after welcoming the tot with boyfriend Oli Green, 29.

The couple are already parents to a two-year-old daughter, while Sienna is also mum to daughter Marlowe, 13, whom she shares with ex-fiancé . 

In the clip Sienna could be seen feeding the baby while she sat in the make-up chair before passing the little one to Oli who cooed over the newborn, whose gender or name the couple have not made public.

The new mum was later surprised with a Tonight Show baby grow, before she slipped into a figure-hugging yellow dress and headed onto the set.

Asked by the host which of her children are tougher to look after, she said: 'I would have said the teenage girl would be harder to juggle until the transatlantic flight I took yesterday with the toddler and the newborn. The toddler now wins hands down. It was an absolute disaster. There's no negotiating,'

She added: 'I got to the immigration line and just broke down.'

Sienna announced that she had welcomed her second child with Oli, telling E! News last week : 'It's happened. I have a tiny baby next door. It feels like stringing sentences together is a bit challenging...

'I'm on very little sleep but I'm madly in love with my baby.'

She is currently blazing the promo trail with her latest movie, Jack Ryan: Ghost War, and announced the sweet news to the publication in her promotional interview.  

Sienna announced her third pregnancy by revealing her blossoming bump at the star-studded  in December. 

It was only right for the actress to make her revelation with a statement look on the blue carpet outside the Royal Albert Hall in London. 

And it is not the first time Sienna has used the red carpet at a fashion event to announce she is . 

Back in September 2023, Sienna  

The actress walked the red carpet at London's Theatre Royal Drury Lane in a Schiaparelli puffball skirt and a cropped shirt which showcased her baby bump.

Previously speaking about Oli, Sienna told Harper's Bazaar: 'I didn't expect to take it seriously and then quite quickly, I fell in love. 

'I wasn't like, "I'm gonna get a younger boyfriend." It was more, "F***! Why are you young? That's so annoying."  

'There is a difference in the way that generation of men respect women. It's specific to him, he is very wise and well-adjusted, but I do believe it's also that generation.

'They have grown up with a slightly more level playing field. I see it in his female friends as well as in the men.'