Sienna Miller makes admission about filming NSFW scenes whilst six months pregnant

Sienna Miller has opened up about one of the more challenging aspects of making her new divorce drama, War, revealing that she was six months pregnant when she filmed an intimate scene.

Miller, 44, was expecting her third child while working on the new Sky and HBO legal series, in which she stars opposite Dominic West.

Miller plays Hollywood actress Carla Duval, whose marriage to tech billionaire Morgan Henderson, played by West, collapses into a bitter and increasingly public divorce battle.

Her pregnancy was not written into the storyline, meaning the production team had to find ways of concealing her growing bump as filming progressed.

But while costumes and carefully chosen camera angles could disguise her pregnancy in many scenes, Miller admitted there was one particular part of the production where that became considerably more difficult.

Sienna Miller stars alongside Dominic West in their new show, War (HBO)

Speaking about filming a sex scene while six months pregnant, she described the experience as among the ‘hardest’ moments she faced while making the series.

Miller explained that shooting intimate scenes can already be an unusual experience for actors, with carefully choreographed movements and crew members surrounding them on set.

She described the scene she filmed with Archie Renaux, who plays lawyer Johnny Warren in the show: “Trying to do a love scene while six months pregnant with Archie Renaux and he was terrified and there was a bump! And he had to lower me on to a table and I was heavy.”

Miller added: 'I must of been about six and a half, seven months and I was trying to feel sexy and not vom.”

West, meanwhile, joked about facing challenges of his own during the production, quipping that in his case he was ‘just old’.

Miller was around three months pregnant when production began and was approaching her due date by the time filming finished.

She has admitted that the experience left parts of the shoot feeling hazy.

“I was very newly pregnant when I got this script and very, very pregnant when we finished filming it, so the whole thing is a bit of a blur,” she confessed.

Costume designer Ian Fulcher Price also had to continually adapt Carla's wardrobe to accommodate Miller's changing figure without revealing her pregnancy on screen.

“We built it into the designs and the cuts,” he told the Television Academy.

Miller and West have known each other for a long time (Photo by John Nacion/Variety via Getty Images)

Early episodes made use of oversized suits, while later scenes relied on empire-line waists and darker clothing to help conceal her bump.

War centres on the spectacular breakdown of Carla and Morgan's marriage and the legal battle that follows, drawing two rival London law firms into the dispute.

Created by Lupin and Hijack writer George Kay, the eight-part drama also stars Phoebe Fox, Nina Sosanya, Nick Mohammed, Archie Renaux and Celia Imrie.

For Miller, Carla also offered an opportunity to play against her own instincts.

She has described the character as narcissistic and calculating, saying she enjoyed switching off the ‘people-pleasing’ side of her personality.

It was also a reunion of sorts for West and Miller, as they first worked together when Miller was 21, appearing in a West End production of Shakespeare's As You Like It.

Miller has described the experience as ‘incredibly bonding’, and the pair remained fond of one another despite not regularly crossing paths in the years that followed.

That familiarity proved useful when they were cast as a married couple whose relationship has disintegrated.

“It’s dead easy to be in love with Sienna; you don’t really have to act any of that,” West previously told Radio Times, adding that creating the hostility between their characters was the more difficult task.

Miller has similarly said their friendship made playing an acrimonious couple surprisingly enjoyable.

“I think the more you love someone off screen, the more fun it is to hate them on screen,” she told PEOPLE at the show's New York premiere. “So we had a lot of fun being this couple.”