Savannah Miller, 47, has revealed that her sister Sienna's recent pregnancy inspired her own decision to have a fourth child. Savannah, a fashion designer, showcased her baby bump during a babymoon with her husband, James Whewell.

In March, Savannah shared her joy at being pregnant concurrently with her younger sister, actress Sienna Miller, 44. Sienna welcomed her second child with boyfriend Oli Green, 29, at the end of April. Savannah admitted that her own pregnancy was intentional, stating to Hello! magazine, "If she's doing it again, at least I won't be in the trenches on my own. I'll join her… if I should be so lucky."

Savannah, who is already a mother of three to Moses, 21, Lyra, 18, and Bali, 14, with her ex-husband Nick Skinner, spoke about the societal view of women having children later in life. "There's a very strong narrative against women doing things... It frustrates me immensely, because if it were a man, the question wouldn't arise; it doesn't enter people's heads," she said. "If it's biologically possible, then clearly it's totally fine."

Her announcement in March included photos of her bump, with the caption: "Our longed for miracle baby is joining gang in August!". She added, "To be able to relive the magic of pregnancy, with Jim, who is the most deserving and dedicated dad already to my three, is a profound and phenomenal gift... Now I know how brief it all is, on the cusp of my firstborn's 21st birthday, I hope to be able to slowly savour the innocence and wonder in every minute... To be doing it all over again at the same time as my sister is the most delicious cherry on the icing on the cake."

Savannah's babymoon comes as Sienna Miller recently shared the first photos of her newborn and her two-year-old daughter with Oli Green. The actress posted a series of images documenting their first few weeks as a family, captioned "Adulting." The photos included Sienna cuddling her newborn in hospital, though the baby's sex and name have not yet been revealed. She also shared a picture of her toddler daughter's curly hair.

Sienna, now a mother of three, also shares daughter Marlowe, 13, with ex-partner Tom Sturridge. She announced her third pregnancy in December at the Fashion Awards. In May, she mentioned on The Tonight Show With Jimmy Fallon that she was surviving on "very little sleep" and finding it challenging to string sentences together after returning to work just three weeks postpartum. She described a difficult transatlantic flight with her toddler and newborn, noting it was tougher than managing her teenage daughter.