Sienna Miller is expecting her second child!The actress was spotted with a baby bump while vacationing in Ibiza this week, according to photos obtained by ET. While spending time at the beach with friends, Miller donned a two-piece brown bikini that put her belly on full display.The star, 41, is already mom to a 11-year-old daughter, Marlowe, whom she shares with her ex, actor Tom Sturridge.ET has reached out to Miller's reps for confirmation.While the actress has yet to comment on the happy news, she was all smiles with her boyfriend, 26-year-old actor Oli Green, when the pair attended Wimbledon together earlier this summer.Oli Green and Sienna Miller at the 2023 Wimbledon Championships on July 9, 2023.Miller and Green were first linked in February 2022 after they were spotted out on a date in New York City.