Leave it to chic Sienna Miller to turn her baby bump into a fashion accessory.

OK! NEWS: SIENNA MILLER COVERS BRITISH VOGUE AND TALKS PREGNANCY: IT'S EXCITING

Sienna attended Robert Pattinson's 26th birthday party dinner at the Gordon Ramsey restaurant at London's swank Claridge's hotel on Sunday. She looked incredibly fashionable and put-together in gray dress and metallic shoes.

OK! NEWS: SIENNA MILLER'S BABY BUMP REVEALED ON THE RED CARPET IN NYC

This is the first child for Sienna and boyfriend Tom Sturridge (who is best buds with Robert). The couple will welcome their bundle of joy in July.