Uma Thurman bikini pregnant ? ; See her popping belly on a romantic cruise with fiancé Arki Busson

She's known as one of Hollywood's most glamorous and statuesque stars, but Uma Thurman certainly let her guard down during a luxury cruise in Corsica.

The actress caught onlookers by surprise as she revealed a rather pronounced tummy while frolicking aboard a yacht in a skimpy bikini with her new fiancé Arpad 'Arki' Busson this week.

While her expanded waistline is quite likely the result of a little lunch-time indulgence, there's no doubt it will set off whispers of a pregnancy for the 38-year-old.

Off guard: Uma Thurman surprised onlookers with a mystery bump while holidaying in Corsica this week

After all, it does coincide with her recent engagement to the Swiss multimillionaire. 

The pair announced their plans to wed in the personal columns of The Times last month, followed by an engagement party of stellar proportions.

A marquee in the garden of Arki's £10million Kensington home played host to an array of stars, including Elton John, Sting, Sir Philip Green, Jemima Khan, Claudia Schiffer and Damien Hirst. 

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Smooth sailing: The newly engaged actress soaked up the sun aboard a luxury yacht 

She met the 45-year-old financier and philanthropist at a dinner party in Milan last summer, having just split up from her partner of three years, the New York hotelier Andre Balazs. 

The star had also endured three years of being stalked by a psychiatric patient in her native New York, and prior to that the painful collapse of her marriage to fellow actor Ethan Hawke, with whom she has a daughter, Maya, nine, and a son, Levon, six. 

Arki's relationship with Uma, who found fame in films Dangerous Liaisons and Pulp Fiction, follows nine years with the Australian model Elle Macpherson, with whom he has two sons, Flynn, ten, and Cy, five.