Hilary Duff  sunglasses pilates pregnant flip flops purse wave spandex

Determined to keep her pre-baby bod in tip-top shape, Hilary Duff headed to her weekly Pilates and Piloxing class, before stopping to refuel at Chipotle, on Tuesday.

The 24-year-old mommy-to-be got to flaunt a growing baby belly in her Halloween costume this year, opting for a "bank robber" theme with hubby Mike Comrie.

The couple attend a party at pal Ashley Tisdale's pad, after which Duff later Tweeted: "BTW had so much fun @ashleytisdale Halloween shindig last night! Thanks for having us! I swear we didn't steel anything ;) xxx".

The Beauty and the Briefcase star shared a Twitpic of the jailbird costumes with the caption, "We're gunna take you for allllll u got!!!". Check 'em out, after the jump ...