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We have to say, we've never seen Hilary Duff as happy as she's been lately!

Seems like pregnancy is agreeing with Duff -- she was in a wonderful mood at pilates on Thursday morning. In sweats and a tee, Duff looked comfy and cute -- and the pregnancy glow doesn't hurt, either!

Hil, 24, is expecting a boy, and she recently said that this baby probably won't be her only one! Hil's hubby Mike Comrie comes from a large family, so they want several little ones!

As for names, Hil says she and Mike are considering more traditional names for their mini-man. Cute!