Life's a circus for the Duchess of Cambridge! For her 31st birthday, pregnant Kate Middleton came out of hiding to celebrate the milestone with her family -- hitting London's Royal Albert Hall the evening of Wednesday Jan. 9. In one of the first photos of Kate in weeks, Kate, with her hubby Prince William, 30, beside her claps for entertainers in Cirque du Soleil's Kooza performance.

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A rep for St. James Palace previously told Us Weekly the expectant Duchess would be "spending her birthday privately," with another source predicting a "low-key" affair for Middleton. Instead, the Duke and Duchess were joined by her parents Carole and Michael Middleton plus siblings Pippa and James plus other friends and relatives -- were they were videotaped watching from the royal box with tense, rapt, overjoyed expressions.

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E! News reports that Kate and her mother Carole went into hysterics after one clown onstage bemoaned a stolen crown -- pointing to the crowd and asking, "Who has my crown?" During the intermission, the group retired to a private room on premises to celebrate the birthday girl.

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Accoring to E! the group had left by 10:45 p.m., with the royal couple retiring to their Kensington Palace home just across the street. Things are certainly looking up for the royal mom-to-be, who is now "safely in her second trimester now," a source told Us Weekly. After dealing with acute morning sickness that landed her in the hospital last month, Kate is now in the "honeymoon phase" of her pregnancy, a source tells Us. Read much more about Kate's pregnancy update in the new issue of Us Weekly, out now.

This article originally appeared on Kate Middleton Celebrated 31st Birthday at Cirque du Soleil Show With Prince William: Picture