Baby on board!

A pregnant Lily Aldridge was all smiles at the American Beauty book launch in NYC Thursday.

Clad in a floor-length Proenza Schouler maxi dress and towering Alaia sandals, the fist-time mommy to be showed off her growing baby bump.

PHOTOS: Sexy supermodel moms

Back in December, the Victoria's Secret model announced that she and husband Kings of Leon rocker Caleb Followill are expecting their first child together.

PHOTOS: See the couple's stunning wedding pic

The couple, who wed in May, told Us Weekly in a joint statement, "We are thrilled to announce that we are expecting our first child together. We can't wait to meet the new addition to our family."

PHOTOS: Hot! Lily Aldridge flaunts her assets on VS runway

Aldridge, 26, isn't the only Victoria's Secret Angel to have a baby on board.

Alessandra Ambrosio is currently pregnant with her second child with fiance Jamie Mazur (they're parents to 3-year-old Anja), and fellow Brazilian Adriana Lima her Serbian basketball player hubby Marko Jaric are also expecting a brother or sister to daughter Valentina, 2.

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