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Megan Fox gave birth to her first child with Brian Austin Green on Sept. 27, but she kept the news under wraps until a few weeks later. Green said he believes they were able to hide it from the public for so long because Reese Witherspoon welcomed her newborn baby on the same day.

Speaking with Ryan Seacrest on his Los Angeles-based radio show Tuesday, Green said that he and Fox sneaked into a hospital in the early morning "and nobody knew, and we heard that Reese was at her place and had had a baby. And we got out of the hospital and nobody knew, and we got home and thought, 'this is unbelievable, 'cause we weren't expecting to be able to get away with it.'"

RELATED: Megan Fox, Brian Austin Green Welcome Baby Boy

Fox announced on Facebook on Oct. 17 that she and Green had welcomed a son, Noah Shannon Green. Witherspoon and her husband, Jim Toth, also had a son, whom they named Tennessee.

Green stars in the new TBS comedy "Wedding Band," premiering this Saturday night.