"We are beyond thrilled to announce the birth of our daughter," Pratt captioned a picture of him and Schwarzenegger holding their newborn's hand. "We couldn't be happier. Both mom and baby are doing great."
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"We are extremely blessed," the 41-year-old actor continued the post.
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Pratt's "Guardians" co-stars congratulated the couple on the new addition to their family. Zoe Saldana commented, "Welcome to the world Lady Lyla! May your path be blessed with grace and joy always! We are so happy for you guys! Sending you so much love."
"So happy for you! And can't wait to meet her!" actress Karen Gillian said.
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Maria Shriver, mother to Schwarzenegger, also expressed her congratulations, saying she is "happy" Pratt gets "to experience being a girl dad."
This is Schwarzenegger's first child and Pratt's second. The actor also shares a 7-year-old son, Jack, with ex-wife Anna Faris.
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