"Hayes Alba Warren: You sure know how to ring in the new year! You showed up a few days early but we couldn't be any happier. Your Mamma is the strongest woman I know ... you're so lucky to have her by your side. You have two amazing sisters who already adore you and I know you'll be thankful to have them guide the way," Alba's husband Cash Warren said in an Instagram post Monday.
"On your first day of life, I promise to love you, to cherish you, and to provide you with a sandbox full of dreams to explore. Welcome to the family my sweet baby Hayes! 12/31/2017."
Warren also included a photo of him holding his sleeping newborn, who is wearing a tiny, striped hat.
"Hayes Alba Warren 12/31/17 Best gift to ring in the New Year!! Cash and I feel so blessed. Haven and Honor are already obsessed with their new baby bro," Alba wrote on her own account, which also featured a photo of the infant. "#familyof5."
Warren and Alba have been married since 2008.
They are also the parents of 9-year-old Honor and 6-year-old Haven.
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