The Real Housewives of Orange County alum gave birth to Roman Scott McLaughlin on Tuesday.
"Baby Roman has captured our hearts and just like that our lives are forever changed," Lydia, 33, tells Us. "We are so grateful to now be a family of five."
The McLaughlins, who married in 2010, are already parents to sons Stirling, 5, and Maverick, 3.
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