“We are so pleased to introduce you to our new baby, Leonardo Ángel Charles Baldwin,” she wrote alongside a photo of her cradling her son.
“It was such a special day bringing him into this world.”
Her husband Baldwin, who also has daughter Ireland, 21, from a previous relationship, tweeted the news with a link to his wife’s Instagram photo.
The couple, who married in June 2012, announced in March 2016 they were expecting their third child together, less than a year after the birth of their son Rafael.
“Ireland, Carmen, Rafael, Alec and I are excited to share with you that we are going to have another addition to our family,” she wrote alongside a photo of her and her husband.
“A little boy coming this fall.”