The baby, named Solomon, is the first born to Robyn and husband Kody. Robyn has 3 children from a previous marriage.
"He's perfect and we couldn't be happier," Kody tells PEOPLE. "We are so thrilled."
The Browns, who are fundamentalist Mormons not affiliated with the Church of Jesus Christ of Latter-day Saints, moved from Utah to Nevada last year after police launched an felony bigamy investigation last year. In July, the Browns filed a federal lawsuit challenging the constitutionality of Utah's bigamy law.
(image via: http://www.people.com/)