Beatie, 34, who kept female reproductive organs when he legally became a man 10 years ago, confirmed the birth to the magazine.
The baby, conceived through artificial insemination using donor sperm and Beatie's own eggs, was born on June 29 and Beatie and the baby are "healthy and doing well," People reported.
"The only thing different about me is that I can't breast-feed my baby. But a lot of mothers don't," People quoted Beatie as saying. He has had his breasts surgically removed.
He told the magazine that contrary to published reports, the baby was not delivered by Caesarean section, but no other details about the birth were given.
The thinly bearded Beatie told "The Oprah Winfrey Show" in April he began his sexual transformation about 10 years ago when he began taking testosterone treatment and had surgery to remove mammary glands and flatten his chest.
Upon deciding to have a child about two years ago, he halted his bimonthly hormone injections and resumed menstruating.
Beatie's wife, Nancy, 46, whom he married five years ago, was unable to conceive because of a prior hysterectomy. Otherwise, he has said, "I wouldn't be doing this." His spouse has two grown daughters by a previous marriage.
She said on Oprah's show their parental roles would be fairly traditional despite his transgender status. "He's going to be the father, and I'm going to be the mother," she said.
The couple, who operate a T-shirt printing business in Bend, Oregon, are legally married and he is recognized under Oregon state law as a man.
Update November 14, 2008: Thomas Beattie is pregnant again! The new baby is due on June 12, 2009.
