"We finally know the sexes of these sweet little children coming into the world -- we've seen pictures of them," Quaid announced at his 5th Annual Dennis Quaid Charity Weekend in Austin. "One of them was a boy and one of them was a girl."
The couple announced last month that they were using a "gestational carrier," a woman who carries a baby conceived by another couple's sperm and egg, who started her pregnancy around that time, People Magazine reported Monday.
The twins are supposed to be delivered sometime around Thanksgiving.
"I'm over the moon," Quaid told People. "We are both so thrilled and excited. This is something we've wanted for some time."
Quaid already has one teenage son with actress Meg Ryan, his ex-wife.
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