The sister of Guardian Angels (search) founder Curtis Sliwa (search) gave birth to twins Tuesday, just three days shy of her 57th birthday.

Aleta St. James, who became pregnant by in-vitro fertilization, and her newborn son and daughter are doing well, said Maria Sliwa, the babies' aunt.

Francesca, who weighs 5 pounds, 12 ounces, and her brother Gian, who weighs 5 pounds, 3 ounces, were delivered by Caesarean section at Mount Sinai Medical Center (search). They are in excellent health, said Dr. Jonathan Scher, who delivered the babies.

St. James, a motivational speaker who helped her brother set up the crime-fighting group in the 1970s, said earlier this week that it's never too late to become a mother.

"You are never too old," she said. "It's just in your mind."