From the New York Times:
... During her affair with Cooper she became pregnant and had an abortion, according to the autobiography “As I Am” (1988), written with Richard DeNeut. “If I had only one thing to do over in my life,” she wrote, “I would have that baby.” Eager to have children, she married Dahl in 1953, even though she did not love him then, she wrote in her autobiography. A former R.A.F. fighter pilot who became a renowned writer of often darkly humorous children’s books (“James and the Giant Peach,” “Charlie and the Chocolate Factory”), Dahl took control of Ms. Neal’s life. After their four-month-old son, Theo, was left brain-damaged when his pram was crushed between a taxicab and a bus on a New York street in December 1960, Dahl decided that they would move to the village of Great Missenden in England. Two years later, their eldest daughter, Olivia, who was 7, died of measles encephalitis, perhaps for want of sophisticated medical care that would have been available in a big city.