Her hesitation gone, Ms. Palin glowed with maternal pride. “Sarah was absolutely ecstatic,” said a friend, Marilyn Lane. After months of reflection and prayer, friends say, the Palins, who are Christians, had come to believe God had chosen to send them Trig.

Later that day, Ms. Palin sent an e-mail message to her relatives and close friends about her new son, Ms. Bruce said. She signed it, “Trig’s Creator, Your Heavenly Father.”

“Many people will express sympathy, but you don’t want or need that, because Trig will be a joy,” Ms. Palin wrote. She added, “Children are the most precious and promising ingredient in this mixed-up world you live in down there on Earth. Trig is no different, except he has one extra chromosome.”