Washington - Former Republican vice-presidential nominee Sarah Palin's daughter, Bristol, has given birth to a son, People magazine reported Monday.

Bristol, 18, gave birth to a 3.3-kilogram baby boy in Palmer, Alaska on Sunday, the magazine quoted Palin's aunt, Colleen Jones, as saying.

The baby has reportedly been named Tripp Easton Mitchell Johnston.

"We think it's wonderful. The baby is fine and Bristol is doing well. Everyone is excited," Jones was quoted as saying.

The baby's father, Levi Johnston, is an apprentice electrician and former high school hockey player. Bristol is currently completing her high school diploma through correspondence courses in Wasilla, Alaska. The couple plans to marry in 2009.

Bristol's pregnancy made news during the US presidential campaign as it was revealed shortly after Alaska Governor Palin was picked as Republican candidate John McCain's running mate.

In a statement in September, Palin and husband Todd said: "Our beautiful daughter Bristol came to us with news that as parents we knew would make her grow up faster than we had ever planned ... We're proud of Bristol's decision to have her baby and even prouder to become grandparents."

The Palins said that Bristol and "the young man she will marry are going to realize very quickly the difficulties of raising a child, which is why they will have the love and support of our entire family."

Palin, a mother of five, is an outspoken opponent of abortion.