Best-selling author Cecelia Ahern, 28, the daughter of former Taoiseach (Prime Minister) Bertie Ahern, is expecting her first child.

The beautiful writer and her partner,Dave Keoghan, an actor and former Olympic hopeful in hurdling, are thrilled with the news and hope to welcome their first child in December.

"It is with great joy that Dave Keoghan and Cecelia Ahern confirm that they are expecting their first child," the couple said.

The child will be the third grandchild for Bertie and Miriam Ahern and follows the birth of twins Jay and Rocco to Cecelia's older sister Georgina and her husband, singer Nicky Byrne from Westlife.

Ahern is the author of the hit book "P.S. I Love You," which she wrote in 2002 when she was just 21.

It was published in 2004, and was the No. 1 bestseller in Ireland, the U.S., Britain, Germany and Holland and was sold in over countries.

The book was made into a film starring Hilary Swank and Gerard Butler and was released in the U.S. in December, 2007.

More recently, Ahern co-created and produced the ABC half-hour comedy show, "Samantha Who?""

Samantha Who?," which stars Christina Applegate, is about a woman who is the victim of a hit-and-run incident.

Nine days later, she wakes from a coma with retrograde amnesia, leaving her to rediscover her life, her friendships and her family.

The series is based on the question that if you start life all over again with fresh eyes and armed with the knowledge of who you once were, can you change?