Christina Applegate and Martyn Lenoble

Christina Applegate and her fiancé Martyn Lenoble are expecting their first child, her rep confirms to

Christina Applegate is engaged

Applegate, 38, and Lenoble, 41, the former bassist for Porno for Pyros, got engaged on Valentine's Day 2010 after dating for two years. No date has been set for the wedding.

In 2008, the Samantha Who? actress underwent a double mastectomy to treat breast cancer, which has been in full remission since August 2008. She'll be next seen in the romantic comedy Going the Distance, alongside Drew Barrymore and Justin Long.