"We are thrilled to announce that Tammy is pregnant, and expecting our twins sometime around this fall," they said in a joint statement on Etheridge's official Web site. "To answer the obvious question: We used an anonymous donor from a bank."
The women noted the twins will be their first children since their 2003 wedding in Malibu, Calif., but it is "not our first time mothering together."
Etheridge has a daughter and a son from her previous relationship with Julie Cypher. Both children were conceived with sperm donated by rocker David Crosby.
Etheridge, who underwent chemotherapy after being diagnosed with breast cancer in 2004, will be the speaker at Boston's Berklee College of Music's graduation ceremony May 13 and receive an honorary doctor of music degree.