Mary Cheney, the openly gay daughter of Vice President Dick Cheney and his wife, Lynne, is pregnant.
Mary Cheney, 37, and her partner of 15 years, Heather Poe, 45, are expecting a baby, said Lea Anne McBride, a spokeswoman for the vice president.
The baby is due in late spring.
"The vice president and Mrs. Cheney are looking forward with eager anticipation" to the arrival of their sixth grandchild, McBride said.
Mary Cheney was an aide to her father during the 2004 campaign and now is vice president for consumer advocacy at AOL.
McBride declined to elaborate on the circumstances of Mary Cheney's pregnancy.
Mary Cheney and Poe moved from Colorado to Virginia a year ago to be closer to the Cheney family.
Mary Cheney's openness about her sexual orientation had posed a dilemma for conservative activists who admire Dick Cheney's stance on many issues but consider homosexuality a sin.
As such, the news of her pregnancy drew a wide range of reactions.
Some Christian leaders voiced dismay, while a gay rights group seized on the opportunity to criticize the vice president, suggesting he now faces "a lifetime of sleepless nights" for serving in an administration that has opposed recognition of same-sex couples.