Mary Cheney, the lesbian daughter of former US vice-president Dick Cheney, is pregnant with her second child.

Cheney had her first baby, Samuel David, in 2007. She has confirmed that the new addition to her family is due in mid to late November.

Conservative and Christian groups questioned whether Ms Cheney and her partner of 17 years, Heather Poe, would make suitable parents.

Cheney played a key role on her father’s campaigns for the second-highest office in the land in 2000 and 2004.

The 40-year-old is also a vice president, of consumer advocacy at internet giant AOL.

Although she has been attacked by conservatives for raising children with another woman, Cheney has fought back.

She previously said: “Every piece of remotely responsible research that has been done in the last 20 years has shown there is no difference between children raised by same-sex parents and children raised by opposite-sex parents. What matters is being raised in a stable, loving environment.”