A 66-year-old pregnant British woman has defended her right to have a baby at her age.

Elizabeth Adeney, who is believed to be about eight months pregnant after undergoing fertility treatment, is expected to become Britain's oldest mother when she gives birth.

The divorcee has told reporters that her pregnancy is her own business.

"I don't have to defend what I have done. It's between me and my baby and no one else," she told the newspaper.

"It's a very private thing and I don't expect anyone else to understand it.