The record for Britain's oldest women to give birth will be broken next month by 66 year old Elizabeth Munro, from Cambridge. It is thought that Ms Munro, who is single and a successful business woman, travelled to the Ukraine to become pregnant using donor eggs and IVF treatment.

In the UK, health trusts determine which women will be eligible for IVF treatment on the National Health Service (NHS), and factors limiting availability include the age of the woman. Not many trusts will consider providing NHS treatment for women over about 39 years old. However, some private clinics, which are not obliged to follow NHS guidelines, will offer treatment to women up to the age of 50, although it is rare for them to consider treating women older than this.

The news has reignited an ethical debate that began in 1994 when Professor Severino Antinori pioneered an IVF treatment using donor eggs to allow the current record holder, Patricia Rashbrook, to conceive at age 62. Advances in assisted reproduction have made it possible for women of almost any age to have children, although experts are divided about the extent to which it is ethically acceptable to extend motherhood. There is apprehension about the increased health risks to older mothers and their babies, and the increased chance of the child becoming an orphan before adulthood. There are also concerns over potentially increased costs incurred by the health system, as patients circumvent UK guidelines by travelling abroad for fertility treatment.

Professor Antinori has spoken out against the pregnancy, saying that he believes Ms Munro has left it too late for motherhood: 'I am shocked by the idea of a 66-year old giving birth. I respect the choice medically, but I think that anything over 63 is risky because you cannot guarantee the child will have a loving mother or family,' he told The Sunday Times newspaper.

Ms Munro, who is due to give birth next month by Caesarean section, claims she still feels 39 and is fitter than many women a third her age. Speaking to the Daily Telegraph newspaper, she said: 'It's not my physical age that's important - it's how I feel inside.' She added: 'I don't have to defend what I have done. It's between me, my baby and no-one else'.

Laurence Shaw, a consultant in reproductive medicine, believes that older women should be allowed to become mothers, provided they are fit enough to do so. 'The truth is that anybody might not survive to raise their children. Now life expectancy is 80 so is it not reasonable for someone to go through a process of fitness screening to decide whether they should have a child?' he told the Sunday Times.

Elizabeth Munro is not the oldest woman to become a mother: Omkari Panwar, from India, had IVF triplets at the age of 70 with her 77-year-old husband last year.