DR PIPPA HAYES, a Devon GP, has a conscientious objection. She believes couples should restrict their families to two children - and says she would not help to provide fertility treatment for women who want to have exceptionally large families.

Hayes, who underwent sterilisation after the birth of her second son, despite wanting a daughter, believes that large families place an insupportable burden on the planet’s resources. She states her beliefs on the website of her Exeter-based practice.

This weekend she said she would formally decline to help certain patients.

“If a mother of four came to me and said, ‘Will you refer me for fertility treatment so that I can have a fifth baby’, I would say, ‘Sorry, this is something which is against my beliefs, but I suggest you go and see one of my partners’. I believe I would have a right to be a conscientious objector if it happened.”

She said that mothers of large families, such as the anti-abortion campaigner Victoria Gillick, would avoid consulting with her.

Hayes added: “If someone said to me, ‘Doctor, I have got two children, I am thinking about number three, what do you think?’ then I think it would be reasonable to discuss it. I would never obstruct anyone, however, because it is a free world.”

If the woman decided to conceive a third child naturally, Hayes would support her and give all the normal health advice such as taking folic acid supplements.

She said of her decision to sacrifice the chance of having a daughter: “I always knew two were the limit. That is all we are entitled to.

“I elected to have a female sterilisation a year or so after baby number two. I had no doubt it was a final decision. The question we always ask patients is, ‘What if your family is wiped out?’ but I don’t tend to think like that.

“I wanted a daughter in the first place but my lot was to have boys and I have got two lovely sons. My husband originally thought a nice big family was what he wanted, but he was happy to go along with my beliefs.”

Hayes is a member of the Optimum Population Trust, a campaign group that tells couples to “stop at two”. Membership of the group has doubled in the past 12 months to about 1,000 and it aims to double its membership to 2,000 this year.

This month an international group of scientists and academics is launching a campaign called Global Population Speak Out to publicise the “fundamental link between the size and growth of the human population and environmental degradation”.

John Guillebaud, a patron of the group and emeritus professor of family planning and reproductive health at University College London, said: “Deciding to stop at two, or at least have one child less, is probably the simplest, quickest and most significant thing any of us could do to leave a sustainable and habitable planet for our children and grandchildren.”

Parents of large families argue that the movement is ill-founded, however, and that we should concentrate instead on reducing the amount of resources consumed by individuals.

They also point out that large families often lead more environmentally friendly lives. Jose-phine Treloar, 48, a mother of seven from Kent, said: “People with two children often have more money and their assets are ploughed into fewer people. “ In large families there is an element of necessity that means material goods are used more efficiently.”

She said large families were a “soft target” for people who wished to pass the responsibility for reducing carbon dioxide emissions onto others.

The population of the UK is growing at its fastest rate since the 1960s, increasing by 2½% between mid 2001 and mid2006, according to the Office for National Statistics.

Fertility rates are at their highest level since 1980.

More than one in five births in Britain are to mothers born outside the UK.

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