Listening to CNN’s live coverage of John McCain and Barack Obama from the Saddleback Civil Forum early on Sunday morning, I fell to wondering how many abortions the average woman reader of the Telegraph has had.

More than you might think is the answer. More than women readers themselves might think.

That’s if John McCain was right in his reply to Pastor Rick Warren before a 5,000-strong audience in the Saddleback mega-church just a few miles south of Disneyland in southern California.

In separate interviews, Warren pitched the same set of questions to each candidate. One was: “At what point does a baby get human rights?”

Obama, typically, adopted a furrow-browed expression of philosophical concern, and waffled: “Whether you are looking at it from a theological perspective or a scientific perspective, answering that question with specificity, you know, is above my pay grade.'”

McCain, in contrast, interrupted before the question was out: “At the moment of conception!” Cue wild applause.

I left the debate at that point and logged on to Bloomberg.com to re-read a suddenly-more-interesting article posted the previous week by news columnist Ann Woolner.

“It's impossible for me to know how many abortions I've had,” began Woolner. “If asked last week, I would have confidently declared, none. Now, I don't know. It depends on what the meaning of the word ‘abortion’ is.”

She went on to report that the McCain line on the beginning of life has been anticipated by Bush’s Department of Health and Human Services: the department has just drafted a rule which a McCain administration would presumably try to insert into federal law. This decrees that an abortion has taken place when a contraceptive prevents a fertilised egg from embedding itself in the uterine wall — one of the ways many birth-control pills work. If that's abortion, millions of women who didn't know they were pregnant, and who, medically, were not pregnant, have had multiple abortions.

The rule, observed Ms Woolner, “would give a ‘human being in utero' status to the itty bitty zygote”.

Smaller by far than a single grain of salt, the zygote is the cluster of cells formed when sperm penetrates an egg.

It travels toward the uterus and either keeps going and leaves the woman's body, or attaches itself to her uterine wall some five to 10 days after fertilisation.

The logic of McCain’s position is that if the departure of the cluster of cells from the body happens naturally, that’s the death by natural causes of a human being, with the same moral significance as the death of a mother, a father, a child, a friend. If the departure is brought about by a pill, that's murder, the moral equivalent of a member of your family being knifed to death.

But according to standard medical definitions, Ms Wolmer pointed out, a woman isn't pregnant until the zygote lodges. Pregnancy tests register negative if taken before that.

It might be thought that if the aim of opponents of choice is to keep the incidence of abortion down, they’d be pressing for more readily available birth control. But no. Here, as in the US, those who share McCain’s view campaign to ensure that rape victims or women pregnant as a result of incest are refused emergency contraception. This is the practice at most hospitals in the North, where, effectively, the ethical framework is set by adherents of Christian fundamentalist teaching.

Woolner quotes Douglas Kirkpatrick, president of the American College of Obstetricians and Gynecologists: “This practice is an affront to health professionals and American women.”

The American Medical Association has written a letter of complaint to US Health Secretary Michael Leavitt, as have 28 senators, calling the practice “utterly irresponsible”.

Anti-choice campaigners in the US, as here, appear to believe that repetition of the phrase “Abortion is murder” counts as an argument. But it doesn’t. It is statement of belief. And it’s being imposed on women who don’t accept the belief.

Nobody at all suggests that acceptance of abortion as a legitimate choice should be imposed on anyone who doesn’t believe in choice.

But the self-styled “pro-lifers” won’t accept that those who do believe in the right to choose have the same right as themselves to live by the precepts which accord with their own conscience.

What opponents of choice like McCain and those who run most of our hospitals are saying is that a woman who is distraught to discover that she is pregnant, no matter how the pregnancy came about, no matter what the implications for her own well-being, no matter what her beliefs or what her own conscience tells her is right, must be forced, by law or lack of facilities, to carry the pregnancy to full term. They have a fundamental cheek.