It's rare to hear people shocked into silence, rarer still in the middle of a radio discussion programme.
It happened last week when veteran agony aunt Anna Raeburn was talking about the bad old days before the Abortion Act.
Have you, she was asked, ever met or spoken to a woman who had a back-street abortion?
"I am one," she replied.
You could have heard the proverbial pin drop. Silence.
Afterwards I understood why. Women don't talk that way about abortion, not about their own abortions. Not in my experience they don't, not even with their good friends.
Love, marriage difficulties, money problems, contraception and children are everyday topics but abortion only makes it as an issue; as a debating topic. Women discuss its rights or wrongs. They might bemoan the numbers of teenagers resorting to termination or condemn restrictions in other less-enlightened countries.
But I have yet to meet a woman who will throw into general conversation her own experience of termination. Anna Raeburn saying, "I am one" was the first time I had heard it. I felt shocked into silence too. It was that unusual to hear it spoken aloud.
So, is talking about your own abortion the last taboo?
Possibly it is and for a reason that undermines those who complain about abortions being too available. For most women a termination is anything but an easy decision.
It is embarked upon with a heavy heart. It is a time of loss and of grief. It is not a subject for light conversation ever, even with the passage of time.
How could it be anything else? Imagine a pregnant young woman who is considering an abortion. Her expectation from quite a young age has been the polar opposite of this situation. She has grown up with ideas of romantic love and of having her own happy family. Instead she probably feels alone and frightened. She might have been dumped by her boyfriend. She might be fearful of discovery by her parents. Or she might desperately want her baby but be unable to see a way of raising it alone.
She probably just wants the whole situation to go away. Then, when it does, the last thing she wants to do is dwell on it.
Sometimes women can't help going over and over what has happened but they do so in private. I have known young women who keep the anniversary of when the birth would have been. I have known one who coped psychologically until she had her first baby and then she mourned for the one she aborted.
I've also met women who never looked back. They would tell you their over-riding emotion remained one of relief.
But I never knew any of them to speak openly and easily about their experience. It belonged strictly in the private realm.
Yet I admired Anna Raeburn's blistering honesty. She went on to say she had had a second abortion during her first marriage. It was much more difficult emotionally, though the first one, the back street abortion, "nearly killed me".
It's the end of that horror we must continue to celebrate.
A long time ago I knew two women in their early twenties who were so damaged by illegal terminations that neither could have children afterwards. They were contemporaries of my older sisters, but on both occasions I somehow ended up wielding the teapot and mopping their tears.
It wasn't that long ago but it was a barbarous situation. Both had made a very human mistake for which they would pay for the rest of their lives.
How much more fortunate are young women today. In 2012 in Scotland, 12,447 of them had a safe, legal termination. I'm sure there was heartache involved but there was also physical safety. Since most of them were in their late-teens or early twenties, they will have more and better opportunities to have a baby.
Abortion in Scotland is now largely a medical procedure with 86% of terminations involving no surgery. Seven out of 10 unwanted pregnancies are terminated before nine weeks gestation and nine out of 10 before 14 weeks.
Some people may think termination is becoming too simple, too easily available. If it's merely a matter of swallowing some medicine, how will these young women learn to avoid a repeat performance?
Some don't. One-third of those who have a termination have already had one. But the good news for all concerned is that abortion rates are dropping. In Scotland they are at their lowest for four years. In England and Wales they are down 2.5% in a year.
Of those who have abortions one-fifth are teenagers. Scotland still numbers among the highest rate for countries where termination is legal. Sadder still is that rates in deprived areas are twice as high as in affluent neighbourhoods.
Iceland has seen its teen pregnancy rates drop by 25%. They have educated their young people away from unprotected sex. We need to follow suit.
The group that could take more responsibility for their actions is women in their twenties. They comprise more than half of those who have terminations. I know that life and hormones and alcohol can combine to catch people unawares but when contraception is freely available, more than six thousand slip ups a year is too emotionally and financially costly.
It isn't, however, a negative story. Scotland should be pleased with the safe and discreet way it deals with unwanted pregnancy. Looking back at the journey that has taken place during Anna Raeburn's adult life, we should celebrate. Young women no longer have to choose between an unwanted child and the danger of a back street abortion.
Those who think life was better when an untimely pregnancy carried stigma and danger only have to look across the Irish Sea for a glimpse of the unnecessary misery such a policy causes. The statistics for abortions carried out in the UK on women from Northern and Southern Ireland, where it is still illegal, tell their own tale.
In 2012 the combined number of women making the miserable journey to seek a termination was 4887. Those were the women who could afford the fare and the fees. Those were the ones not driven to risk their lives and future fertility. How many, I wonder, went to the back streets? And at what cost?
I would far prefer a world where abortion didn't exist because there was no need for it. I would prefer to see women and men use contraception well and efficiently.
In the meantime, I don't think we will hear women follow Anna Raeburn's honesty. Ours is a child-centric society and the loss of a child, even as an early pregnancy, matters.
Our silence is deafening. Yes, it is our last taboo. But I see it as a mark of respect.
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