Those remarkable 4D neonatal scans are inescapable this week, as the Commons Science and Technology Committee pores over our 40-year-old abortion law. What moral weight these images carry, how powerfully they load the question: what kind of monstrous woman could terminate at eight weeks, when a foetus can kick and straighten its limbs, let alone at 24 when it can yawn, thumb-suck and “walk” within the womb. Besides, as any parent will recall, even at six weeks a baby’s heartbeat flickers on a scan, like a star signalling from a distant galaxy.

Against these arresting images, arguing for the retention of the 24-week limit feels like making the case for clubbing seal pups or drowning kittens. As if any one of the 2,600 British women who every year have an abortion after 20 weeks needs any reminder that she killed her unborn baby.

Our mental screen-savers are so overloaded with baby snaps we feel nothing for these desperate women, their often hideous circumstances and their grim decisions. A poll of British women recently found that 47 per cent were in favour of reducing the legal maximum time limit from 24 weeks. But then only a tiny number of us will, thank God, ever have need for a late abortion, while the majority become mothers. And it is so hard after you have felt a flutter inside you, at 16, 17 weeks, given birth and experienced that fiercest of loves, to understand how anyone could choose to end such a life.

Late abortion makes us queasy, and quite right too. It must be a grave matter to have a doctor insert a needle into your abdomen to kill the foetus inside you and then experience the ordeal of labour without the usual compensatory joy. A friend of mine went through it all alone, not wishing to subject her partner to such horror. But if in your routine, 20-week scan a genetic defect is discovered that will mean “she” (the sex is already cruelly apparent) will be severely disabled, is likely to die within hours of birth, what do you do? You have your other children to consider. And you wonder how you can bear to carry this baby another five months waiting for this outcome . . . OK, here maybe, the balance of current opinion might give you the benefit of the moral doubt. As it might cut slack for a woman whose health was endangered by pregnancy, or who was a victim of rape.

But what if you were a 14-year-old girl who did not realise you were pregnant for two months, then spent the next two in denial before you finally drag yourself, ashamed and terrified to a clinic? Or if you were delighted to be having a baby, but your partner is aghast, so you spend two months trying to win him around but he clears off anyway and you are unwilling to raise a baby alone. Or you are 45 years old, your nappy days long behind you, and assumed your missing periods were the onset of the menopause. I am not concocting heartrending stories for effect. These are the most likely scenarios, because whatever the critics claims, late abortion would only be used as a contraceptive method by a masochist or a mad lady.

Should these women be forced to continue with pregnancies unwillingly? I keep hearing the argument that these days there are too few babies up for adoption. As if accidentally pregnant women have a duty as willing pods for childless couples, to do their bit in our national infertility crisis. As if we’ve forgotten those haunting Fifties tales from unmarried mothers’ homes.

Or maybe they should be persuaded to keep the child, to make room, somehow, for one more. It is trial enough raising a longed-for baby; you can only pray maternal love rises to meet the challenge of raising an unwanted one. But certainly once he is born, those who would change the law won’t be around to drag his buggy up a staircase, help his mother to keep her temper with a toddler when she’s broke and lonely. “Pro-life” concern for the unborn rarely extends to the properly living.

Anything is better, then, than killing a “viable” foetus. But what does that mean exactly, when a baby born at 24 weeks cannot survive without the full battalion of medical intervention, and even then is likely to have a serious disability and not live beyond its sixth year? And as neonatal technology advances, surely there will come a point at which a 12-week foetus can be incubated in an artificial womb. Will that baby be deemed “viable” too?

Science should not rule the debate. It is, in any case, equally scientifically valid to assert that a foetus, despite being in possession of tiny fingers and toes, is unconscious in the womb, therefore not a sentient being, capable of pain, fear and full human emotion.

What needs to be addressed is how the balance of sympathy in abortion is tipping so drastically away from the woman. In part this is a consequence of a second generation that takes reproductive rights won by their grandmothers so blithely for granted. They have never heard the arguments, so why would they seek to defend them?

And they are growing up too in a culture of mawkish sentimentality, in which The Baby is now deified. Having lost our religion, all we believe in, invest in, is our own immediate genetic legacy. Today a pregnant woman – bombarded with faddish, often contradictory dietary warnings and needless alcohol prohibition – knows she is but a vessel. And since we peer ever more nosily into the womb, parenthood now begins at six weeks’ gestation: by 12 weeks we demand to know its gender, so we can “bond” better – and select the nursery wallpaper. From being a nation at best indifferent to children, we have turned fanatical.

To be a keeper of a baby, is to have guaranteed moral supremacy. I’ve witnessed mothers upbraiding disabled drivers who dared to park in “parent & child” supermarket spaces, or refusing to fold their buggies on a bus when a wheelchair user hoped to board. Adults are expected to stand for children, not the other way round.

All must pay homage to the baby. And our hearts have hardened towards those who do not. A scan of a yawning foetus cries out for our protection as no white-faced woman in an abortion clinic ever can. But it is a challenge to our compassion and our imagination to keep unlocked a door that we would never choose to open.

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