The revelation by the American Society for Reproductive Medicine that women in their fifties can cope with the stresses of parenthood as well - or as badly - as anyone else has again raised the prospect that the experience of women such as Dr Patricia Rashbrook, who this year became the oldest mother in Britain at the age of 62, will become increasingly common. That seems unlikely for now. Treatments are expensive, unreliable and imperfect: both Dr Rashbrook and Adriana Iliescu, said at age 66 to be the world’s oldest woman to give birth, needed donated eggs.

Still, with time, who knows? And the effects may be more far-reaching than we imagine, as they were when women last enjoyed a sharp improvement in control over their fertility. Harvard economists Claudia Goldin and Lawrence Katz have traced the effects of the introduction of the contraceptive pill to the US. They say that it sparked a revolution in education and women’s participation in high-powered careers.

When the pill became more widely available to young, unmarried women there around 1970, college parties probably became a bit more fun. But the effect on undergraduates was more than a sexual liberation; women knew that without having to abstain from sex they had control over when - and if - they started a family. That made it possible to plan ahead for a career with a long pre-qualification period, such as law, medicine or dentistry. A woman knew she could qualify and establish her career, becoming a doctor without also becoming a nun.

There were indirect, reinforcing effects too. Women also felt more able to postpone marriage - why hurry? And as more intelligent females delayed getting hitched, that meant that more intelligent men would be floating around, unattached. The dating scene became a more interesting place to dip in and out of for a decade or so, and the risk of being trapped with a small choice of husbands (”sorry, only the economists are left...”) fell. Potential mentors and employers also had more confidence that women would not give up their careers because of an accidental pregnancy. Such effects helped to increase the number of women starting medical school during the 1970s from less than 10 per cent to a third; in law, business and dentistry the climbs were even more dramatic.

But what the pill did not do was reliably allow women to stop the biological clock. So ambitious young women who also wanted families still faced a difficult choice over timing. Doctors warn that later pregnancies are more risky, but the economist Amalia Miller has proved that earlier pregnancies are risky too - to women’s careers. Professor Miller showed that women who delay having children for only one year earn 10 per cent more over the course of their lives.

Cause and effect seem unclear, because a woman might delay pregnancy to earn more money for some third reason, such as ambitiousness. But Miller solves that problem by looking at women who, because of miscarriages or accidental pregnancies, do not have children when they would have chosen.

Women may have already overtaken men at US schools and universities, but perhaps they will not do so in the boardroom until they can reliably delay pregnancy into their fifties and sixties. Then employers might start to dismiss as remote the risk that a valued employee will take time off to have a family. Indeed, having one might become something you do once you’ve made it to the top and retired.

Perhaps this is nothing more than science fiction, but if my daughters become part of this future revolution, they can forget about leaving their kids with grandpa.