TV Scope: Britain's Oldest Mums and Dads, UTV, Wednesday 15th March, 9pm.
In the days when the death of a child was to be expected in the average family, couples had to have many children and have them early.
Now that infant mortality is at an all-time low and longevity at an all-time high, people can have fewer children and can wait longer.
For some people, that means waiting for a very long time indeed, and even having a second go at parenthood with a new partner.
IVF treatment has helped by making it possible for some older women to give birth who could not otherwise have done so.
In Britain the number of women becoming mothers in their 40s and 50s has doubled in the past 10 years and the Irish figures are unlikely to be radically different. In general, women having children in their late 40s and early 50s - one woman had a son at 55 - know what they are doing. On the evidence of this programme they have no regrets, nor do the children. And the children seem to feel no embarrassment at finding their parents mistaken for their grandparents.
Second marriages seem to be fuelling this move towards older mums and dads. Pauline, who had the son at 55 and a daughter at 51, already had a grown-up daughter when she remarried. But she very much wanted to have children with her new husband and they went for IVF treatment. She had to lie about her age but she got the treatment and has no regrets.
Today her children are aged nine and five and the older child seems to accept that her parents may die when she and her brother are at a relatively early age.
Shirley has given birth to twins at the age of 52. She's already a granny and her partner Carl also has grown-up children from a previous relationship. But they wanted to have children with each other so off they went for the IVF treatment and now they have twins.
This trend is fascinating not only because it is new but because it turns assumptions upside down. In an era when it is assumed that people want to limit their families to one or two children, these couples want more.
And having reared children to adulthood once, they are eager to do it all again - no long mornings on the golf course for them.
And the ability to have a second "round" of children with the help of reproductive technology is also reviving a concept which seemed to have had its day: the extended family.
Babies being born when their step-sisters and step-brothers are adults will hopefully be able to turn to these adult siblings when their parents are no longer around. In other words, the extended family can become a functioning unit again, in these cases at least.
Too much should not be made of this, of course - the numbers involved are relatively small. Still, the trend is there and there seems to be no reason why the numbers should not grow.
Of course, we can always stick our noses in the air and complain that these parents are having children for their own sake and not for the sake of the children themselves. Yet children born to couples at that age and with that degree of deliberation, are being born into families that will value them, care for them and nurture them. That is more than can be said for the children of some younger parents.
Where will it all end? Who knows? Technology, combined with a desire to have children, has changed our familiar assumptions about who can have babies and when. Wait and see.
Meanwhile, good luck to the new/old parents and their offspring.
Padraig O'Morain is a journalist and counsellor accredited by the Irish Association for Counselling and Psychotherapy.