This summer I've been in that black hole that every working mother falls into at some point: when the childcare fails. The person who was looking after my children decided to leave, and I have been struggling to find a replacement. Some women cope by calling in sick; others hunch over the mobile between meetings, organising extended “playdates” with sympathetic friends and explaining to ageing relatives that Teddy must go in the cold wash, however gooey he is. When you're in the black hole, the gravitational pull of home can become overwhelming.

I'm lucky. So far I have been able to afford to pay for someone to come to my home to care for my boys, and every childminder I've employed has been great. But it's getting harder. The credit crunch is spooking many professional mothers back to work. I have spoken to two nanny agencies whose books are suddenly full of mothers who had not expected to return so fast, but fear the mounting bills. They would have to make good money though to have much left over from what the agencies say is the going rate for a London nanny: £20,000 to £30,000 a year.

The costs of full-time nursery care are also up, by a third in four years. So for many mothers the financial benefits of working must be getting more and more marginal. But that does not stop the frenzy. I have made two job offers that were trumped by other parents within hours. Gazumping is back: just not in the housing market.

At any one time there must be hordes of us middle-class mothers online, sifting e-mails from Romanian au pairs and Jamaican childminders and newly arrived South Africans who sound terrific on the phone until they mention that they can't drive. It's uplifting because of the numbers of would-be carers from all over the world who have reserves of patience and fortitude that I blatantly lack.

It's also dispiriting to get so many e-mails from people who say quite openly that they would like to work with children simply because they are bored with their job in a shop or café. A nice graphic designer I interviewed admitted that childcare just paid better than her true vocation. There are a host of would-be childcarers who have, it seems, almost no interest in children.

The au pair/nanny/childminder market is surprising in other ways. One is the speed with which we choose the person to whom we will delegate our precious little charges. Companies interview candidates as many as six or seven times when filling an important position; parents make their minds up after two meetings at most. We relinquish our children's days to strangers easily. Long days they are too: what is a gossipy lunch hour in the canteen to me could be an infinity to my three-year-old if he was unhappy.

An Ofsted report yesterday gave warning that more than half of the childminders and nurseries in some London boroughs are “inadequate”. Which is why so many of us prefer to rely on relatives, or trade up to someone who can form the “one-to-one attachment” that the experts say is so important in the early years.

Yet I wonder if we are kidding ourselves there too. What has really struck me in the past few weeks is how few people applying for childcare jobs have ever stayed for more than a year in any previous position. This is partly because of visa restrictions, and youthful aspirations to see the world. One applicant told me yesterday that she had just come out of a “very long-term job” and couldn't commit to another: it turned out the job had lasted ten months.

But there is also shameless exploitation. I have met one girl who gets calls from her boss at 10 o'clock at night to complain about her ironing. Another is looking after three children almost every weekend because the parents, both professionals, are continually away. Both girls are Eastern Europeans, very sensible but lonely and worn out at 23. There are far too many young women who are desperate to find new positions because the parents never come home on time and go away so often without the children. Some of these girls exhibit more concern about their charges than the parents seem to.

The result is a merry-go-round in which children are bundled on to form an attachment with Eva, only to find her replaced by Kate and then by Norah. The girls are probably much better than the parents deserve. But to the children, they are strangers. The notion that a child might be looked after by a parent and by one other familiar person in their pre-school years, an assumption that I vaguely made when I went back to work after having my first child six years ago, now looks utterly quaint.

Children are famously resilient. But the merry-go-round is so ubiquitous that it is easy to overlook the possible effects. You can't pay lip service to young children's need for a stable scene if you're constantly changing the characters.

This weekend I overheard a woman of about my age in the gym. A friend was asking her about her holiday. “It was great,” she said. “But now that our oldest can speak, she can say ‘please don't go'. That was a bit of a drag, to be honest.” What has happened to the notion that we are responsible for our own children? Some people seem to have families without the slightest intention of nurturing them. We recently visited an animal welfare centre that will not let you adopt a dog if you work full-time. The analogy with children was horribly obvious. I breathed a sigh of relief that I am part-time.

What is extraordinary is how, in only one generation, we have come to see looking after our children as a job for other people. I am no better. I don't quite know how I got here. But I'm still hoping to find that great person who has more patience than me and who might just stick it out for several years, warding off the time when the next black hole sucks me in.

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