Rowan Pelling: Trust me, Kirstie, you'll be back

That career business starts to look strangely appealing again once your baby becomes a toddler

I don't deny it's vile to yearn for Schadenfreude at Kirstie Allsopp's expense, rather like plotting an assault on a liquid-eyed Jersey heifer as it nuzzles you trustingly. The Location, Location, Location presenter is just too scrumptious for the usual brickbats that accompany fame. She makes me think of crumpets, hockey and The Railway Children. In keeping with that throwback persona, she's just announced her intention to become a full-time mum (her son, Bay, was born in July) when her contract with Channel 4 ends in 2008: "I think of myself as Kirstie Allsopp, Bay's mother, now, not Kirstie Allsopp, TV presenter. I know it's not a trendy thing to say but I want to stay at home and look after him."

Bless her cotton socks, down to the touching use of "trendy", the sort of term now only used by vicars and Brown Owls to describe McFly. Where Kirstie is wrong, however, is in believing she's not hugely "on trend", as we fashionistas put it, in asserting her desire to be a stay-at-home mother.

Hardly a week goes by without the Daily Mail exultantly reporting a high-flying female executive abandoning the boardroom for the nursery. It's increasingly common for celeb first-time mums (with the usual exception, thankfully, of Kate Moss) to announce that their gorgeous new bundle comes before their career and they will henceforth be forsaking crazed ambition for the domestic hearth.

But I don't blame Allsopp for being a teensy bit precipitous. Baby Bay is three months old and sounds as scrummy as his super-yummy mummy: "All my friends kept saying I would feel a loss of identity and how exhausting newborns are, but he is just incredible because he sleeps all night and he is so much fun." Bet her chums are glad to know how wrong they were!

When my son was three months old, he too was an obliging poppet who slept at night and gurgled happily by day, and I hadn't yet learnt not to mention this fact to women whose babies sobbed uncontrollably and often inexplicably. I even had the gall to write a column for this paper declaring, with my many eons of parenting experience, that babies were far easier to deal with than work. My excuse is that I now know three months marks a particular point of love-fuddled stupidity in the life of a new mum with a good-as-gold baby. You congratulate yourself on your relaxed parenting style, without realising how much is nature rather than nurture. You feel like the book of Baby Revelations has been opened to you and you must share the Good News.

This head-rush of slavish infatuation is not dissimilar to falling madly in love with a handsome, upright man and thoughtfully sharing his many selfless acts of kindness with your female friends. How grateful they are to know that he marked your first five weeks together with earrings and a vast bunch of roses when their own boyfriends fail to remember their birthdays. The truth is the person with a rougher ride in love or parenthood is rarely less enamoured or less enlightened - although they are frequently less boring and more tactful.

No new mother can envisage either the evolution of her child or of herself as a parent. The novelty of new parenthood after years of relentless, career-driven grind has a euphoria all its own. And happy, gurgly, tiny babies are uniquely mobile and socially acceptable. Friends, restaurants, parties and shops all welcome you. But try going with a super-mobile, attention-hungry toddler (that's any toddler), who throws a wobbly after five minutes in an adult environment.

Two years down the line, when you've truly sampled the monotony of playgroups, potty training and an infant's routine, when enough people have asked you, "What are you up to?", and the answer is always, "Reading Thomas the Tank Engine", that's when you know if you're made of the resilient stuff required by full-time parenting. It's not only loss of status (although that yields unexpected pain); there's no loneliness like standing in a group of ex- colleagues at a party talking shop and realising you have nothing to contribute.

And it's one of the many paradoxes of child-rearing that as your offspring become more interesting, in terms of interaction, they also become more tedious: you're fascinated and gratified by their developing grasp of language, yet bored to tears by hourly conversations that go: "I like diggers, mummy. You like diggers?" "Yes, darling, they're OK as far as they go." "I like yellow digger, mummy. You like to play digger?" "Well, actually sweetheart, I'd rather poke my eye out with a crochet hook."

The more besotted I am by my son, the more grateful I am to my brilliant childminder, Sue, who rescues me three days a week from simultaneous surges of irritation and impatience. As my household's major wage slave I didn't have the choice to become a full-time mother, which I once fiercely resented. Now I know the working world contains its own strange paradoxical qualities - not only scourge but also salvation.

Allsopp says: "Since I've had Bay everything has changed." True. But it could all change again. Teething will soon be upon her and sleepless nights may yet be her lot. I would be surprised if the charming Ms Allsopp proved a permanent exile from our TV screens. Not in a life with so many pleasant choices.