The spectacle of someone who has it all demanding commiseration from others who don't is unappealing. Hence the nausea induced in some filmgoers by Sarah Jessica Parker's current portrayal of an over-privileged working mother valiantly juggling her multiple obligations.

Kate is married with two kids but wants to soar in the world of finance. The family and the job keep making annoying demands, all of which she pluckily tries to meet. Because she gives the appearance of more or less succeeding, people keep saying, "I don't know how she does it." We're asked to believe she does it by being a really super person. In fact, she does it by being a scumbag.

Her two-year-old son hasn't learned to talk because his mother's too busy to speak to him. When he eventually gives voice, his first words are "Bye, Mom". Her broken promises have soured her six-year-old daughter. She goes to sleep her kindly husband fancies making love. He's trying to pursue a career of his own, but when junior falls down the stairs it's Dad who has to take him to hospital, since Mom's away on business yet again.

All this is because in the nasty banking world, those who want to claw their way to the top have to work unsocial hours and travel to see clients. If they don't work hard enough, others may overtake them in the rat-race. It's so unfair.

The film will also fuel the notion that it's unwise to give women tough jobs because they're intrinsically unreliable. This is unfortunate for women like Kate's assistant, who're prepared to sacrifice the prospect of motherhood so they can give full attention to their careers. Such concerns don't occur to Kate, because of course it's all about Kate. Obviously she's not bothered about short-changing her employers: they ought to make allowances.

Why? Well, in spite of her distractions, Kate's so much better at the job than her workplace rivals. She's bound to be, what with being such a clever juggler. Eventually, her boss has the sense to realise this, and lets her take things easier than her colleagues. Hubby comes to appreciate that he's got to do more of the housework. This surely is the way things ought to be.

It's not only Kate who thinks so. Highly advantaged women often seem to assume they're entitled to total fulfilment both at work and at home as of right. If they don't get it, they've been robbed.

Yet motherhood is voluntary. Those who engage in it aren't necessarily doing the rest of us a favour. The planet has nearly seven billion occupants, and that's probably enough. People who've already been born are clamouring to come to countries like America and Britain to do whatever needs doing. Many seem to be better educated, harder working and less crippled by entitlement than our own offspring.

Still, as Kate reminds us (and her misguided assistant), having children is a great joy. Fine, but it's for women who want this benefit to ensure they can discharge the duties involved. Fulfilling all other aspirations at the same time may or may not be practicable.

Ambitious mums can try to turn their partners into house-husbands, but it would be only fair to tell them what they're in for. Instead of expecting childless colleagues to cover for them, they could admit that mumps and nativity plays will come first, and accept the consequences, however unwelcome.

If they can't work as hard as their childless colleagues to get a seat on the board, they could manage without one, instead of demanding quotas that would devalue other women who've earned their place.

It's like this, Kate. If you want to have it all, it's your job to work out how to do it. If you can't, give something up. But don't expect the rest of us to underwrite your bliss.