If there's a special relationship between the UK and the US, then talking points about reproductive health are like STDs: once the contagion has been incubated on the American side, it's sure to be transmitted to us in time. We caught the kerbside vigils, we got the disingenuous chatter about the "abortion industry" and soon we're going to suffer from something new. The very latest in the fight to make sure ladies get up the duff and stay up the duff shifts the argument away from whether women have the right to end their pregnancies should they choose to, and on to the question of whether they have a right to avoid getting pregnant in the first place.

It's not framed as a question of rights, of course. It's framed as a question of costs – because you can argue about ethics all you like, but money is its own argument and absolute. That's the tack taken by Peggy Noonan in the Wall Street Journal on Sandra Fluke's appearance at the Democratic National Convention. (Fluke, you'll remember, is the American student who was labelled a "slut" and a "prostitute" by the ever-gentlemanly Rush Limbaugh because she campaigned for contraceptives to be covered by insurers.)

"She really does think – and her party apparently thinks – that in a spending crisis with trillions in debt and many in need, in a nation in existential doubt as to its standing and purpose, in a time when parents struggle to buy the good sneakers for the kids so they're not embarrassed at school … that in that nation [author's italics] the great issue of the day, and the appropriate focus of our concern, is making other people pay for her birth-control pills," writes Noonan, as if a course of oral contraceptives were a delicious sugar-coated snack and Fluke was selfishly dipping into the public pocket for the cost of her candy. (Personally, I'd say that a nation in "existential doubt" really doesn't need a lot of unplanned babies to worry about as well.)

Noonan's keen on price tags, so let's get the sticker gun out and apply some more numbers to contraception and childbirth. Having a baby is expensive, whether you can stretch to the superior make of trainers or not. Even if you kept your kids in plimsolls (£9 a pair when I was doing the annual ritual of levering out a kidney and splatting it on the counter of the school uniform shop last week), you'd still have to stump up for the rest of the food, the clothes, the housing that children are inconvenient enough to need.

But that's all still a personal cost to the parents, so by Noonan's logic contraception could still be lumped back onto women as a long-term saving. There's more, though: having a baby blows a massive hole in women's earnings and the less money you have to start with, the worse the motherhood penalty is. That's a loss to individuals; it's also a loss to the economy as a whole. Helping women to time their pregnancies helps them to stay employed after they've become mothers. I see that as allowing women to maintain their independence and dignity, but if it's more palatable to Noonan, she could always imagine them as "continuously productive economic units" rather than "people".

And of course, there are the healthcare costs of being pregnant and delivering a baby – which American insurers are unsurprisingly keen to wriggle out of; just moving women from the pill to more-reliable long-acting reversible contraceptives like the implant or coil could save the NHS in England about £100m per year. That's loads of money saved simply by moving from a good method to a really good one. Now imagine how much money the NHS saves by offering some contraception rather than none at all and you'll see a figure astronomically greater.

The ability to control fertility is a usually seen as a victory for women, but that's too narrow: the revolution in fertility is a victory for everyone, male or female, parents or childfree. Personally I'm amazed that men haven't cottoned on to the joy of sex without the risk of a surprise baby and started to clamour for their own version of the implant. (Seriously, guys, it's amazing; and you get to pretend you're bionic when you feel the magic plastic stick just below the skin of your arm.) If someone tells you contraception is too expensive, the first thing they're telling you is that they're not very good at maths; the second, that they think we can afford to go back to a time when women were just mothers-in-waiting rather than people in their own right.