Exciting news from the American political scene: birtherism is back! No, not birtherism as in the nonsensical conspiracy theory about Barack Obama actually being born in Kenya, once so popular among political geniuses including Donald Trump. Please – that kind of birtherism is so 2008 (and 2009. And 2010. And 2011. And 2012 …) I'm talking about the all new, all shiny 2014 birtherism: Clinton birtherism!

Chelsea Clinton, as you may have heard, is expecting a baby with her husband, Marc Mezvinsky. What's that you say? "Awwwww"? "Bless the happy couple"? Well, I'm afraid you're just not trying hard enough because, over in the US, the noise that greeted this happy announcement was the sound of a million axes being ground.

First came the inevitable weirdy-weirdos who are so incapable of thinking about anything other than women's reproductive organs for more than two seconds that they managed to turn Clinton's birth announcement into a debate about abortion: "It's no secret that the Clintons support abortion," intoned an editorial in the Christian Post sorrowfully. "But when it's their own grandchild, it appears the Clintons see things differently. No talk of a non-person foetus, only of a child." Yes, the sheer hypocrisy! Imagine, wanting to give women access to abortion, but not actually wanting to abort every single pregnancy? Seriously, my brain is bursting trying to compute this nonsensical contradiction.

Next came the new birthers who saw not the happy miracle of life but mere campaigning. Newsmax's Steve Malzberg kicked off proceedings nicely with the statement: "When I say [the pregnancy is] staged I have to believe she's pregnant, if she says she's pregnant." That's generous of you, Steve! Pray, continue: "But what great timing! God answered Hillary Clinton's prayers and she's going to have the prop of being a new grandma while she runs for president."

Yes, the prop of one's 34-year-old married daughter having a baby! Whoever heard of such a crazy scenario? Those scheming Clintons really will do anything to get ahead. Bill may well, in his day, have played a role in various women's sex lives, but who knew he could command his own daughter to conceive? Others echoed Malzberg's sentiment, with much talk of Hillary Clinton deliberately "softening her image" and "adding compassion" to her persona via the medium of her unborn grandchild. People who actually seem to believe this span the political spectrum, ranging from conservative writer Michael Goldfarb, who tweeted: "Just in time for HRC [Hillary Rodham Clinton] to have a baby on stage with her when she announces she's running, right?", to New York Times columnist Andrew Ross Sorkin, who said on MSNBC: "Can we talk about the human drama that is Grandma Clinton? I'm not suggesting that anyone's having a baby for election purposes, but …" Gotta love that "but"! And what is this "human drama … Grandma Clinton"? Is it a new HBO series? Because I've been looking for a new one since Breaking Bad finished.

But by far the biggest debate is this: can Hillary Clinton run for president AND be a grandmother? Oh, women – always wanting to have it all, aren't they? Well-known US TV journalists have expressed disbelief that the two roles could possibly be combined: "President or grandmother?" asked Charlie Rose, who somehow manages to combine being a prominent interviewer while also being an occasional ass. On NBC, David Gregory fretted over whether Clinton's impending grandmotherhood will "factor into" her decision to run. "I don't know, David. Did the birth of your three children make you worse at your job?" snapped Erin Gloria Ryan at Jezebel.com. Sadly, Gregory has yet to respond. "Perhaps it's sexist even to ask the question," began an editorial in the Christian Science Monitor, promisingly. "If we had to guess, we'd say that Hillary Clinton will be a tad less interested in running for president now that she's about to be a grandmother." Yes, you know what those old ladies are like: one hint of a grandchild and they're too busy knitting booties to bother worrying about world affairs.

Who knew being a grandmother was such an all-encompassing job; one that prevented a woman from doing anything else? As it happens, the Sunday Times reminded readers of this fact when, in a front page headline, it described the distinguished Margaret Archer, head of the Pontifical Academy of Social Sciences, simply as "Grandmother, 71". Whether stories about, say, David Attenborough will now be headlined in the Times "Grandfather, 88" have not yet been confirmed. But then, women must always be defined by their fertility, or even their children's fertility, whereas men are, of course, defined by their jobs.

Just as old-school birtherism – "Barack Obama was actually born in Kenya!" – was really just code for "Holy hell, we can't possibly have a black man as president!", so the current birtherism – "Hillary can't possibly be a grandmother and run for office!" – is really just code for "Holy hell, we can't possibly have a woman as president, and an OLD one to boot!" Mitt Romney, to take one random and deeply obvious example, is the proud grandfather of 23 grandchildren, two of whom were born while he was on the campaign trail, and not once was this raised as a potential disadvantage. Many presidents have been grandfathers in office, although it's actually quite hard to figure out how many because, guess what? No one ever gave a good God damn, so no one kept track. Funnily enough, Jeb Bush, who may well be Clinton's opponent in 2016, is also a grandfather, but that has yet to be raised as an issue against him. Then again, he does come with other baggage. So Clinton can console herself with this thought: if the most idiots can knock her for is being a grandmother, she probably has that election sewn up.