My pregnancy didn't become externally apparent until quite far along, but the “Baby on board!” Badge was obviously quite clear as I stood on the Tube going home late after work one night.

I know that because the man sitting in the clearly-labelled “priority” for preggers and otherwise hard of movement seat tugged at the elbow of my jacket as I held the handrail, willing him telepathically to GTFO.

“Where's your baby?” he said, nodding his head towards me. It took me a moment both to work through what he was asking, and also that a total stranger had so brazenly touched me.

“What?”

“Where's your baby? Your badge. It says you have a baby.” My thoughts at this point included: is this guy completely stupid? and if you're going to be enough of a dickwad not to offer the seat, at least pretend not to have clocked the pregnant woman, surely?

“It means I'm pregnant.”

“Oh. Good joke!”

A moment of stunned silence and narrowed eyes. “No, it's not a joke. It's so people like you who are sitting in the priority seats have the opportunity to offer them to people who need them more. Like pregnant women.”

“Oh. Ok,” he said, continuing to sit exactly where he was – just like everyone else in earshot, most of whom were staring at their shoes and pretending not to have heard the exchange.

It was one of the slightly more memorable preggo-related encounters I've had on the tube, but not one of the atypical. There was one woman who physically pushed me out of her way so she could run to a vacant seat; another guy who saw my badge, and then looked pointedly at my belly before deciding I was clearly just making it up and staying where he was.

And while I'm aware, as The Writer loves to say, that the plural of anecdote isn't data, I've been scratching down a quick tally of my experiences – and seeing the numbers in black and white has been deeply disappointing, to quite a surprising degree.

Taking into account all the tube journeys I've made since being pregnant (around six months), during which I've been wearing a “Baby on board” badge, and have been standing up because there are no seats available (and I've also not felt so desperate that I've flat-out asked someone to move, which I quite merrily do), I reckon I'm offered any seat (not just the priority ones) some 18% of the time, with two thirds of those offers being made by women, and usually younger women. Where the offer's been made by man, I don't think it's ever been made by a man over 40.

Yup. That's fewer than one in five people.

Early on, with a flat belly but an inclination to sleep against anything you're not about to be sick on; or a little later, when your stomach muscles have come apart leaving you with little core strength, no balance and a constant fear of falling over on a jerky tube; or when your unborn darling is kicking, not gently and endearingly, but thumpingly and painfully in the cervix, you don't want to have to ask people to move. You don't want to have the awkward conversation as they look at you with a high level of scepticism. And you certainly don't want to be forced into shaming someone as an unthinking arse in front of their fellow commuters.

For a few moments, you just want to sit down, to be able not to think about how shocking you feel, and ideally next to a door so you don't have to make a Sherpa-like climb through a horde to get away again.

So next time you happen to be in a priority seat on the tube, don't stick your headphones in your eyes and your nose in the Metro, conveniently unaware of the humans around you who will appreciate a small act of kindness more than you could realise. Just don't be a dick.