We have navigated the hospital's nonsensical slalom of precipitous stairwells and snaking corridors that have clearly been designed as a cruel joke aimed at people on crutches. We are displaying the precise, to-the-millisecond punctuality of those who are very nervous about the thing they are trying to be punctual for. We are slightly out of breath.
The two receptionists sitting beneath the big 'Obstetrics' sign do a truly magnificent job of not noticing us. 'Excuse me... um... we have an appointment for a scan at 11.30.' 'Just take a seat'. For us, this appointment is a crucial milestone in our lives; for them, it's an average Tuesday morning spent shepherding jittery, worried-faced folk through one of the most routine procedures the NHS does.
All morning a carnival of outlandish what ifs has been parading through my mind: What if there's no head? What if it's a goat? Dear God, what if it's twins? By the time our scan operator, a brusque but likable lady called Janine, ushers us in to a small room that looks alarmingly like a dentist's surgery, I just want it over with.
Once in, there's a lack of ceremony that takes us both by surprise. With the air of a car mechanic's 'Pop the boot, love, let's have a look', Janine commands a hoisting of T-shirt, slops on cold goo and a thing that looks like a supermarket barcode reader and twists the screen towards us. We get our first, fuzzy glimpse of the person (it's not twins) who's been treating my wife's internal organs like a bouncy castle these past few weeks.
Until today our pregnancy hasn't felt real. But seeing it on camera, it now feels even less real. A creature which isn't quite recognisable as human is waving at us - actually waving - and I am stunned. 'Your husband doesn't talk much, does he?' says Janine. Before I can protest, she points out the foetal heartbeat, a tiny flitting butterfly of light behind what looks like an elbow.
I've seen ultrasound pictures before, so had some idea of what to expect. But I had not been prepared for all this movement: stretching, overhead kicks, tummy tucks - it's like it's in training for the decathlon in there. Janine, though, has decided our squirmy friend isn't putting on enough of a show, and gives my wife's belly a vigorous jab with the scanner, yelling, 'Wake up, lazy!'
The response is instant. From its position, reclined and in profile, the creature rolls on its side, and stares face on into the camera. All I can think of is that scene near the start of Ghostbusters in which Bill Murray sees the ghost of a beautiful woman reading books in a library - but when she turns towards him, her features mutate into a screaming skull of death. Prospective parents be warned: at 12 weeks you'll see eye-sockets but no eyes. Another film pops into my mind - it's Scanners, the horror classic where an unborn child reads the mind of its father and causes his nose to bleed. I stop thinking about films, and instead start thinking, 'Nice baby... nice baby...'
As Janine takes measurements (spine-to-crown, head-width, leg-length) and tells us each one looks normal, we are transfixed by the being on screen. I realise this is how we all started: bobbing and rolling about in pleasantly warm soup. It looks nice in there. A cosy, private world of your own, where life is nothing but a dream getting louder. I feel a twinge of guilt about nosing around it uninvited, as if we've been watching secret CCTV footage of nuns at prayer. But it's a wonderful sight, and all too soon the nurse is winding things up, gently kicking us out to make way for the next pair of gawping breeding machines.
Sweet dreams, then, little person. See you in nine weeks...