Seeing all those limbs present and correct and flailing about manically has to be one of the biggest joys of being a prospective parent.
There's nothing quite like the wonder of knowing that the little creature you're looking at is only six centimetres long, yet somehow manages to have a head complete with nose, two arms with hands and fingers, two legs with accompanying toes, all its vital organs and even, it seems, the ability to look like it's waving as if to say: "Hi folks, I'll be with you soon."
The way it was jumping around on screen I wouldn't have been that surprised if it has started break-dancing.
For some parents this must also be a heartbreaking time when they realise something is wrong. But for many parents it's when it seems as if things are really happening and all your partner's morning sickness and tiredness has been worthwhile.
To be honest, in my case, there was also a sigh of relief as I looked at the screen and thought: "Thank goodness it's definitely not twins!"
Don't get me wrong, I'm sure twins bring their parents lots of pleasure. But I remember, from the antenatal classes last time around, seeing a picture of two babies breastfeeding at a mother's bosom at the same time.
The person taking the class asked me how it made me feel. I was honest. I said it seemed like a window into a nightmare.
The woman in the picture looked blissfully happy of course. But I couldn't imagine my wife with that expression on her face in the same scenario. And to me the thought of coping with double trouble, with two sets of everything, seemed simply unimaginable when the prospect of just one felt so terrifying.
After the scan you get a few snaps to take away. To everyone else these look exactly the same as all other baby scans. But to parents they are like gold dust. I bet some people even have T-shirts made up.
In fact, I've just checked on the internet, and yes, they do.
While on the web I decided to see what advice was around on the net for dads to be.
Here, paraphrased, is a sample of some of what I found:
Forget sex as she probably won't be up for it – try other ways to be intimate, like rubbing her feet instead.
Mmm, I don't think most man would think it much substitute.
Be understanding and patient and try not to run away to the pub too often. Think about giving up alcohol for a bit too.
There is, I have decided, no way I'm getting through her pregnancy without booze.
Tell her she looks great in those maternity clothes.
There's no chance my wife would fall for this as she doesn't believe me when she's not pregnant.
Don't rush your wife to hospital at the first sign that a baby is on the way.
Oh come on, most dads would book them in two weeks in advance if they could. I've read enough stories about blokes delivering babies in lay-bys not to fall for that one.
In other news - we've now told our first born. This has been useful in some ways. I managed to get him not to eat the whole of an enormous piece of cake the other day by saying mum needed to eat it for the baby.
On the other hand he also already seems to see it as a rival, aiming to squash my wife's stomach at any opportunity.
Meanwhile mum's habits have become worryingly like my bad ones. It used to be me hiding treats around the place for secret late night feasts, now she's found and eaten them before I've had the chance. Shameful.
You can catch up on Dad's Pregnancy Diary instalments here.