hiya whilst I have not had my baby yet and don't want to be tempting fate by saying nothing will go wrong, I'm at week 38 now and so far no sign of any probs with the baby. My hba1c was around 9 at conception - the pregnancy wasn't planned.
There is a higher chance of birth defects and miscarriage with higher hba1c's but statistically you are still more likely than not to have a healthy child. I think it is something like 20% of babies conceived to diabetics with a hba1c over ten will either miscarry, be stillborn or have a birth defect. There are various stats out there - believe me I know as I did nothing but search around on the internet when I found out I was preggers - which may not be the best thing to do.
So because obviously it is such a tragedy to lose a baby at any stage in the pregnancy the docs err on the side of caution and advise you to have a hba1c as low as you can before conceiveing. If you go ahead and conceive with a high hba1c you are running a risk that something will go wrong - obv there is always a risk for any mum but its a much higher risk. I suppose it's a bit like if you were a heavy drinker and you got pregnant - you may get away with it but then again you may not.
I guess it depends whether or not you want to minimise that risk whether to get pregnant now or wait for your hba1c to stablise. Having conceived, albeit unknowingly, with a high Hba1c I would really advise against it as I was a bag of nerves during the earliest months convinced I would miscarry and I only really began to believe I would have a baby after the 20 week anomaly scan came back clear. I am still a bit nervous to be honest that once the baby is born they will find something wrong, until he gets the final all clear I don't think I will truly relax, but I am a bit more confident now that all the scans have been ok. Also I was lucky in that once I realised I was pregnant, at two weeks after conception, I got things under control pretty quick but I know that may not be so easy for some people - if you are having problems with control now pregnancy will only make that a lot harder as the targets are so strict and later on your body will produce all sorts of hormones which work against the action of insulin.
Good luck whatever you decide to do.