I think a lot of people have these kind of fears whilst PG and it's understandable because you're branching out into the unknown and of course you want to ensure that your baby arrives safe and sound.

Scans can be inaccurate when it comes to estimating weight etc - they are only an estimate. That said, they can of course be a wonderful diagnostic tool and provide fantastic piece of mind. The best thing to do is to wait and see how your PG develops - I'm sure that as you go along you'll read and research a lot about the kind of birth that you want, and it's best to discuss your concerns with your care provider so that they are well informed about your fears for getting your baby out - they can then discuss this with you in a way that is relevant to your situation. There is a great article on the main site Fears in Labour - Top 12 Fears which you might like to take a look at.