The old fashioned way wrote:
We figured we weren't aborting them if there was something wrong, so there was no point in blasting them with ultrasound.
Total respect and understand this concept, but while considering this idea I came to the conclusion that it is better (for me) to know if there are going to be any abnormalities in order to prepare for them rather than go into them blind. There was never a thought of abortion or adoption or anything else like that - just being prepared.
As for advice for the OP - just finishing up my first and this feeling does not go away. There is always something else to learn and understand along the way, so just be flexible along the way. To echo the two most important things that I read from earlier posters: 1) If you have these feelings it is a great sign you will be a great dad. Simply put, it shows you care. 2) It is okay for you to have these feelings and ask questions about these worries or nerves, but your wife is going to be on so many hormones and emotions that you need to be the cognizant one. Ask the proper questions, understand the full situation before jumping to conclusions, and be as calm under the stress as possible. One of the more dangerous things to your unborn child is the mother's stress so you need to mitigate it, not add to it.
Congrats on the addition and good luck! Judging by the current responses, you are not alone on this board, so if anything else comes up this seems like an alright place to come and ask questions - never thought I'd say that about LRC...