my contacts lense prescriptions are 8 and 10... I always have my glasses w/in reach, if I am not wearing my contacts, it is a necessity.
I didn't have trouble during labor... just brought saline and a case with me, just in case. In most cases you'll have plenty of time in labor before you push and while you push, so if you notice your eyes getting dried out you could take them out for a while and still have time to put them back in. Hospitals are really drying, so I did notice that.... but since you are at home for birth, you won't notice that... (hey yet another home birth plus!!)
I just think you will want to take them out for a bit-- at least to clean them, rewet them, especially if you end up up during the night, etc. That helped me- so perhaps have someone remind you to do that at some point. My labor with #2 was (wonderfully) intense and quick, but I would have had plenty of opportunities to take care of my contacts had I needed to-- just would have needed a prompt to DO it, as it was NOT on my mind at all.
As for post baby--- I was a little crazy with ds #1-- but he was also intense. The BIGGEST visual help to me was having a nightlight and flashlight... so I could get around w/o having to turn on the big lights. I still rely on a nightlight for my nightime parenting needs- especially w/ dd now 8 weeks.... back to why I was crazy...
With my son, I basically put my contacts on every time he woke up in the night for the first month, at least. This is a because I was #1 not used to my glasses and #2 the prescription was slightly off.... and #3 some first time mom insecurities. I really don't remember why but the few times I tried to do things with just glasses were very uncomfortable to me, so that was my solution.
This time, I have not needed to do that at all- I do just rely on my glasses, but they are FAR better than other glasses-- ( I have very little side of the side distortion/movement that drove me crazyy).
And if stairs are involved (especially holding baby) I am triple careful... and would prefer my contacts-- so I do know where you are coming from.
Oh, yeah.. this time I remembered to bring a new pair of contacts with me. So after the birth and my post-birth shower, I put on a fresh new pair of contacts (-; It just felt nice and right!
Hope that helps....