If you are worried about the child being able to gain US citizenship if born in the DR you can relax. Take all the photos and keep the documents as suggested in the earlier post and then you will simply fill out the papers for declaration of a birth abroad to an American parent.
You will also have to bring in certain papers from the Domincan government, DR birth certificate and something else, check with the US consulate for details. I did this with my son 7 years ago and it was no problem even though I am American, his father Canadian and he was born in DR. (he has his own little folder of passports
)
Not trying to sound cynical but it may also help to have a DNA test done after the baby is born just to help convince the authorities.
Best of luck as you venture into parenthood.