Most of the products for refinishing a floor will off-gas for quite some time and very likely you will experience a smell for many days.
VOCs might have an effect on you or the baby - so why risk it.
Enjoy the time before the birth of your baby and try to get as much sleep as possible.
Your baby will not notice or appreciate the different finish of your wood floor.
For more information:
Read Mary Cordaro's Know How article, "The Parent Trap: Avoid Mistakes in Nursery Projects By Following Three Basic Principles."