Congrats on you r baby!!!
Congrats on your Baby.
As far my conversation with my attorney, this process is pretty simple.
If your 485 is approved now (before you include your new baby), then it is very simple. When you return with the baby before the baby turns age 2 he/she will automatically get green card (no application/no fp/ nothing nbeeded).
If the baby returns before 485 being approved, say travelling with her mom who is on H4, the baby will automatically get H4. No application needed. However if you use AP,I am not sure how it will work.
In essence, if the baby is under 2 years the process is very easy and friendly..
American_desi