Hi,
I also have a similar problem.
Currently I am staying in 1 bedroom appt in PA.
I am in a 1 yr lease that will get over in Nov.

We will be having a baby soon.

My question is, in this case, since we will be 3 people in the 1 Bedroom, can we continue to say till we complete the lease or is it necessary to move out.

I cannot go in for a new lease as I will be relocating in Dec.

I have heard that I can stay in 1 bedroom till the child is 18 months.
Is that true.. Please advice.

Again remember normally there is no real "law" there may be some zoning codes and there will be rules of the apartment complex. And of course if you are being investigated by Child Protection Services you have their rules to worry about.

You can have 5 people in a one bedroom in some places, landlord does not care as long as he is getting his rent check. I have seen 8 or 9 people * counting kids, in some of the areas where I used to have my rentals
** not in my specific rental but in those in that neighborhood.
I have 5 or 6 in the two bedroom next to where I live right now.

First its not a good idea to piggyback your question on someone else's. This can lead to confusion. You should start a new thread. So I've moved your question to its own thread.

Unless you are in public housing your landlord isn't going to turn you out because you have a baby. Even then, I doubt yoyu will have any issues here. I would just not even be worried about it.