I am assuming she is in the US of A and you are abroad at the moment. I also assume you need a US visa to enter the USA.
Formally, you need an F2A immigration visa, so that you can join your spouse and family to live in the US. This visa currently has at least 2 year waiting period. This sucks.
The other option would be a B-1/2 (visitor, family visit) visa which assumes non-immigrant intentions. According to the US law, every applicant for a visa is presumed immigrant, and it is your duty to overcome this presumption in order to get a non-immigrant visa. Given the circumstances: the submission of I-130 + presence of your spouse and future kid - it will be very hard to overcome.
Having said that, is there something you can do to convince the consular officer that you intend to return back after a brief visit to witness the birth of your child? Maybe an unfinished work contract, business obligations, caring for an elderly relative? It may be worth a try.
You might want to get a good lawyer on your side, the one who will immediately follow up with the US consulate if need be. Also, the same lawyer may help to follow up through your spouse's local congressman and/or senator.
PS. I would also like to notice that the fact you started arranging your visit just mere 2 months before the delivery does not speak in your favor. You need to do some very convincing explaining.