Till which month of pregnancy you can have sex?

Anytime,unless...: The most common exceptions are vaginal bleeding, and a "broken bag of water"(ruptured membranes). Definately, ask your OB who is more familiar with you and your pregnancy.

No limit : There is not really a limit, unless you have been advised by your OB to avoid intercourse for medical reasons that can lead to pre-term delivery. So if you have a completely healthy pregnancy, you can have intercourse until the time of delivery.