That depends on too many variables to answer here. Generally, if a woman is healthy and has a healthy pregnancy, intercourse may be safe right up to delivery time. If she has complications, intercourse may not be safe.
Depending on your anatomy and hers, bumping the cervix would not be a good idea. Using any type of chemicals (including many lubes) can be risky. A condom should probably be worn (to minimize the risk of introducing microbes).
Generally speaking, if intercourse is uncomfortable for her, it's not ok. If it is comfortable for her, it's usually ok.