A while ago, I was poking around the Catholic section of Reddit, since I was curious about how the topic of birth control might be handled within it. In a comment to one post, someone stated that his girlfriend was diabetic and could only have very carefully planned pregnancies, as pregnancy could jeopardize her life. In response, another commentor argued that the "correct" Catholic response would still prohibit use of "artificial" birth control methods.
These questions (1, 2) suggests that there's some general precedent as to what happens if the woman does get pregnant, but that's not my concern here. I'm more interested in this: in such a scenario, where pregnancy must either be entirely planned or averted, has there been any halachic precedent for whether the couple should still marital relations, and if so, whether birth control (or at least some forms of the such) is permissible?
This post suggests that the solution isn't to not use birth control or abstain, but I would prefer a more explicit address of the problem.
Note: this sounds like the sort of scenario where the advice to CYLOR would be extremely pertinent, but I am asking purely out of curiosity.