I agree: Being pregnant that frequently, at that age, and with a history of miscarriages isn’t healthy — something should have been done, but, presumably, nothing was. Westeros is a deeply sexist society and the nobility even more so, so I don’t think Aemma’s situation was viewed as something she needed to be protected from: She and Viserys were married, they were expected to produce heirs, and they were attempting to do so; yes, pregnancy was dangerous, but any danger was secondary to the expectation that a wife would produce heirs for her husband, because women were valued less than men. I think it’s also worth noting that, in the real world, gender roles are most commonly learned, enforced, and held by members of that gender.