Brinkett:
Your scenario is easy in some ways, more problematic in others. There is no simple way to do it, but it still could be done. I assume that you want the issue to be one of a woman carrying the pregnancy long enough to produce a viable infant, not one of actual danger to the mother from doing so. I put the issue that way because these days the disorders for which pregnancy would constitute a danger to the mother directly (and thus the child indirectly) do not follow injuries; rather, they generally are medical conditions in the mother such as blood clotting problems, cancer, severe high blood pressure, or diabetes.
If you want an injury that will cause future problems both in getting pregnant and in carrying the pregnancy, then probably direct injury to the uterus is the way to plot it. You could have knife injury to the lower abdomen and pelvis lacerate a woman’s uterus. If the victim were young, the surgeon might be inclined to repair the uterus rather than simply remove it. I would make the uterine injury pretty extensive, not just a slash. Have the surgeon remove part of the wall (maybe 25% or so) of the uterus as part of the repair of her knife injury because the damage was extensive. If the uterus is too small (like 75% of normal), pregnancy usually does not go to term. The problem here is that most trauma surgeons, faced with that situation (extensive knife wounds to the lower abdomen involving the uterus), would just take out the uterus and tell the woman that she can never have children. You could plausibly have a surgeon try to save the uterus by making the trauma surgeon a touchy-feely, sensitive person (maybe a woman who has had trouble herself with pregnancy?), but most trauma surgeons are pretty rough-hewn folks.
The infertility part would be another issue. You could have the injury slash her Fallopian tubes, but that can be repaired unless you make the injury fairly extensive, and you would need to get both of them to make her infertile. Subsequent scarring of the tubes as her injury healed could make her infertile, but the surgeon would not know that until much later. A tricky way could be for her to get a post-operative infection in her pelvis, which is common after injuries like this, particularly if you have the knife nick her intestines as well. The aftermath of the infection could scar her tubes and make her fairly predictably infertile.
But there is a problem with in vitro pregnancy part of your scenario; no infertility specialist is going to implant anything in a women who has a previously damaged uterus, precisely because the pregnancy is unlikely to go to term. So the in vitro thing really would be far-fetched.
So it’s complicated. To me, the best thing would be for the surgeon to save the uterus (which, as I noted, would need some additional explanation), have the tubes damaged by the injury, and have the doctors tell her that it is unlikely that she could get pregnant, and if she did get pregnant, unlikely for her to carry the baby to term. (But not impossible.) Then get her pregnant the old-fashioned way.
Good luck. E-mail me privately if you want to discuss this further.