Answer from: Jane Stewart, MD
Because unexplained subfertility is not an absolute thing and because we don’t have a diagnosis as such, it is more a label to do with chances and risks. We need to decide how to best improve people chances, so for couples who have been trying for a couple of years, most people would have conceived, mainly young couples, and so what actually is reasonable, you can say there has been no cause found so you can carry on trying, there is no fertility problem here. We would consider couples at that point to be outliers statistically and we use IVF as a tool to managed unexplained subfertility because it allows us to understand more, it gives us some diagnostic information but it then also can enhance the chances over a short period of time of pregnancy for those couples who a more limited chance now that they have gotten to that point in their trying story. IVF can be successful because it puts eggs and sperm in close proximity which allows us to make sure that fertilisation has happened where it might not be happening naturally. It allows us to pick up problems with fertilisation which we wouldn’t know in any other way. It allows us to adapt that subsequent treatment if we find the specific problems. It bypasses the fallopian tubes, we manipulate the uterus to a certain degree as well so there are a number of things that we are changing through IVF, so although for most people we are still not saying that is why you are not getting pregnant on your own, we may still be enhancing chances with what they are doing naturally, at least over a period of time. It is not for everyone, but if people want to use that as a rule then that is where we would go with it.