Answer from:
In general terms, we would give people the label of unexplained sub-fertility if they haven’t conceived within a reasonable timeframe with normal assessment. The normal assessment is not a really complex process. It is understood that the woman ovulates on a regular basis, that the man has a reasonably normal sperm test, that they are having reasonably regular intercourse to give themselves the opportunity to conceive and that the woman’s fallopian tubes don’t demonstrate any significant problem. Those are the simple things that we can test more usefully from a fertility point of view and if they’re all normal, but couples continue not to conceive, then we would consider them to have an unexplained other problem. There may not be a problem, but there may be subtle things going on that we can’t necessarily test for in depth. The more complex your assessments go, the less clear they are about what the results may mean. But you may then find things about people that take mount to that unexplained factor, for instance if you take couples through IVF treatment and find no fertilisation when you put eggs and sperm together, there is something fundamental going on there, which might translate to what is going on, on their own, but you can’t know that until you take them down that route. The medical definition is, in simple terms, normal ovulation, normal tubes, normal sperm, regular intercourse, take out the age related factor (but it does come into it as well) and you can have that label of unexplained sub-fertility, having not conceived within a decent time frame. Most people would add the label as an ear mark but you would not then think of treatment until you have been trying for longer because the balance between treatment and your ongoing chances may not actually tip until you’ve not necessarily exhausted your chances but had a decent length of time to try.
