Prognosis-based management of couples with unexplained subfertility

One out of nine heterosexual couples who are trying to conceive, do not succeed within one year of trying. This is referred to as subfertility. In almost half of subfertile couples, no explanation for their inability to conceive can be found during check-ups. This ‘unexplained’ subgroup represents a clinical dilemma: there is no clinical indication that treatment, for instance using in vitro fertilisation, will solve the physical problem, especially given that these couples can still conceive naturally. The pregnancy chance when trying to conceive naturally for a longer period of time i.e. the prognosis is key in deciding (when) to treat. Not all couples benefit from starting treatment immediately. Due to selection, in which couples with a good prognosis conceive and those with a poorer prognosis do not, the average chance of natural conception decreases as couples try to conceive for a longer period of time. This thesis provides individualised prognoses i.e. pregnancy chances after trying to conceive naturally or when starting intrauterine insemination or in vitro fertilisation at various points in time. Predictions were estimated using methods for dynamic prediction. In the absence of a clear diagnosis and a consensus on the best treatment trajectory, couples require prognostic information to make an informed, shared decision with their clinician on fertility treatment. The prognoses in this thesis can facilitate this decision making process and give couples with unexplained subfertility a realistic estimate of what they can expect from their treatment trajectory