Spontaneous Conception in Couples Who Need Assisted Reproduction Technology Treatment-A Narrative Review

Importance: Most couples who turn to assisted reproductive technology (ART) treatment do so, usually, after giving up emotionally on the chances of conceiving naturally. Others undergo ovulation induction with intrauterine insemination (IUI) and turn to ART after the latter has failed. Spontaneous conception after having experienced the exhausting process of ART, whether it was successful or not, could be very surprising and confusing for many couples. Objective: Review all the scenarios within which an unexpected spontaneous conception can occur and the likelihood of its occurrence. These are four such scenarios: (1) after being referred to ART but before the actual initiation of ART; (2) between ART cycles; (3) after a successful ART pregnancy; (4) after giving up on treatment. We have found only a systematic review on #3, but not the other three. Evidence Review: We collected all PubMed citations for the terms "spontaneous conception" and ART or IVF. Thereafter, we realized that no AI tool can filter only the relevant literature. Hence, we exhausted all possible cross-references by manual search to ensure the completeness of the search. Findings: In each of the four scenarios, spontaneous conceptions occur. Before treatment, a critical element is the length of the waiting time, as is the gap between treatments when already treated, with the cost of treatment being a critical determinant. After the conclusion of treatment, whether successful or failed, the main determinants of the chance for spontaneous conception are age, length of infertility, and the leading etiology for infertility. Overall, the chances range from as little as 2% and up to 25%, with severe male factor and a woman's age being the most notable for low rates. Conclusion and Relevance: Each couple entering ART treatment should be informed of the chances for spontaneous conception, whether as an aid to the decision to enter or the decision to leave after a failure, and on the more cheerful side, to be aware of the chances for unplanned pregnancy after a successful treatment.