Infertility is defined as a failure to conceive after at least 1 year of regular unprotected intercourse [1]. It affects approximately 10 % of couples in their reproductive lives [2,3]. Unexplained infertility is defined as infertility without any demonstrable cause after the basic fertility workup, including assessment of ovulation, semen analysis and evaluation of tubal patency. The incidence of infertility is increasing in the developed world mainly due to postponement of maternity. After a basic fertility workup, about 25 % of couples will be diagnosed with unexplained infertility [4,5].As in unexplained infertility, a causal explanation for the failure of conception is by definition lacking; natural conception should never be excluded in couples diagnosed as such. Consequently, expectant management (EM) may be a good option, especially when the prognosis for natural conception is reasonable.
The EvidenceA recent update of a Cochrane review on intra uterine insemination (IUI) for couples with unexplained infertility was published in 2012 [6]. One trial was included that compared IUI in a natural cycle with EM and showed no evidence of increased live births (334 women: OR 1.6, 95 % CI: 0.92-2.8).Two trials compared EM with IUI with ovarian stimulation (OS) and both concluded there was no evidence of a difference in pregnancy rate (in total 304 women: data could not be pooled) [6]. In the last comparison (IUI-OS versus EM) one large multicentre randomised controlled trial (RCT) from the Netherlands was included. This RCT randomised 253 couples with unexplained infertility and intermediate prognosis of natural conception between either 6 months of EM or immediate start with OS and IUI. Within 6 months, the ongoing pregnancy rate in the EM group was 27 % and in the OS group with IUI 24 % (RR 0.85 CI: 0.63-1.1) [7]. The couples were then treated according to the centre's standard protocol, usually OS with IUI, followed by IVF. Three years after randomisation, the cumulative ongoing pregnancy rates were 72 and 73 % for EM and OS with IUI, respectively (RR 0.99 (95 % CI: 0.85-1.1). The time of ongoing pregnancy also did not differ between groups (log-rank test, p = 0.98) [8]. An RCT from the UK included 334 couples with unexplained infertility that were randomised to EM, oral clomiphene citrate or unstimulated IUI. After 6 months, a live birth rate of 23 % was obtained in the IUI group versus 16 % in the EM group, which was not significantly different (OR 1.60, 95 % CI 0.92) [9].A systematic Cochrane review on in vitro fertilisation (IVF) for couples with unexplained infertility concluded that the added value of IVF in relation to EM or IUI with or without OS in couples with unexplained infertility has not been conclusively proven due to a paucity of data: only one trial with 51 women compared IVF with EM and the live birth rate per woman was significantly higher with IVF (45.8 %) compared to EM (3.7 %; OR 22, 95 % CI 2.5-189) [10].Thus, RCTs in couples with unexplained infertility comparing EM with IUI with or with...