Follicle stimulating hormone or clomiphene citrate in intrauterine insemination with ovarian stimulation for unexplained subfertility: a role for treatment selection markers?

Research question: Can women be identified, on the basis of baseline patient characteristics, as having better chances of an ongoing pregnancy with FSH instead of clomiphene citrate as stimulation agent in intrauterine insemination for unexplained subfertility? Design: A secondary analysis of a multicentre randomized controlled superiority trial; the SUPER study. Between July 2013 and March 2016, couples with unexplained subfertility undergoing intrauterine inemination (IUI)were allocated to an FSH or clomiphene citrate group. Female age, body mass index, duration of subfertility, primary versus secondary subfertility, antral follicle count and total motile count were assessed. For each of these factors, a logistic regression model was developed to assess if different estimated effects of FSH versus clomiphene citrate on ongoing pregnancy occurred within strata of each factor. Results: A total of 684 couples received 2259 IUI cycles; 338 couples were allocated to FSH, of which 84 conceived leading to ongoing pregnancy and 346 couples were allocated to clomiphene citrate, of which 71 conceived leading to ongoing pregnancy. None of the treatment selection markers was associated with better ongoing pregnancy chances after IUI with FSH compared with clomiphene citrate. Conclusion: In couples with unexplained subfertility undergoing IUI, no baseline treatment selection markers could be identified to determine whether ovaries should be stimulated with FSH or clomiphene citrate.