Unexplained infertility — ongoing transatlantic debate

A recent US study comparing different drugs for ovarian stimulation in women with unexplained infertility demonstrates that letrozole is less effective than gonadotropins or clomiphene; however, the primary end point for the study was not efficacy but, rather, multiple pregnancy rates. This study confirms, yet again, that gonadotropins are associated with unacceptably high rates of multiple births.