Ongoing pregnancy qualifies best as the primary outcome measure of choice in trials in reproductive medicine: an opinion paper.

The most appropriate primary outcome measure for reproductive medicine has been discussed frequently. In 2003 the European Society for Human Reproduction and Embryology recommended that the outcome measure of assisted reproductive technology (ART) and non-ART should be singleton live birth. Although live birth is indeed the aim of clinical practice, and there is no discussion that it should be reported in infertility trials, we hereby provide arguments that plead for using ongoing pregnancy as the primary outcome in such trials. We feel that ongoing pregnancy best serves the many purposes of a primary outcome and best reflects the effectiveness of a treatment.