Fertility treatments usually convert uni-ovulatory cycles into multi-ovulatory cycles. Consequently, their increased utilization over the last few decades has led to an epidemic of multiple births [1–3]; the majority of these are the consequence of ovarian hyperstimulation/intrauterine insemination (IUI) cycles, rather than in vitro fertilization (IVF) [3,4]. In contrast to IUI cycles, IVF allows for better control of the risk of multiple pregnancy [4,5], as this risk is to a significant degree determined by how many embryos are transferred and given the chance to implant.