Should we still offer elective freezing of all embryos in all IVF cycles?

Elective 'freeze all', also called 'freeze only', refers to an IVF cycle where all embryos are frozen for later embryo transfer in a non-stimulated cycle, with the promise of increased success rates and prevention of ovarian hyperstimulation syndrome (OHSS) in most patients. However, 'freeze all' is associated with significantly higher perinatal complications including eclampsia, preeclampsia, chronic hypertension and large-for-gestational-age infants, without the demonstrated advantages of providing better results, except for a decrease in the incidence of OHSS, which should matter to women with polycystic ovary syndrome (PCOS) and high responders to ovarian stimulation but not to all patients. 'Freeze all' is also suggested for all simulated IVF cycles, due to the alleged 'faulty endometrium' caused by ovarian stimulation. However, there is no direct evidence that asynchronous endometrium exists, and only if preovulatory progesterone level increase, can 'freeze all' confer an advantage. We conclude that an alleged diagnosis of 'faulty endometrium' should not be used as an indication for 'freeze all'. To offset the risk of OHSS more simply, less costly and less risky solutions such as mild ovarian stimulation, to dampen the number of oocytes and to aim for transfer of a single blastocyst, should be the preferred solution to treat women with PCOS and high responders for oocyte retrieval.