No important differences were observed between the LPE and LPL groups and between the HPE and HPL groups for all controlled variables (Table 1): age of the female, gravidity, parity, duration of infertility, ovarian reserve determined by AMH, peak estradiol level, number of transferred embryos, diagnostic criteria (such as female pathology, endometriosis, ovarian dysfunction and PCOS), male pathology, stimulation protocol, number of cancellations, number of failed fertilisations and the experience of the physician performing the embryo transfer. Here, LPL is linked to endometriosis.