Ovulation Trigger Strategies in Low Ovarian Reserve (TRIGGERBEST)

This study aims to compare different ovulation triggering strategies in women with low ovarian reserve undergoing fresh in vitro fertilization (IVF) cycles. Ovulation triggering is a key step in IVF treatment, as it determines final oocyte maturation prior to oocyte retrieval. Participants are randomly assigned to one of three ovulation trigger approaches: human chorionic gonadotropin (hCG) alone, follitropin delta combined with hCG, or dual trigger using a gonadotropin-releasing hormone (GnRH) agonist plus hCG. The primary objective is to evaluate wether adding follitropin delta at the time of triggering increases the number of matura oocytes obtained, without adversely affecting implantation rates. Pregnancy otucomes following fresh embryo transfer will also be assessed. The results of this study may help optimize ovulation triggering strategies in women with low ovarian reserve undergoing IVF treatment.

Inclusion Criteria: * Signed informed consent. * Women aged between 18 and 42 years. * Primary infertility. * Women with low ovarian response classified within one of the groups defined by the POSEIDON criteria. Exclusion Criteria: * More than two previous failed ovarian stimulation cycles. * Female age \>42 years. * Body mass index (BMI) \>35 kg/m². * Criteria of extremely low ovarian reserve according to the Spanish National Health System exclusion criteria (AMH \