Controlled Ovarian Stimulation by HP-hMG for IVF / ICSI Cycles: Study on Ovarian Hyper Stimulation Syndrome in a Cohort of Women From 18 to 36 Years Old.

Inclusion Criteria: * Women who present infertility of more than one year and are candidates for a first or second IVF cycle with or without ICSI for whom HP-hMG is prescribed for COS. * Absence of infertility treatment during the last 3 months before enrolment. * Age: from 18 to 36 years old. * BMI between 18 and 30 kg / m². * Presence of both ovaries accessible to puncture and absence of ovarian or uterine abnormalities. * Male or female infertility. * Ovarian stimulation by HP-hMG with pituitary desensitization by a GnRH agonist or antagonist. * Normal ovarian reserve according to physician habitual evaluation. * Consent to participate of the no-interventional study and signature of the patients' information sheet. Exclusion Criteria: * Presence of a chronic disease, cancer or endocrine disease that could potentially influence the results of the stimulation or that represents a contraindication for ovarian stimulation. * Known endometriosis grade III or IV. * Contraindication to the use of gonadotropins or current pregnancy diagnosed by the clinician. * Recurrent miscarriages, known genetic disease of one of the partners or indication of a preimplantation genetic diagnosis (PGD). * Smoking over than 10 cigarettes / day.´ * Participation in an interventional study at the time of inclusion. * Known poor ovarian response in a previous cycle of stimulation (number of oocyte collected ≤ 3, and / or more than 2 previous IVF/ICSI cycles and / or abnormal result in ovarian reserve test (AMH \< 1 ng/ml with Immunotech equipment or AMH\<0.7 ng/ml with DSL equipment).