In general, nearly 85% of retrieved oocytes are mature and reproductively useful after the retrieval, whereas the remaining percentage are still at metaphase I or germinal vesicle stage (MI: 4% and GV: 11 %, respectively).

The objective of our study is to assess if immature oocytes co-cultured with autologous cumulus cells is a safer strategy than just leaving the oocytes in standard culture.

Under controlled ovarian stimulation, patients with normal functional ovarian reserves produce a good number of oocytes at retrieval. However, in addition to quantity, oocyte maturity is an important variable for the success of reproductive technologies. In general, nearly 85% of retrieved oocytes are mature and reproductively useful, whereas the remaining percentage are still at metaphase I or germinal vesicle stage (MI: 4% and GV: 11 %, respectively). Due to the limited expectations held for in vitro maturation in said stimulated cycles, the rescue of immature oocytes is not widely used in current clinical practice and these oocytes are usually discarded due to the possibility of abnormal embryonic development or an increased rate of abortion.

The objective of our study is to assess if immature oocytes co-cultured with autologous cumulus cells is a safer strategy than just leaving the oocytes in standard culture.

Inclusion Criteria:

• 18-35-year-old women
• BMI: >18 and < 30 kg/m2
• Normal female karyotype
• Normal uterus and ovaries at transvaginal ultrasound

Exclusion Criteria:

• > 35 years
• PCO syndrome carriers
• Null follicle aspiration
• History of chemotherapy or radiotherapy

Mature ooocytes from the same donors, will be used as control group.