Indications for oocyte (egg) vitrification (fast freezing) include the preservation of reproductive competence of young cancer patients who need chemotherapy, pelvic radiation, or surgical removal of ovaries for treatment. Furthermore, the ability to freeze oocytes allows patients to reduce the number of embryos frozen, thereby circumventing the moral and ethical dilemmas of having left-over embryos in cryostorage. In addition, oocyte cryopreservation could allow women to delay childbearing if they want or need to. Until recently, conventional cryopreservation protocols have remained too inefficient for practical application in an infertility center. Very little is known about the effects of vitrification on oocytes and subsequent embryo development, especially using the sibling model (group of oocytes from the same cohort of ovarian follicles within patient). The purpose of this study is to examine the effect of oocyte vitrification on fertilization rates, embryo quality and development.

Inclusion Criteria:

• healthy women ages 21-37 (inclusive)undergoing IVF in an attempt to achieve pregnancy
• Day 2-4 FSH < 10 IU/ml, LH <12 IU/ml, and E2 <50 pg/ml
• Antimullerian Hormone (AMH) >1.5
• Between 5 and 20 basal antral follicles on day 2-4 of the menstrual cycle
• BMI >18 and <32

Exclusion Criteria:

• Smokers
• Polycystic Ovarian Syndrome (PCO)