The purpose of this study is to determine the best way to freeze eggs in order to preserve the fertility potential of young women.

Human egg freezing is rapidly becoming a vital tool in Assisted Reproductive Technology. Candidates for egg freezing include women without partners who wish to preserve their fertility; cancer patients at risk of losing fertility from chemotherapy; and donor egg recipients. While in the past, egg freezing has not been as successful as embryo freezing in producing live births, recent experience in several centers has demonstrated significant improvement, with pregnancy rates comparable to those achieved with frozen embryos. The purpose of this study is to determine the best method to freeze eggs. We shall be seeking volunteers from the egg donor program, since young, fertile donors represent the best model to study the effect of egg freezing.

We plan to enroll 12 recipients and 6 donors in this study. Each egg donor will go through a stringent screening process (medical, genetic and psychological). Eggs retrieved from all donors will be split in half: one half will be frozen by the slow freeze method, and the other half by vitrification. Each of the six donors will be paired with two recipients; each recipient will be assigned half the total eggs frozen. For each recipient, half of the eggs will come from the slow freeze group and the other half will come from vitrification.

When the recipient's uterine lining is deemed ready (following estrogen treatment and ultrasound monitoring), thawing will be performed on eggs frozen by either the slow freeze or the vitrification method. The thaw process will be randomized between the two types of freezing. One sperm will be injected into each egg that survived the freeze. Fertilization and embryo development will be recorded. Ideally, two embryos will be transferred into the recipient's uterus. Pregnancy will be determined by a blood test and followed by serial blood tests and ultrasound.

The study will determine which freezing method yields better survival and pregnancy rates.

Inclusion Criteria:

• donors: women ages 21-32 who wish to donate their eggs; must pass medical, physical and psychological screening.
• recipients: women under the age of 50 who wish to have eggs donated to them through the Donor Egg Program and who aslo pass the medical, physical and psychological screening.

Exclusion Criteria:

• donors: those who do not pass the genetic screening or psychological testing, as described below
• recipients: those who do not pass the screening.

The genetic screening of donors will involve the following:

• All donors will be screened for Cystic Fibrosis, Fragile X and Spinomuscular Atrophy (SMA).
• In addition, donors of Ashkenazi Jewish origin will be screened for Gaucher's disease, Canavan,Tay -Sachs, Familial Dysautonomia, Niemann Pick, Fanconi's Anemia, Bloom and Mucolipidosis Type IV.
• Donors of African-American origin will be screened for Sickle-Cell disease.
• Donors of Asian, Mediterranean, Latino or Hispanic origins will be screened for Thalassemia.

Recipient Screening: A Reproductive Endocrinologist (RE) at the Center will take a detailed history and perform a physical examination on all potential recipients. The RE will assess the health of the potential recipient in order to assess her capacity to carry a pregnancy. Previous IVF cycles, successful or unsuccessful, will have no implication on recipient selection.

The recipient and her partner (if applicable) will meet with the program psychologist. The psychological evaluation is detailed below.

Psychological evaluation: A psychological evaluation will be conducted of the Recipient, her partner (if applicable) and the Donor. The purpose of these evaluations is to determine the suitability of the parties to participate in the Donor Egg Program. Psychological tests will be administered by the Center as part of the evaluation process.

These evaluations may result in a recommendation that one and/or all of the parties not participate in the Donor Egg Program. The psychologist will not be providing any advice or treatment to the Donor or Recipient(s). Nor will the Donor or Recipient(s) be entitled to the results of the Psychologist's evaluation. The Psychologist will provide the results of his/her evaluations to the Center for Human Reproduction.

As with our standard Donor Egg Program practices, there will be an upper age limit of 50 years for all recipients participating in the study.