Before enrollment, suspended due to changing insurance coverage of study drugs.

The aim of this study is to test the hypothesis that the pregnancy rates of women (ages 18-50 years) undergoing transfer of vitrified-warmed blastocysts (frozen at less than 41 years of age) as part of their IVF treatment are not different with respect to the administration of progesterone (Crinone® 8% vaginal gel versus intramuscular progesterone).

The hypothesis of this study is that the type of progesterone administered (intramuscular progesterone or Crinone® 8% vaginal gel) does not affect implantation and clinical pregnancy rates in women receiving cryo-thawed blastocysts that were produced using their own eggs and frozen before age 41 years. Both intramuscular progesterone (25-100 mg compounded in oil) or vaginal progesterone (Crinone® 8% vaginal progesterone gel) are widely used for luteal phase support in patients receiving vitrified-warmed embryos. Crinone® 8% is FDA approved for progesterone supplementation or replacement as part of an Assisted Reproductive Technology (ART) treatment for infertile women with progesterone deficiency (FDA approval letter, 1997).

Inclusion Criteria:

• Signed informed consent
• Patient age at time of embryo freezing: 18 to 40.9 years
• Patient age at embryo transfer: 18 to 50 years (i.e. women currently ages 18-50 years who are transferring embryos created using eggs retrieved from women aged 18-40.9 years)
• Blastocysts frozen by vitrification at Brigham and Women's Hospital
• Standard eligibility criteria for blastocyst transfer at Brigham and Women's Hospital

Exclusion Criteria:

• Fresh or cleavage-stage embryo transfer planned
• Gestational carrier cycles
• Natural and modified natural cycles
• Embryos frozen more than once or derived from thawed oocytes
• Embryos frozen at centers other than Brigham and Women's Hospital
• Embryos frozen using techniques other than vitrification (i.e. slow frozen)
• Patients with recurrent pregnancy loss, defined as failure of 3 or more clinical pregnancies
• Uterine factor infertility: Asherman's, submucosal fibroids, polyp greater than 1 cm at time of embryo transfer, uninterrupted hydrosalpinx
• Patients with three prior failed embryo transfers (fresh or frozen)
• BMI<18 or >40 kg/m2 at screening
• Currently breast feeding or pregnant
• Embryo biopsy performed
• Current smoking, alcohol or illicit drug use
• Allergy to study drugs
• Refusal or inability to adhere to study protocol
• Participation in other experimental drug trials concurrently within the past 60 days