Vaginal Compared to Intramuscular Progesterone for Frozen Embryo Transfer

The purpose of this ongoing study is to look at whether Endometrin® (vaginal micronized progesterone tablets) supplemented by intramuscular injection of progesterone in oil (PIO) work as well as PIO alone for women undergoing transfer of frozen-thawed blastocyst(s). Another goal of the study is to determine whether patients prefer Endometrin or PIO. Endometrin® has been approved by the United States Food and Drug Administration, or FDA, "to support embryo implantation and early pregnancy by supplementation of corpus luteal function as part of an Assisted Reproductive Technology (ART) treatment program for infertile women." (FDA New Drug Approval Letter, Endometrin®, 2007). The use of Endometrin® (vaginal micronized progesterone tablets) in this study is investigational. An investigational use is one that is not approved by the U.S. Food and Drug Administration (FDA). Approximately 1170 women between the ages of 18-48 who are having difficulty becoming pregnant and wish to undergo frozen embryo transfer will be asked to participate. The participants will be recruited from among patients of Shady Grove Fertility. One-half of the participants who qualify and wish to take part in the ongoing study will be randomized (assigned by chance, like the flip of a coin) to receive Endometrin® and an intramuscular injection of PIO every third day. One-half will be randomized to receive an intramuscular injection of PIO every day. This study is a type of study called an "open label," assessor-blind study. This means that you and your doctor will know which treatment you are assigned and receive; however, the person analyzing the information obtained from the study will not know which patients received which study treatments. Patients enrolling in the study will receive the medications for their frozen embryo transfer cycle free of charge.