In this prospective randomized trial, the parameters of the frozen-thawed embryo transfer (FET) cycles were analyzed. This study was undertaken in the Department of Assisted Reproductive Technologies and Reproductive Genetics Center at Istanbul Memorial Hospital with approval of the local ethics committee. The aim of this prospective randomized clinical trial was to compare two methods of endometrial preparation for FET, oral estradiol and estradiol transdermal patch.

In this prospective randomized trial, the parameters of the frozen-thawed embryo transfer (FET) cycles were analyzed. This study was undertaken in the Department of Assisted Reproductive Technologies and Reproductive Genetics Center at Istanbul Memorial Hospital with approval of the local ethics committee. The aim of this prospective randomized clinical trial was to compare two methods of endometrial preparation for FET, oral estradiol and estradiol transdermal patch.

A total number of 317 patients who underwent frozen -thawed embryo transfer cycles were enrolled in this study and randomized to two groups including 160 patients with the usage of 6 milligrams/day oral estradiol and 154 patients with the usage of 3.9 milligrams estradiol transdermal patch. Randomization was done with http://www.randomization.com. The patients were given sufficient information to provide written informed consent. All the women underwent intracytoplasmic sperm injection (ICSI).

Treatment protocols: All the patients selected for the research were primed for a frozen transfer using two different ways of exogenous steroid therapy.

In the study group with transdermal route (n=154), 3.9 milligrams of estradiol transdermal patch was applied every other day from the second day of menstruation cycle, and each patch was removed after day. In the control group with oral route (n=160), at the time of cycle, 6 milligrams of oral estradiol valerate was started daily. In both groups, clinical monitoring was done by transvaginal ultrasound from the 11th day of the cycle to measure endometrial thickness. If endometrial thickness was more than 7 millimeter, 90 milligrams vaginal natural progesterone was added. Embryo transfer was done after 5 days.

The primary outcome measure was endometrial thickness on the day of progesterone administration. The secondary outcome measures were chemical and clinical pregnancy, implantation rates, abortion rates, live birth rates, and cycle cancellation rate.

Inclusion Criteria:

• All the women with at least one day 5 or 6 blastocyst
• Appropriate endometrial thickness is more than 7 millimeters on the 14th day of artificial endometrial preparation cycle
• Age under 38 years
• Follicle stimulating hormone less than 12 IU/Liter
• No more than 2 previous treatment cycles
• No history of recurrent spontaneous abortions

Exclusion Criteria:

• Polycystic ovarian syndrome (> 30 cumulus oocyte complexes retrieved at the pick-up)
• Endocrine or metabolic disorder
• Endometriosis
• Embryos derived from donated gametes
• Any underlying diseases (kidney, liver or heart diseases)
• Bad-quality embryos
• Uterine malformation
• Endometrial polyp
• Severe male factor (Azoospermia)
• Body mass index more than 30
• Thrombophilia