Effect of transdermal estradiol on endometrial preparation in frozen-thawed embryo transfer

INTERVENTION: Comparison of the effectiveness between transdermal estradiol and oral estradiol on the endometrium of frozen embryo transfer (FET) at Hung Vuong Hospital between January 2020 to August 2021. Patients who indicated frozen‐thawed embryo transfer, have at least one excellent/good frozen embryo before thawing, age 18‐45 years will be invited to participate in the trial. A list of randomized groups will be divided using www.random.org software – Appendix 4. The block randomization method (2, 4, 6, 8) and the permutation block size were used. A randomized staff who is outside the study will print the forms with consecutive signs A and B, which are placed into sealed envelopes and randomly assigned following the result table in Appendix 4. Each individual participating in the study has an equal probability (1:1) to be selected for the sample, using drawing method after screening and signing a consent form. Then, the envelopes will be numbered in ascending order from top to bottom. Participants were grouped in turn according to the open of envelope with the form inside and then received drugs as follow: A: oral estradiol B: transdermal estradiol All members including doctors, midwives, staff were blinded to the randomized table. The pharmacists who provide drugs for patients are not blinded to the drug but they do not play any role in this study. Related interventions: Study group: Transdermal estradiol regimen 1. Begin at day 3 of the menstrual cycle, daily 5 g dosage during 7 days which is equivalent to 1 transdermal dosage twice a day. 1 ruler dosage equals to 2.5 g 2. Perform an ultrasound scan at day 10 of the menstrual cycle: CONDITION: Women undergoing IVF ; Pregnancy and Childbirth PRIMARY OUTCOME: ; 1. Thickness and shape of endometrium measured using vaginal ultrasound examination at baseline and on progesterone day; 2. Serum estradiol concentration measured using immunoassay on progesterone day; 3. Mean duration of treatment, recorded at time of procedure; SECONDARY OUTCOME: ; 1. Cycle cancellation rate of FET measured from medical records at the time of the patient who is indicated to cancel FET cycle such as insufficient endometrial thickness, loss of embryo viability during thawing, other; 2. Implantation rate (number of gestational sacs containing a living embryo implanted in the uterus divided by the number of embryos transferred) measured from medical records 6 weeks after embryo transfer; 3. Clinical pregnancy rate as measured by rising beta hCG levels starting at 14 days post embryo transfer, presence of gestational sac at 6‐7 weeks post embryo transfer, and presence of fetal heartbeat at 6‐7 weeks post embryo transfer; INCLUSION CRITERIA: 1. Women aged 18‐45 2. No history of uterine intervention: suction or endoscopy 3. Has FET indication 4. Has at least one excellent/good frozen embryo before thawing 5. No pathological background: diabetes, high prolactin level, thyroid disorders, adrenal gland disorders. 6. Agree with FET indication 7. Volunteer to the study and has full contact information