Retrospective cohort study on preparation regimens for frozen embryo transfer

Abstract

Objective: To examine the pregnancy outcomes from frozen embryo transfer (FET) cycles using different endometrial preparation regimens, compared to ovulation induction with letrozole (letrozole OI). Design: Retrospective cohort study. Setting: Fertility centre in Sydney, Australia. Patient(s): 6060 frozen embryo transfer cycles. Interventions: Cycles were stratified into one of four ways to achieve endometrial preparation. These were either a natural, letrozole OI, OI with follicle stimulating hormone (FSH OI) or a programmed cycle. Main Outcome Measure(s): The primary outcome was live birth rate per embryo transfer (LBR). Secondary outcomes included clinical pregnancy and biochemical pregnancy rates, adverse events including miscarriage, ectopic pregnancy, stillbirth, neonatal death and multiple births. Ovarian stimulation parameters were also analysed including time taken to reach the luteal phase and the number of blood or urine tests required for monitoring of the cycle. Results: The LBR following letrozole OI cycles was higher when compared to natural cycles (OR 1.27 (1.07 – 1.49)) and programmed cycles (OR 2.36 (1.67 – 3.34)). There was no significant difference between letrozole OI and FSH OI LBR (OR 0.99 (0.76 – 1.28)). An improved LBR with letrozole OI compared to natural cycles was maintained when only women with a normal length cycle were considered (OR 1.44 (1.10 – 1.89)). There was a significant reduction in miscarriage rates when letrozole OI was compared to programmed cycles (OR 0.46 (0.26 – 0.83)). Conclusion(s): The use of letrozole OI for endometrial preparation in an FET cycle may be associated with higher LBR and lower miscarriage rate, compared to using a programmed cycle.

Review of Endometrial Receptivity Array: A Personalized Approach to Embryo Transfer and Its Clinical Applications

“…Lastly, after adjustments to the timing of FET were made for patients found to be pre-receptive or post-receptive, there was a pregnancy rate of 33.3%, which is comparable to the 35.2% pregnancy rate of the control group. Several studies have also indicated a clinical pregnancy rate of about 34% for non-ERA FET, thus showing this to be similar to the findings in the literature [64,65]. Since the pregnancy rates were comparable in both the control and ERA groups, the study concluded that having patients undergo ERA testing before FET shows no improvement in pregnancy rates in patients with zero or some implantation failures.…”

Risk of stillbirth and neonatal death in singletons born after fresh and frozen embryo transfer: cohort study from the Committee of Nordic Assisted Reproduction Technology and Safety

“…Previous studies indicate lower risk of hypertensive disorders in pregnancies with no endometrial preparation (natural cycles),( 39 ) but similar risks of both stillbirth and neonatal death in pregnancies conceived in natural, programmed and stimulated frozen-ET cycles. ( 40 ) ( 39 )…”

“…We had no data on endometrial preparation in frozen-ET. Previous studies indicate low risk of hypertensive disorders in pregnancies with no endometrial preparation (natural cycles) (39), but similar risks of both stillbirth and neonatal death in pregnancies conceived in natural, programmed, and stimulated frozen-ET cycles (39,40) Implications Despite the high risk of adverse perinatal outcomes in ART pregnancies, including preterm birth, low birth weight, and placental complications as shown previously in this study population (18,29,41), we found no increased risk of stillbirth in ART-conceived pregnancies. In contrast, neonatal mortality was higher after both fresh and frozen-ET compared with singletons conceived without medical assistance; however, the high risk attenuated in analyses according to the gestational age.…”

Comparative Efficacy of Various Forms of Estrogen-Containing Drugs for Endometrial Preparation During Frozen Embryo Transfer in Protocols with Hormone Replacement Therapy

“…Пероральный прием эстрогенов может предрасполагать к образованию камней в желчном пузыре в связи со снижением синтеза желчных кислот. Кроме того, повышение уровня эстрона может способствовать увеличению коэффициента насыщения желчи и, следовательно, снижению растворимости желчных кислот [8][9][10][11][12][13][14].…”

“…Трансдермальное нанесение эстрадиола на кожу обеспечивает постепенное прогредиентное поступление активного вещества в кровоток, что поддерживает относительно постоянную концентрацию без сильно выраженных пиков. Более физиологичное соотношение эстрадиола и эстрона наблюдается при трансдермальном применении, что более точно воспроизводит ситуацию, характерную для яичникового цикла[8][9][10][11][12][13][14].Изучены фармакокинетические параметры разных препаратов эстрогенового ряда в форме пластыря, геля, таблеток. Абсорбция геля (17β-эстрадиола) в дозе 1 г сопоставима с одной таблеткой эстрадиола валерата 2 мг.…”