Pregnancy outcomes in women with adenomyosis, undergoing artificial endometrial preparation with and without gonadotropin-releasing hormone agonist pretreatment in frozen embryo transfer cycles: An RCT

Abstract Background Selecting a suitable and preferable method for endometrial preparation in frozen embryo transfer (FET) cycles for women with adenomyosis is still challenging in infertility treatment. Objective To compare 2 artificial endometrial preparation regimens with and without gonadotropin-releasing hormone agonist (GnRHa) pretreatment in women with adenomyosis undergoing FET cycles. Materials and Methods This randomized clinical trial study was conducted on 140 adenomyosis cases who underwent FET cycles at Arash Women's hospital, Tehran, Iran from May 2020 to March 2021. Participants were randomly allocated into hormonal replacement therapy (HRT) and HRT+GnRHa pretreatment groups (n = 70/each). Endometrial preparation with 2-6 mg daily estradiol was started in the HRT+GnRHa group, taking after down-regulation with the GnRHa. Within the HRT group, the same dose of estradiol was commenced within the early follicular stage. The main (chemical and clinical pregnancy rates) and auxiliary results (twin pregnancy, miscarriage, and live birth rates) were compared between groups. Results The demographic characteristics and severity of adenomyosis, endometrial thickness, and pattern at starting progesterone administration were similar in the 2 groups, and triple-line endometrium was found to be the dominant pattern in both groups (p = 0.65). No significant differences were observed in chemical, clinical, and twin pregnancy rates as well as miscarriage and live birth rates between groups (p = 0.71, p = 0.81, p = 0.11, and p = 0.84, respectively). However, the total estrogen dose and duration of estrogen consumption were significantly higher in the pretreatment group (p = 0.001, and p = 0.003). Conclusion These results indicated that the hormonal endometrial preparation with estrogen and progestin for FET cycles is as efficacious as a protocol involving preceding pituitary suppression with a GnRHa. Further large randomized clinical studies are required to confirm these findings.


Introduction
Adenomyosis is a benign disease of the uterus defined by the growth of the basal endometrium into the sub-endometrial myometrium (1). Due to postponing pregnancy until the third decade of a woman's life, it is much more recognized among infertile cases who underwent assisted reproductive technology (2). Adenomyosis manifests with dysmenorrhea, menorrhagia, pelvic pain, and an enlarged and tender uterus (3). The conceivable etiology is recommended as disturbance of the typical boundary between the endometrium and the myometrium during physiological recovery and mending of the endometrium, driving to myometrial intrusion by endometrium (4). Endometrial healing activates the immune system, resulting in increased estrogen following microtrauma to the endometrialmyometrial junction and increased uterine peristalsis activity (4,5).
Adenomyosis's effects on fertility remains unclear, even though uterine peristalsis activity negatively affects sperm and embryo transfer (5). Based on the last meta-analysis published on the effect of adenomyosis on pregnancy outcomes following assisted reproductive technology, it is concluded that adenomyosis hurts in vitro fertilization clinical outcomes; therefore, pretreatment with the use of longterm gonadotropin-releasing hormone agonist (GnRHa) or long protocol could be advantageous (6).
Hormonal replacement therapy (HRT) is a common protocol for frozen embryo transfer (FET) cycles because of its more flexible program, enabling physicians to choose the day of embryo transfer suitable for women with or without regular ovulation. This protocol uses estrogen supplementation for endometrial preparation (7,8). Pretreatment with a GnRHa added to the HRT protocol, results in better pituitary downregulation (9). The GnRHa protocol reduces tissue inflammation and angiogenesis and increases the apoptotic index, which improves endometrial receptivity in adenomyosis (5,10).
Local hypoestrogenism is effective in myometrial hyperperistalsis activities and benefits implantation (11,12). There is insufficient evidence to support preferring an endometrial preparation protocol with or without GnRHa for FET in these women.

Sample size
The sample size was estimated to be a minimum of 130 (n = 65/ each) by considering the significance level of 5%, the power of 80%, according to the rate of clinical pregnancy between 2 groups (p1 = 51.35%) (p2 = 24.83%), and used the following formula based on the previous study (11).

Randomization and blinding
Participants were allocated randomly into HRT and HRT+GnRHa pretreatment group (HRT+GnRHa) (n = 70/ each). The block randomization method was designed by the epidemiologist using STATA software, version 13.
The type of study group was placed in a sealed envelope, and when the physicians approved the participants' eligibility for the study, the midwife then delivered the envelope to them. The researcher who followed up on the pregnancy results and the statistician did not know about the study grouping of the participants.

Endometrial pattern evaluation
The endometrial pattern was determined

Outcomes
The primary outcomes were chemical (positive beta human chorionic gonadotropin test 14 days after ET) and clinical pregnancy (the presence of at least 1 fetus with heart activity at 4-6 wk following ET) rates. Secondary outcomes, including twin pregnancy, miscarriage, and live birth rates, were followed up and reported. A twin pregnancy was detected on observation of 2 gestational sacs and the fetal poles with heartbeat in an ultrasound examination at 6-7 wk following ET.
The miscarriage rate is considered as the loss of a clinical pregnancy before 20 wk of gestation.
Live birth was defined as the delivery of a fetus that shows evidence of life after being entirely outside of the uterus, regardless of the duration of pregnancy. The pregnancy outcomes were reported per ET cycles, and twin births were considered as one live birth.

Results
Among  (Table I).
In the follow-up, the chemical pregnancy, clinical pregnancy rates, as well as twin pregnancy, miscarriage, and live birth rates were found to be comparable between groups (p > 0.05) ( Table   II). All possible related factors were entered in the multivariable logistic regression model to independently identify the significant predictive factors to the clinical pregnancy rate. No significant variables were found (Table III).    (23,24).
The design of a clinical trial with a significant sample size is the strength of the present study.
It was ideal to transfer a single euploid blastocyst to control the embryo quality factor; however, we could not apply this factor in our study due to limitations. Since the 2 groups were homogeneous in terms of baseline characteristics and no significant variable affecting clinical pregnancy was found in logistic regression tests, the findings of the present study are reliable.

Conclusion
The present study indicated that endometrial preparation for FET with and without suppression by GnRHa provides similar results in pregnancy outcomes. Moreover, the HRT cycle time interval to embryo transfer is shorter, so this protocol is much simpler, better, and more cost-effective than the HRT cycle with GnRHa pretreatment.
Furthermore, prospective RCTs are needed to validate the optimal protocol for FET cycles in cases with adenomyosis.