Introduction
As a continuing conundrum, adenomyosis has besieged clinicians over than one hundred years, which is manifested with displacement of endometrial glands and stroma in the myometrium, surrounded by smooth muscle hyperplasia(1). Adenomyosis can induce a series of clinical problems, such as heavy menstrual bleeding, chronic pelvic pain and infertility. As time passes, the lesions gradually exacerbated, and eventually result in infertility and severe impact on life quality. A cross-sectional study showed that the incidence of adenomyosis was respectively 20% and 29.7% in ≤40 years and >40 years infertile patients (2). In infertile women receiving artificial reproduction technology(ART), the proportion can rise to 30%-40%(3).
The negative effect of adenomyosis on outcomes of ART were accumulated, and persistent endeavors were made to improve the pregnancy outcomes(3-5). So far, ultr-along protocol had received more approvement because of possible improvement on clinical pregnancy rate(CPR) or live birth rate(LBR) (6-9). A widely accepted mechanism was downregulation induced by long acting GnRHa could counter hyperestrogenism and progesterone resistance of adeomyosis. However, ultra-long protocol had an obvious defect, that was, deep inhibition of ovarian function, which usually resulted in the increase of gonadotropin duration and dosage. More seriously, for adenomyosis patients with poorer ovarian reserve, the inhibition of long acting GnRHa could induce poor ovarian response, manifesting with decreased oocyte retrieval and negative pregnancy outcomes. Besides ultra-long protocol, conventional protocols, such as long, antagonist and short protocols all could be adopted, however, systematic evaluation about these protocols was absent. In frozen embryo transfer (FET) cycles, if embryos originating from different protocols, did any differences of pregnancy outcomes exist? There were no answers.
So, we designed this study and tried to systematically evaluate the pregnancy outcomes of different protocols in fresh embryo thansfer (ET) cycles. Additionally, we also aimed to elucidate whether embryo deriving from different protocols could affect the outcomes of FET cycles.