Abstract
BackgroundThe major difference between a natural cycle and an artificially prepared cycle is the lack of luteinizing hormone (LH) peak in the latter. The LH/hCG receptors were identified to express in human endometrium and evidences of experiments also suggested the beneficial role of hCG in embryo implantation, indicating that the LH peak might be of clinical significance and the activation of LH/hCG receptors in the endometrium could improve embryo implantation. Hence, we postulated that the addition of hCG prior to secretory transformation in an artificial cycle might improve pregnancy outcomes.MethodsThis retrospective cohort study was conducted at a Reproductive Medicine Center between 2016 and 2018. Patients aged ≤43 years at the (index) oocyte retrieval and undergoing artificially prepared frozen-thawed embryo transfer (FET) with at least one good-quality embryo transferred were included. The cycles were divided into two groups: The hCG group (n = 337) received an intramuscular injection of 10,000 IU hCG before secretory transformation; the control group (n = 364) performed FET without hCG administration. The primary endpoint was live birth delivery rate (LBR), secondary outcomes included implantation rate, clinical pregnancy rate (CPR) and ongoing pregnancy rate (OPR).ResultsThe LBR (49.9% vs 39.6%, P < 0.01), CPR (61.4% vs 50.5%, P < 0.01) and OPR (52.8% vs 43.1%, P < 0.05) were statistically significantly higher in the hCG group than the control group. The superiority in LBR after hCG administration remained significant after adjusting for confounding factors (OR 1.613, 95% CI 1.173–2.217; P < 0.01). In the subgroup analysis, the improvement in LBR was statistically significant after hCG administration for cleavage-stage embryo transfer cycles (51.2% vs 42.3%, P < 0.05), whereas for blastocyst transfer cycles, the improvement in LBR was not (45.7% vs 31.3%, P > 0.05).ConclusionsIntramuscular hCG injection prior to secretory transformation may benefit LBR in patients undergoing artificially prepared FET cycles. But it should be noted that nonsignificant tendency towards higher LBR was observed after hCG administration in patients undergoing blastocyst transfer. So, future prospective randomized controlled studies are required to confirm, especially for blastocyst transfer cycles.
Highlights
Successful embryo implantation is a pivotal step for maintenance of pregnancy, it requires optimal synchronization between the endometrial development and embryo
It should be noted that nonsignificant tendency towards higher live birth delivery rate (LBR) was observed after Human chorionic gonadotropin (hCG) administration in patients undergoing blastocyst transfer
486 cycles did not meet the inclusion criteria (279 cycles performing natural cycle or mild stimulation protocol for endometrial preparation, 104 cycles performing artificially prepared frozen-thawed embryo transfer (FET) cycle with GnRH agonists pretreatment before steroid administration, 92 cycles in which no good-quality embryo was transferred and 11 cycles in which the age of patients at the oocyte retrieval patients was more than 43 years) and 29 cycles were excluded for the patients suffering from endometriosis
Summary
Successful embryo implantation is a pivotal step for maintenance of pregnancy, it requires optimal synchronization between the endometrial development and embryo. Human chorionic gonadotropin (hCG), sharing the same receptor as luteinizing hormone (LH), has been used to induce oocyte final maturation or prompt corpus luteum formation by directly acting on LH/hCG receptors in the ovary, traditionally. The LH/hCG receptors were identified to be expressed and be functionally active in human endometrium, with the maximum level in the early-mid secretory phase which exactly covered the “implantation windows” [2]. Of its well-known role in the ovary, hCG may have direct effects on the endometrium by acting on LH/hCG receptor [3, 4]. The LH/hCG receptors were identified to express in human endometrium and evidences of experiments suggested the beneficial role of hCG in embryo implantation, indicating that the LH peak might be of clinical significance and the activation of LH/hCG receptors in the endometrium could improve embryo implantation. We postulated that the addition of hCG prior to secretory transformation in an artificial cycle might improve pregnancy outcomes
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