Background While single embryo transfer (SET) is widely advocated, double embryo transfer (DET) remains preferable in clinical practice to improve IVF success rate, especially in poor prognosis patients with only poor quality embryos (PQEs) available in addition to one or no good quality embryos (GQEs). Furthermore, previous studies suggest PQE might adversely affect the implantation of a GQE when transferred together. This study aims to evaluate the effect of transferring an additional PQE with a GQE on the outcomes in poor prognosis patients. Methods A total of 5037 frozen-thawed blastocyst transfer (FBT) cycles between January 2012 and May 2019 were included. Propensity score matching was applied to control for potential confounders, and we used generalized estimating equations (GEE) models to identify the association between the effect of an additional PQE and the outcomes. Results Overall, transferring a PQE with GQE (Group GP) achieved significantly higher pregnancy rate (PR), live birth rate (LBR) and multiple pregnancy rate (MPR) than GQE only (group G). The addition of a PQE increased LBR in patients aged 35 and over and in patients who received over 3 cycles of embryo transfer (ET) (48.1% vs 27.2%, OR:2.56, 95% CI: 1.3–5.03 and 46.6% vs 35.4%, OR:1.6, 95% CI: 1.09–2.35), but not in women under 35 and in women who received less than 3 cycles of ET (48.7% vs 43.9%, OR:1.22, 95% CI: 0.93–1.59 and 48.3% vs 41.4%, OR:1.33, 95% CI: 0.96–1.85). Group GP resulted in significantly higher MPR than group G irrespective of age and the number of previous IVF cycles. Conclusions An additional PQE does not negatively affect the implantation potential of the co-transferred GQE. Nevertheless, the addition of a PQE contributes to both live birth and multiple birth in poor prognosis patients. Physicians should still balance the benefits and risks of DET.

Background Estradiol (E2) is an important hormone in women. Changes of serum E2 levels may affect the endometrial receptivity for embryo implantation and thus affect pregnancy outcomes. This study was to assess the association between serum E2 levels on the day of human chorionic gonadotrophin (HCG) administration and live‐birth rates in patients with frozen embryo transfer (FET). Methods Totally 2071 women receiving long protocols of long‐acting gonadotropin‐releasing hormone (GnRH) agonists were enrolled. According to the E2 levels on the day of HCG administration, these patients were divided into four groups: 676 cases of E2 ≤ 3051 pg/mL in Q1 group, 676 cases of 3051 pg/mL < E2 ≤ 4558 pg/mL in Q2 group, 675 cases of 4558 pg/mL < E2 ≤ 6718 pg/mL in Q3 group, and 674 cases of E2 > 6718 pg/mL in Q4 group. The clinical indicators including female age, body mass index (BMI), duration of infertility, infertility styles, treatment protocols, hormone levels, total antral follicle count, endometrial thickness, top‐level embryos, and live‐birth rates were analyzed, and multivariable logistic model was conducted to select significant variables. Results Significant differences were observed for the female age (OR = 0.965, 95% CI: 0.946‐0.985, P < .001), total antral follicle counts (OR = 1.025, 95% CI: 1.008‐1.043, P = .004), transferring what day of embryos (OR = 1.242, 95% CI: 1.137‐1.356, P < .001), endometrial thickness (OR = 1.058, 95% CI: 1.004‐1.115, P = .035), top‐level embryos (OR = 1.416, 95% CI: 1.157‐1.731, P = .001), and E2 levels on HCG day >6781 pg/mL (OR = 1.344, 95% CI: 1.069‐1.690, P = .011) between live‐birth and non‐live‐birth groups. The area under the curve (AUC) for E2 levels on HCG day was 0.558, the sensitivity was 54.75%, and the specificity was 55.10%. Conclusion Serum E2 level on HCG day was an independent predictor of live‐birth achievement in patients with FET.

The embryo transfer depth may affect the chance of pregnancy. However, embryo dislodging caused by uterine contraction may occur after the transfer. The aim of the retrospective study was to investigate whether the factors associated with uterine contractilities, such as endometrial thickness and progesterone elevation, affect the association between transfer depth and implantation. A total of 7849 fresh transfer cycles on conventional stimulation in a single in vitro fertilization (IVF) center during the period 2013–2015 was reviewed. Patients were categorized according to quartiles of embryo transfer depth (≤ 9 mm, n = 1735, 9.1–11 mm, n = 2557, 11.1–14 mm, n = 1933, ≥ 1.4 mm, n = 1624, respectively). Adjusted for confounding factors, the adjusted odds ratio (aOR) (95% confidence interval, CI) for clinical pregnancy was 0.90 (0.79–1.02), 0.86 (0.74–0.99), and 0.70 (0.60–0.82) respectively in quartiles 2 through 4, comparing with quartile 1. However, the aORs were significantly increased when the endometrial thickness was < 8 mm. In comparison with that in the cycles with a normal endometrial thickness (8–11 mm), the aORs comparing quartiles 2 through 4 with quartile 1 in the cycles with an endometrial thickness < 8 mm increased from 0.78 (95% CI 0.65–0.93), 0.79 (95% CI 0.65–0.97), and 0.64 (95% CI 0.51–0.81) to 1.73 (95% CI 1.21–2.47), 1.04 (95% CI 0.69–1.56), and 1.45 (95% CI 0.91–2.31), respectively. In the cycles with elevated progesterone and blastocyst stage transfer, the aORs comparing quartiles 4 with quartile 1 decreased from 0.73 (95% CI 0.62–0.87) and 0.74 (95% CI 0.63–0.87) to 0.58 (95% CI 0.40–0.84) and 0.42 (95% CI 0.25–0.73) than those in the cycles without. However, only blastocyst transfer showed a significant interaction with transfer depth (p = 0.043). Our data suggested that endometrial thickness and blastocyst transfer significantly affect the association between embryo transfer depth and clinical pregnancy.

Objective: To evaluate the effect of transferring a poor quality embryo (PQE) with a good quality embryo (GQE) on the outcomes in poor prognosis patients. Design: Retrospective cohort study. Setting: University-affiliated hospital. Population: A total of 5,037 FBT cycles between January 2012 and May 2019. Methods: Single FBT with GQE were defined as group G and double FBT with GQE plus PQE were defined as group GP. Propensity score matching was applied to control for potential confounders. Multivariate generalized estimating equations (GEE) models were used to identify the association between the effect of an additional PQE and outcomes. Main Outcome Measures: Live births and multiple pregnancies. Results: Group GP resulted in a significantly higher live birth rate (LBR) than group G in women aged 35 and over and in women who received over 3 cycles of embryo transfer (ET) (48.

The embryo position is supposed to affect implantation following embryo transfer. However, embryo dislodging caused by uterine contraction may occurred after transfer. The retrospective study was to investigated whether the factors associated with uterine contractility, such as endometrial thickness and progesterone elevation, affect the association between embryo position and implantation. A total of 7849 fresh transfer cycles on conventional stimulation in a single IVF centre during the period 2013–2015 was reviewed. Patients were categorized according to quartiles of embryo-fundus distance (≤9, 9.1-11, 11.1-14, ≥1.4 mm, respectively). Adjusted for confounding factors, the odds ratio (OR) (95%CI) for clinical pregnancy was 0.90 (0.79-1.02), 0.86 (0.74-0.99) and 0.70 (0.60-0.82) respectively in quartiles 2 through 4, comparing with quartile 1. However, ORs were significantly increased when endometrial thickness was < 8 mm. The ORs comparing quartiles 2 through 4 with quartile 1 increased 1.96 (95%: 1.33-2.90), 1.20 (95%: 0.78-1.87) and 1.98 (95%: 1.20-3.26) fold respectively in cycles with an endometrial thickness < 8 mm than in cycles with a normal endometrial thickness (8-11 mm). Elevated progesterone on the day of hCG and blastocyst stage transfer reduced the ORs. Our data suggested an interaction between patient characteristics and embryo transfer techniques.