In high responding patients undergoing an initial IVF cycle, elevated estradiol on the day of hCG has no effect on live birth rate

High estradiol levels in fresh embryo transfer cycles are not associated with detrimental impact on birth outcomes

PURPOSE

There is an unclear relationship between estradiol levels and fresh embryo transfer (ET) outcomes. We determined the relationship between estradiol on the day of trigger, in fresh ET cycles without premature progesterone elevation, and good birth outcomes (GBO).

METHODS

We identified autologous fresh ET cycles from 2015 to 2021 at multiple clinics in the USA. Patients with recurrent pregnancy loss, uterine factor, and elevated progesterone on the day of trigger (progesterone > 2 ng/mL or 3-day area under the curve > 4.5 ng/mL) were excluded. The primary outcome was GBO (singleton, term, live birth with appropriate weight). Log-binomial generalized estimating equations determined the likelihood of outcomes.

RESULTS

Of 17,608 fresh ET cycles, 5025 (29%) yielded GBO. Cycles with estradiol ≥ 4000 pg/mL had a greater likelihood of GBO compared to cycles < 1000 pg/mL (aRR = 1.32, 95% CI 1.13-1.54). Pairwise comparisons of estradiol between < 1000 pg/mL versus 1000-1999 pg/mL and 1000-1999 pg/mL versus 2000-2999 pg/mL revealed a higher likelihood of GBO with higher estradiol (aRR 0.83, 95% CI 0.73-0.95; aRR 0.91, 95% CI 0.85-0.97, respectively). Comparisons amongst more elevated estradiol levels revealed that the likelihood of GBO remained similar between groups (2000-2999 pg/mL versus 3000-3999 pg/mL, aRR 1.04, 95% CI 0.97-1.11; 3000-3999 pg/mL versus ≥ 4000 pg/mL, aRR 0.96, 95% CI 0.9-1.04).

CONCLUSION

In fresh ET cycles, higher estradiol levels were associated with an increased prevalence of GBO until estradiol 2000-2999 pg/mL, thereafter plateauing. In fresh ET candidates, elevated estradiol levels should not preclude eligibility though premature progesterone rise, and risk of ovarian hyperstimulation syndrome must still be considered.

The pathophysiological role of estrogens in the initial stages of pregnancy: molecular mechanisms and clinical implications for pregnancy outcome from the periconceptional period to end of the first trimester

BACKGROUND

Estrogens regulate disparate female physiological processes, thus ensuring reproduction. Altered estrogen levels and signaling have been associated with increased risks of pregnancy failure and complications, including hypertensive disorders and low birthweight babies. However, the role of estrogens in the periconceptional period and early pregnancy is still understudied.

OBJECTIVE AND RATIONALE

This review aims to summarize the current evidence on the role of maternal estrogens during the periconceptional period and the first trimester of pregnancies conceived naturally and following ART. Detailed molecular mechanisms and related clinical impacts are extensively described.

SEARCH METHODS

Data for this narrative review were independently identified by seven researchers on Pubmed and Embase databases. The following keywords were selected: 'estrogens' OR 'estrogen level(s)' OR 'serum estradiol' OR 'estradiol/estrogen concentration', AND 'early pregnancy' OR 'first trimester of pregnancy' OR 'preconceptional period' OR 'ART' OR 'In Vitro Fertilization (IVF)' OR 'Embryo Transfer' OR 'Frozen Embryo Transfer' OR 'oocyte donation' OR 'egg donation' OR 'miscarriage' OR 'pregnancy outcome' OR 'endometrium'.

OUTCOMES

During the periconceptional period (defined here as the critical time window starting 1 month before conception), estrogens play a crucial role in endometrial receptivity, through the activation of paracrine/autocrine signaling. A derailed estrogenic milieu within this period seems to be detrimental both in natural and ART-conceived pregnancies. Low estrogen levels are associated with non-conception cycles in natural pregnancies. On the other hand, excessive supraphysiologic estrogen concentrations at time of the LH peak correlate with lower live birth rates and higher risks of pregnancy complications. In early pregnancy, estrogen plays a massive role in placentation mainly by modulating angiogenic factor expression-and in the development of an immune-tolerant uterine micro-environment by remodeling the function of uterine natural killer and T-helper cells. Lower estrogen levels are thought to trigger abnormal placentation in naturally conceived pregnancies, whereas an estrogen excess seems to worsen pregnancy development and outcomes.

WIDER IMPLICATIONS

Most current evidence available endorses a relation between periconceptional and first trimester estrogen levels and pregnancy outcomes, further depicting an optimal concentration range to optimize pregnancy success. However, how estrogens co-operate with other factors in order to maintain a fine balance between local tolerance towards the developing fetus and immune responses to pathogens remains elusive. Further studies are highly warranted, also aiming to identify the determinants of estrogen response and biomarkers for personalized estrogen administration regimens in ART.

Estradiol on trigger day: Irrelevant to live birth rates of fresh cycles but positively associated with cumulative live birth rates

OBJECTIVE

To assess the effects of estradiol (E2) on trigger day on cumulative live birth rates (CLBRs), and pregnancy outcomes after fresh and frozen-thawed embryo transfer (FET).

METHODS

This multicenter retrospective cohort study included 42 315 patients from five reproductive centers. Six subgroups were divided according to E2 on trigger day (<1000, 1000-2000, 2000-3000, 3000-4000, 4000-5000, >5000 pg/mL). Smooth curve fitting and nonlinear mixed-effects models were used.

RESULTS

When E2 was <5500 pg/mL, the CLBR increased by 10% for every 1000 pg/mL increase in E2. When E2 was between 5500 and 13 281 pg/mL, CLBR increased by 1.8% for every 1000 pg/mL increase in E2. When E2 was >13 281 pg/mL, CLBR decreased by 3% for every 1000 pg/mL increase in E2. From group E2 < 1000 to group E2 > 5000 pg/mL, pregnancy and live birth rates in fresh cycles were not related to E2. The live birth rate after FET was higher in the E2 ≥ 5000 pg/mL group than in the E2 < 1000 pg/mL group (odds ratio [OR] 4.03, and 95% confidence interval [CI] 3.74-4.35; adjusted OR 1.20, 95% CI 1.05-1.37).

CONCLUSION

CLBR is associated with E2 on trigger day in a segmented manner. Pregnancy and live birth rates in fresh cycles were not associated with E2. The live birth rate in FET cycles was highest when E2 ≥ 5000 pg/mL.

Effect of the ratios of estradiol increase on the outcome of in vitro fertilization-embryo transfer with antagonist regimens: a single center retrospective cohort study

BACKGROUND

The outcome of in vitro fertilization-embryo transfer (IVF) is often determined according to follicle and estradiol levels following gonadotropin stimulation. In previous studies, although most of them analyzed the estrogen level from ovaries or the average estrogen level of a single follicle, there was no study on the ratio of estrogen increase, which was also correlated with pregnancy outcomes in the clinic. This study aimed to make timely adjustments to follow-up medication to improve clinical outcomes based on the potential value of estradiol growth rate.

METHODS

We comprehensively analyzed estrogen growth during the entire ovarian stimulation period. Serum estradiol levels were measured on the day of gonadotropin treatment (Gn1), five days later (Gn5), eight days later (Gn8), and on the trigger day (HCG). This ratio was used to determine the increase in estradiol levels. According to the ratio of estradiol increase, the patients were divided into four groups: A1 (Gn5/Gn1 ≤ 6.44), A2 (6.44 < Gn5/Gn1 ≤ 10.62), A3 (10.62 < Gn5/Gn1 ≤ 21.33), and A4 (Gn5/Gn1 > 21.33); B1 (Gn8/Gn5 ≤ 2.39), B2 (2.39 < Gn8/Gn5 ≤ 3.03), B3 (3.03 < Gn8/Gn5 ≤ 3.84), and B4 (Gn8/Gn5 > 3.84). We analyzed and compared the relationship between data in each group and pregnancy outcomes.

RESULTS

In the statistical analysis, the estradiol levels of Gn5 (P = 0.029, P = 0.042), Gn8 (P < 0.001, P = 0.001), and HCG (P < 0.001, P = 0.002), as well as Gn5/Gn1 (P = 0.004, P = 0.006), Gn8/Gn5 (P = 0.001, P = 0.002), and HCG/Gn1 (P < 0.001, P < 0.001) both had clinical guiding significance, and lower one significantly reduced the pregnancy rate. The outcomes were positively linked to groups A (P = 0.036, P = 0.043) and B (P = 0.014, P = 0.013), respectively. The logistical regression analysis revealed that group A1 (OR = 0.376 [0.182-0.779]; P = 0.008*, OR = 0.401 [0.188-0.857]; P = 0.018*) and B1 (OR = 0.363 [0.179-0.735]; P = 0.005*, OR = 0.389 [0.187-0.808]; P = 0.011*) had opposite influence on outcomes.

CONCLUSION

Maintaining a serum estradiol increase ratio of at least 6.44 on Gn5/Gn1 and 2.39 on Gn8/Gn5 may result in a higher pregnancy rate, especially in young people.

A randomized double blind comparison of atosiban in patients with recurrent implantation failure undergoing IVF treatment

BACKGROUND

Patients with recurrent implantation failure (RIF) may have more uterine contractions. Several observational studies suggested that atosiban administration around embryo transfer resulted in higher pregnancy rates in RIF patients. This study aimed to evaluate the effect of atosiban given before fresh embryo transfer on pregnancy outcomes of women with RIF.

METHODS

A prospective, randomized, double-blind controlled clinical trial was performed in IVF center of Shanghai First Maternity and Infant Hospital. According to a computer-generated randomization list, 194 infertile women with RIF received fresh embryo transfer between July 2017 and December 2019 were randomly allocated into the atosiban (n = 97) and the placebo (n = 97) groups. Women in the treatment group received atosiban intravenously about 30 min before embryo transfer with a bolus dose of 6.75 mg over one minute. Those in the placebo group received only normal saline infusion for the same duration.

RESULTS

There was no significant difference in the live birth rate between the atosiban and placebo groups (42.3% vs 35.1%, P = 0.302, RR = 1.206 (0.844-1.723)). No significant differences were found between the two groups in the positive pregnancy test, clinical pregnancy, ongoing pregnancy, miscarriage, multiple pregnancy, ectopic pregnancy and implantation rates. Similar results were found when stratified by the number of embryos previously transferred, number of previous failed embryo transfers, frequency of endometrial peristalsis on embryo transfer day (≥ 3 waves/min) or serum estradiol (E₂) on the day of hCG above the median level. And, there was no correlation between the serum E₂ level on the day of hCG and the frequency of endometrial peristalsis on embryo transfer day. The frequency of endometrial peristalsis on embryo transfer day, total FSH/HMG dosage and duration were the significant factors which independently predicted the likelihood of a live birth.

CONCLUSIONS

These results suggested that atosiban treatment before fresh embryo transfer might not improve the live birth rate in RIF patients.

TRIAL REGISTRATION

The study had been approved by the Institutional Review Board of the hospital (2017 ethics No.43) and was registered under Clinicaltrials.gov with an identifier NCT02893722.

Dual trigger protocol is an effective in vitro fertilization strategy in both normal and high responders without compromising pregnancy outcomes in fresh cycles

Objective

To study the birth rates of normal vs. high responders after dual trigger of final oocyte maturation with gonadotropin-releasing hormone (GnRH) agonist and human chorionic gonadotropin in fresh in vitro fertilization (IVF) cycles in which ovarian stimulation was achieved by a flexible GnRH antagonist protocol.

Design

Retrospective cohort study.

Setting

University hospital.

Patient(s)

In women <35 years of age, 290 fresh IVF cycles using the dual trigger protocol with day 5 embryo transfers from January 2013 to July 2018 were included. Cycles excluded were those with preimplantation genetic testing, gestational carriers, donor oocytes, and fertility preservation.

Intervention(s)

IVF with dual trigger.

Main Outcome Measure(s)

Clinical pregnancy rate, live birth rate.

Result(s)

Comparing normal responders, defined as <30 oocytes retrieved, and high responders, defined as ≥30 oocytes retrieved, the clinical pregnancy rates (67.0% vs. 69.3%, respectively) and live birth rates (60.5% vs. 60.0%, respectively) were not significantly different. No cases of ovarian hyperstimulation syndrome were reported in either group.

Conclusion(s)

Ovarian stimulation by a flexible GnRH antagonist protocol followed by dual trigger yields comparable outcomes between normal and high responders in fresh IVF cycles.

Association between serum oestradiol level on the hCG administration day and neonatal birthweight after IVF-ET among 3659 singleton live births

Oestradiol, an important hormone in follicular development and endometrial receptivity, is closely related to clinical outcomes of fresh in vitro fertilization-embryo transfer (IVF-ET) cycles. A supraphysiologic E2 level is inevitable during controlled ovarian hyper-stimulation (COH), and its effect on the outcome of IVF-ET is controversial. The aim of this retrospective study is to evaluate the association between elevated serum oestradiol (E2) levels on the day of human chorionic gonadotrophin (hCG) administration and neonatal birthweight after IVF-ET cycles. The data of 3659 infertile patients with fresh IVF-ET cycles were analysed retrospectively between August 2009 and February 2017 in First Hospital of Zhengzhou University. Patients were categorized by serum E2 levels on the day of hCG administration into six groups: group 1 (serum E₂ levels ≤ 1000 pg/mL, n = 230), group 2 (serum E2 levels between 1001 and 2000 pg/mL, n = 524), group 3 (serum E₂ levels between 2001 and 3000 pg/mL, n = 783), group 4 (serum E₂ levels between 3001 and 4000 pg/mL, n = 721), group 5 (serum E2 levels between 4001 and 5000 pg/mL, n = 548 ), and group 6 (serum E2 levels > 5000 pg/mL, n = 852). Univariate linear regression was used to evaluate the independent correlation between each factor and outcome index. Multiple logistic regression was used to adjust for confounding factors. The LBW rates were as follows: 3.0% (group 1), 2.9% (group 2), 1.9% (group 3), 2.9% (group 4), 2.9% (group 5), and 2.0% (group 6) (P = 0.629), respectively. There were no statistically significant differences in the incidences of neonatal LBW among the six groups. We did not detect an association between peak serum E2 level during ovarian stimulation and neonatal birthweight after IVF-ET. The results of this retrospective cohort study showed that serum E2 peak levels during ovarian stimulation were not associated with birth weight during IVF cycles. In addition, no association was found between higher E2 levels and increased LBW risk. Our observations suggest that the hyper-oestrogenic milieu during COS does not seem to have adverse effects on the birthweight of offspring after IVF. Although this study provides some reference, the obstetric-related factors were not included due to historical reasons. The impact of the high estrogen environment during COS on the birth weight of IVF offspring still needs future research.

Does the elevated estradiol level on the day of human chorionic gonadotropin administration affect embryo quality among women undergoing in vitro fertilization?

OBJECTIVE

To evaluate the association between estradiol (E2 ) levels on the day of human chorionic gonadotropin (hCG) administration and embryo quality during in vitro fertilization (IVF) cycles.

METHODS

A retrospective study of 6676 IVF cycles among women treated at the Reproductive Center of The First Affiliated Hospital of USTC, Hefei, China, from June 2014 to May 2017. E2 levels on hCG day were divided into four groups by 25th percentile: 0-1763 pg/mL (group I), 1763-3692 pg/mL (group II), 3692-4800 pg/mL (group III), and higher than 4800 pg/mL (group IV). Analysis of variance and multiple linear regression were used to test associations.

RESULTS

There were significant differences in the frequency of high-quality embryos between group I (51.6 ± 1.1%) and groups II (65.6 ± 0.8%), III (62.1 ± 0.7%), and IV (62.3 ± 0.7%). Using E2 as a dummy variable and group II as a control, multiple linear regression showed that E2 levels were associated with the frequency of high-quality embryos obtained (P < 0.05).

CONCLUSION

Serum E2 on hCG day had an impact on embryo quality. Higher E2 levels did not produce the most high-quality embryos; the highest frequencies were achieved for E2 levels within 1763-3692 pg/mL.

Clinical and genetic analysis of cytochrome P450 oxidoreductase (POR) deficiency in a female and the analysis of a novel POR intron mutation causing alternative mRNA splicing : Overall analysis of a female with POR deficiency

OBJECTIVE

To characterize the clinical features of a female with P450 oxidoreductase (POR) deficiency and to investigate the underlying mechanisms of POR inactivation.

METHODS

The proband was a 35-year-old woman with primary infertility and menstrual irregularity. The reproductive endocrine profile was evaluated. DNA sequencing was conducted for the identification of POR gene mutation. RT-PCR was performed to confirm the impact of the mutation on POR mRNA. A molecular model was built for the structural analysis of mutant POR protein.

RESULTS

The evaluation of reproductive endocrine profile revealed elevation of serum follicle-stimulating hormone (11.48 mIU/ml), progesterone (11.00 ng/ml), 17α-hydroxyprogesterone (24.24 nmol/l), dehydroepiandrosterone (6300 nmol/l), and androstenedione (3.89 nmol/l) and decreased estradiol (36.02 pg/ml). Sequencing of the POR gene showed the female was a compound heterozygote of the paternal P399_E401 deletion and a novel maternal IVS14-1G>C mutation. Functional analysis revealed IVS14-1G>C mutation caused alternative splicing of POR mRNA, with the loss of 12 nucleotides in exon 15 (c.1898_1909delGTCTACGTCCAG). Also, the resulting mutant POR protein had a V603_Q606 deletion, which inactivated the nucleotide-binding domain of NADPH in POR protein (K602_Q606).

CONCLUSION

The mutation IVS14-1G>C of the POR gene could cause alternative splicing of POR mRNA and dysfunction of the resulting POR protein. Under proper IVF strategy with glucocorticoid therapy and endometrial preparation, females with mild POR deficiency still have the opportunity to have a live birth.

Is the probability of pregnancy after ovarian stimulation for IVF associated with serum estradiol levels on the day of triggering final oocyte maturation with hCG? A systematic review and meta-analysis

PURPOSE

The objective of this systematic review and metaanalysis was to examine if the probability of pregnancy after ovarian stimulation for in vitro fertilization (IVF), using GnRH analogues and gonadotrophins is associated with serum estradiol level (Ε₂) on the day of triggering final oocyte maturation with human chorionic gonadotrophin (hCG).

METHODS

Twenty-one studies were eligible for this systematic review, including 19,598 IVF cycles, whereas three studies were eligible for metaanalysis, including 641 IVF cycles. The main outcome measure was achievement of ongoing pregnancy/live birth and, if not available, clinical pregnancy or biochemical pregnancy.

RESULTS

Pooling of data showed no differences in the probability of clinical pregnancy between patients with high and low Ε₂ levels on the day of triggering final oocyte maturation. The pooled effect sizes for the Ε₂ thresholds groups constructed, regarding clinical pregnancy were 2000-3000 pg/mL-OR 0.91, 95% CI 0.55 to 1.50, (fair quality/moderate risk of bias, n = 1 study), 3000-4000 pg/mL-OR 0.89, 95% CI 0.46 to 1.70, (fair quality/moderate risk of bias, n = 1 study, good quality/no information on which to base a judgement about risk of bias n = 2 studies), 4000-5000 pg/mL-OR 0.74, 95% CI 0.37 to 1.49 fair quality/moderate risk of bias, n = 1 study), 5000-6000 pg/mL-OR 0.62, 95% CI 0.19 to 1.98, (fair quality/moderate risk of bias, n = 1 study). In addition, no difference was observed in the probability of ongoing pregnancy for the Ε₂ threshold group of 3000-4000 pg/mL OR 0.85, 95% CI 0.40 to 1.81(good quality/no information on which to base a judgement about risk of bias, n = 1 study).

CONCLUSION

Currently, there is insufficient evidence to support or deny the presence of an association between the probability of pregnancy and serum Ε₂ levels on the day of triggering final oocyte maturation with hCG in women undergoing ovarian stimulation for IVF.

A mediation analysis for a nonrare dichotomous outcome with sequentially ordered multiple mediators

Mediation analyses can help us to understand the biological mechanism in which an exposure or treatment affects an outcome. Single mediator analyses have been used in various applications, but may not be appropriate for analyzing intricate mechanisms involving multiple mediators that affect each other. Thus, in this article, we studied multiple sequentially ordered mediators for a dichotomous outcome and presented the identifiability assumptions for the path-specific effects on the outcome, that is, the effect of an exposure on the outcome mediated by a specific set of mediators. We proposed a closed-form estimator for the path-specific effects by modeling the dichotomous outcome using a probit model. Asymptotic variance of the proposed estimator is derived and can be approximated via delta method or bootstrapping. Simulations under a finite sample showed the validity of our method in capturing the path-specific effects when the probability of each potential counterfactual outcome is not small and demonstrated the utility of a computationally efficient alternative to bootstrapping for calculating variance. The method is applied to investigate the effects of polycystic ovarian syndrome on live birth rates mediated by estradiol levels and the number of oocytes retrieved in a large electronic in vitro fertilization database. We implemented the method into an R package SOMM, which is available at https://github.com/roqe/SOMM.

Association between serum estradiol level on the human chorionic gonadotrophin administration day and clinical outcome

BACKGROUND

Estradiol, as an important hormone in follicular development and endometrial receptivity, is closely related to clinical outcomes of fresh in vitro fertilization embryo transfer (IVF-ET) cycles. The aim of this retrospective study was to evaluate the association between elevated serum estradiol (E2) levels on the day of human chorionic gonadotrophin (hCG) administration and IVF-ET pregnancy and birth outcomes.

METHODS

A total of 1771 infertile patients with their first fresh IVF-ET cycles were analyzed retrospectively between January 2011 and January 2016 in Peking University First Hospital. Patients were categorized by serum E2 levels on the day of hCG administration into six groups: group 1 (serum E2 levels ≤ 1000 pg/mL, n = 205), group 2 (serum E2 levels 1001-2000 pg/mL, n = 457), group 3 (serum E2 levels 2001-3000 pg/mL, n = 425), group 4 (serum E2 levels 3001-4000 pg/mL, n = 310), group 5 (serum E2 levels 4001-5000 pg/mL, n = 237), and group 6 (serum E2 levels > 5000 pg/mL, n = 137). The retrieved oocyte and MII oocyte numbers and implantation and clinical pregnancy rates of the groups were compared as the first objective of the study. For the 360 women with singleton births among all patients, the area under the corresponding receiver operating characteristic curve (ROC curve) was calculated to assess the predictive value of the E2 change for the probability of low birth weight (LBW) infants as the second objective.

RESULTS

The retrieved oocyte and MII oocyte numbers and implantation and clinical pregnancy rates gradually increased from groups 1 to 5 but decreased in group 6. The parameters of group 1 were statistically worse than those of the other groups, from group 2 to group 6 (the number of retrieved oocytes, t = 13.096, t = 23.307, t = 23.086, t = 26.376, t = 19.636, P < 0.003; the number of retrieved MII oocytes, t = 10.856, t = 20.868, t = 21.874, t = 23.374, t = 19.092, P < 0.003; the implantation rate, χ = 12.179, χ = 22.239, χ = 23.993, χ = 23.344, χ = 16.758, P < 0.003; the clinical pregnancy rate, χ = 16.415, χ = 28.074, χ = 35.387, χ = 37.025, χ = 24.590, P < 0.003). ROC analysis revealed that when a serum peak E2 of 3148 pg/mL was used to predict LBW.

CONCLUSIONS

The results indicate that serum E2 levels have a concentration-dependent effect on clinical outcomes. The optimal range of the E2 level during a fresh IVF-ET cycle is 1000 to 3148 pg/mL.

Pregnancy And Neonatal Outcomes Of hMG Stimulation With Or Without Letrozole In Endometrial Preparation For Frozen-Thawed Embryo Transfer In Ovulatory Women: A Large Retrospective Cohort Study

Objective

Frozen–thawed embryo transfer enables surplus embryos derived from IVF or IVF-ICSI treatment to be stored and transferred in subsequent cycles into a more “physiologic environment”. This study aimed to investigate the clinical effect of letrozole use or hMG stimulation on pregnancy and neonatal outcomes in ovulatory patients undergoing FET.

Methods

This study includes a total of 5901 FET cycles with letrozole use (n = 1569), HMG (n =1827) or letrozole + HMG (n = 2505). In the letrozole group, 2.5 mg of letrozole was administered on menstrual cycle day 3 to 5 for 3 days for patients, and then follicle growth was monitored beginning on day 10. If the follicular diameter was ≥14 mm on the 10th day, no other ovarian stimulation drugs were needed. If the follicular diameter was <14 mm on the 10th day, 150 IU human menopausal gonadotropin (hMG) was added to stimulate follicle growth every two days (hMG + letrozole group). In hMG stimulation group, a total of 150 IU of hMG was injected every two days to stimulate development of follicles from cycle day 10 to 12.

Results

Compared with the patients undergoing hMG stimulation, the group receiving letrozole or letrozole+HMG stimulation exhibits significantly higher clinical pregnancy rates per transfer (hMG: 47.02% vs letrozole: 52.07% vs letrozole+HMG: 52.26%) and implantation rates (hMG: 31.76% vs letrozole: 34.36% vs letrozole+HMG: 34.24%). In addition, the letrozole group was associated with a statistically significantly lower incidence of miscarriage (hMG: 14.78% vs letrozole: 10.53% vs letrozole+HMG: 14.13%) and ectopic pregnancies (hMG: 1.83% vs letrozole: 0.97% vs letrozole+HMG: 1.58%) than the letrozole + HMG and HMG groups. Neonatal outcomes are similar among the three groups.

Conclusion

Our data demonstrate that the letrozole use may improve clinical pregnancy outcomes and decrease the risk of ectopic pregnancies and miscarriage in ovulatory patients who receive FET cycles.

Ovarian manipulation in ART: going beyond physiological standards to provide best clinical outcomes

Current knowledge on ovarian physiology has challenged the traditional concept of folliculogenesis, creating the basis for novel ovarian stimulation protocols in assisted reproduction technology. The purpose of this review was to evaluate the efficacy of novel clinical interventions that could aid clinicians in individualizing their protocols to patients' characteristics and personal situations. We conducted a literature review of the available evidence on new approaches for ovarian stimulation from both retrospective and prospective studies in the PubMed database. Here, we present some of the most important interventions, including follicle growth in the gonadotropin-independent and dependent stage, manipulation of estradiol production throughout ovarian stimulation, control of mid-cycle gonadotropin surges, and luteal phase support after different stimulation protocols and trigger agents. The latest research on IVF has moved physicians away from the classical physiology, allowing the development of new strategies to decouple organ functions from the female reproductive system and challenging the traditional concept of IVF.

Effect of elevated estradiol levels on the hCG administration day on IVF pregnancy and birth outcomes in the long GnRH-agonist protocol: analysis of 3393 cycles

INTRODUCTION

This retrospective study aimed to evaluate the association between elevated serum estradiol (E ₂) levels on the human chorionic gonadotrophin (hCG) administration day and in vitro fertilization (IVF) pregnancy and birth outcomes in the long GnRH-agonist protocol.

METHODS

This study analyzed the data of 3393 infertile women who underwent initial fresh IVF. The patients were categorized into high and low E ₂ groups based on their serum E ₂ levels on the hCG day. Pregnancy and birth outcomes were compared.

RESULTS

The implantation rate, clinical pregnancy rate, and live birth rate were all significantly higher in the high E ₂ group than in the low E ₂ group (p < 0.05). The good-quality embryo rate and abortion rate did not significantly differ between the two groups. There were no significant differences in the mode of delivery, gestational age, birth weight, and fetal gender between the two groups. Furthermore, there were no differences in the risk of preterm birth, low birth weight, and fetal malformation between the two groups in 860 single live births. Subgroup analysis of singleton pregnancies in the high E ₂ (E ₂ ≥ 3757 pg/mL) group revealed a significant increase in abortion rate in the age group of ≥37 years.

CONCLUSIONS

Elevated serum E ₂ levels associated with controlled ovarian stimulation did not increase the risks of preterm birth, low birth weight, and fetal malformation. High E ₂ on the hCG day had no detrimental effect on the implantation rate, clinical pregnancy rate, and live birth rate.