Comparison of daily vaginal progesterone gel plus weekly intramuscular progesterone with daily intramuscular progesterone for luteal phase support in single, autologous euploid frozen-thawed embryo transfers

Opening the black box: why do euploid blastocysts fail to implant? A systematic review and meta-analysis

BACKGROUND

A normal chromosomal constitution defined through PGT-A assessing all chromosomes on trophectoderm (TE) biopsies represents the strongest predictor of embryo implantation. Yet, its positive predictive value is not higher than 50-60%. This gap of knowledge on the causes of euploid blastocysts' reproductive failure is known as 'the black box of implantation'.

OBJECTIVE AND RATIONALE

Several embryonic, maternal, paternal, clinical, and IVF laboratory features were scrutinized for their putative association with reproductive success or implantation failure of euploid blastocysts.

SEARCH METHODS

A systematic bibliographical search was conducted without temporal limits up to August 2021. The keywords were '(blastocyst OR day5 embryo OR day6 embryo OR day7 embryo) AND (euploid OR chromosomally normal OR preimplantation genetic testing) AND (implantation OR implantation failure OR miscarriage OR abortion OR live birth OR biochemical pregnancy OR recurrent implantation failure)'. Overall, 1608 items were identified and screened. We included all prospective or retrospective clinical studies and randomized-controlled-trials (RCTs) that assessed any feature associated with live-birth rates (LBR) and/or miscarriage rates (MR) among non-mosaic euploid blastocyst transfer after TE biopsy and PGT-A. In total, 41 reviews and 372 papers were selected, clustered according to a common focus, and thoroughly reviewed. The PRISMA guideline was followed, the PICO model was adopted, and ROBINS-I and ROB 2.0 scoring were used to assess putative bias. Bias across studies regarding the LBR was also assessed using visual inspection of funnel plots and the trim and fill method. Categorical data were combined with a pooled-OR. The random-effect model was used to conduct the meta-analysis. Between-study heterogeneity was addressed using I2. Whenever not suitable for the meta-analysis, the included studies were simply described for their results. The study protocol was registered at http://www.crd.york.ac.uk/PROSPERO/ (registration number CRD42021275329).

OUTCOMES

We included 372 original papers (335 retrospective studies, 30 prospective studies and 7 RCTs) and 41 reviews. However, most of the studies were retrospective, or characterized by small sample sizes, thus prone to bias, which reduces the quality of the evidence to low or very low. Reduced inner cell mass (7 studies, OR: 0.37, 95% CI: 0.27-0.52, I2 = 53%), or TE quality (9 studies, OR: 0.53, 95% CI: 0.43-0.67, I2 = 70%), overall blastocyst quality worse than Gardner's BB-grade (8 studies, OR: 0.40, 95% CI: 0.24-0.67, I2 = 83%), developmental delay (18 studies, OR: 0.56, 95% CI: 0.49-0.63, I2 = 47%), and (by qualitative analysis) some morphodynamic abnormalities pinpointed through time-lapse microscopy (abnormal cleavage patterns, spontaneous blastocyst collapse, longer time of morula formation I, time of blastulation (tB), and duration of blastulation) were all associated with poorer reproductive outcomes. Slightly lower LBR, even in the context of PGT-A, was reported among women ≥38 years (7 studies, OR: 0.87, 95% CI: 0.75-1.00, I2 = 31%), while obesity was associated with both lower LBR (2 studies, OR: 0.66, 95% CI: 0.55-0.79, I2 = 0%) and higher MR (2 studies, OR: 1.8, 95% CI: 1.08-2.99, I2 = 52%). The experience of previous repeated implantation failures (RIF) was also associated with lower LBR (3 studies, OR: 0.72, 95% CI: 0.55-0.93, I2 = 0%). By qualitative analysis, among hormonal assessments, only abnormal progesterone levels prior to transfer were associated with LBR and MR after PGT-A. Among the clinical protocols used, vitrified-warmed embryo transfer was more effective than fresh transfer (2 studies, OR: 1.56, 95% CI: 1.05-2.33, I2 = 23%) after PGT-A. Lastly, multiple vitrification-warming cycles (2 studies, OR: 0.41, 95% CI: 0.22-0.77, I2 = 50%) or (by qualitative analysis) a high number of cells biopsied may slightly reduce the LBR, while simultaneous zona-pellucida opening and TE biopsy allowed better results than the Day 3 hatching-based protocol (3 studies, OR: 1.41, 95% CI: 1.18-1.69, I2 = 0%).

WIDER IMPLICATIONS

Embryo selection aims at shortening the time-to-pregnancy, while minimizing the reproductive risks. Knowing which features are associated with the reproductive competence of euploid blastocysts is therefore critical to define, implement, and validate safer and more efficient clinical workflows. Future research should be directed towards: (i) systematic investigations of the mechanisms involved in reproductive aging beyond de novo chromosomal abnormalities, and how lifestyle and nutrition may accelerate or exacerbate their consequences; (ii) improved evaluation of the uterine and blastocyst-endometrial dialogue, both of which represent black boxes themselves; (iii) standardization/automation of embryo assessment and IVF protocols; (iv) additional invasive or preferably non-invasive tools for embryo selection. Only by filling these gaps we may finally crack the riddle behind 'the black box of implantation'.

The optimal route of progesterone administration for luteal phase support in a frozen embryo transfer: a systematic review

OBJECTIVE

To investigate the optimal route of progesterone administration for luteal phase support in a frozen embryo transfer.

DESIGN

Systematic review.

PATIENTS

Women undergoing frozen embryo transfer (FET).

INTERVENTIONS

We conducted an extensive database search of Medline (PubMed), Embase, Web of Science, and Cochrane Trials Register using relevant keywords and their combinations to find randomized controlled trials (RCTs) comparing the routes (i.e., oral, vaginal, intramuscular) of progesterone administration for luteal phase support (LPS) in artificial FET.

MAIN OUTCOME MEASURES

Clinical pregnancy, live birth, miscarriage.

RESULTS

Four RCTs with 3245 participants undergoing artificial endometrial preparation (EP) cycles during FET were found to be eligible. Four trials compared vaginal progesterone with intramuscular progesterone and two trials compared vaginal progesterone with oral progesterone. One study favored of vaginal versus oral progesterone for clinical pregnancy rates (RR 0.45, 95% CI 0.22-0.92) and other study favored intramuscular versus vaginal progesterone for clinical pregnancy rates (RR 1.46, 95% CI 1.21-1.76) and live birth rates (RR 1.62, 95% CI 1.28-2.05). Tabulation of overall evidence strength assessment showed low-quality evidence on the basis that for each outcome-comparison pair, there were deficiencies in either directness of outcome measurement or study quality.

CONCLUSION

There was little consensus and evidence was heterogeneous on the optimal route of administration of progesterone for LPS during FET in artificial EP cycles. This warrants more trials, indirect comparisons, and network meta-analyses.

PROPERO NO

CRD42021251017.

Serum progesterone level in luteal phase improves pregnancy rate in fresh cycles with blastocyst embryo transfer

OBJECTIVE

To assess the association between serum level of progesterone during stimulation and in the luteal phase with pregnancy rate in a cohort of patients undergoing in vitro fertilization and embryo transfer (IVF-ET) on day 5.

METHODS

Retrospective Cohort Study. Patients: 62 infertile women, aged 24-42 years, undergoing ART at our center from May 2019 to May 2021. Progesterone was evaluated during ovarian stimulation on Day 2, Day 6, and Day 8 of stimulation, day of trigger (P4dhCG), and on the day of blastocyst transfer with 5 days of progesterone supplementation (P4d5+). We also calculated the difference of P4d5+ with P4dhCG. (∆P4). Then we divided the patients into two groups based on progesterone serum levels at P4d5+; <10ng/ml (Group A), ≥10ng/ml (Group B). The Student's t-test was performed for continuous variables; Mann-Whitney's Test and Spearman's Test were used where appropriate for categorical variables. p<0.05 was considered statistically significant.

RESULTS

There were positive correlations between βhCG positive with P4d5+ (p<0.001; Rho 0.770) and ∆P4 (p<0.001; Rho 0.703). The pregnancy rate doubled when the serum progesterone level was ≥10ng/ml on the fifth day of progesterone supplementation compared with P4<10ng/ml (44% vs. 21%, respectively).

CONCLUSIONS

The pregnancy rate was positively correlated with the serum P4 level on the fifth day of progesterone supplementation and with the difference between the serum progesterone level in the Dd5+ / dhCG. A higher pregnancy rate was observed when serum progesterone level on the fifth day of progesterone supplementation was ≥10ng/ml.

Does endometrial thickness affect birth weight and serum levels of pregnancy-associated plasma protein-A in frozen cycles?

OBJECTIVE

To investigate whether endometrial thickness (EMT) affects birth weight and maternal serum pregnancy-associated plasma protein-A (PAPP-A) level in singleton pregnancies following frozen-thawed blastocyst transfer (FET).

METHODS

This retrospective study included women who underwent first-trimester combined screening for aneuploidy after FET, and subsequently delivered a singleton live birth after 24 weeks of gestation at a private in-vitro fertilization centre. The subjects were stratified into three groups based on EMT percentiles: <7.7 mm (<10th percentile), 7.7-12 mm (10-90th percentile), and > 12 mm (>90th percentile). Multi-variable linear regression analysis was undertaken to identify the association between birth weight and EMT after adjusting for variables with p < 0.1 on univariate analysis.

RESULTS

In total, 560 women met the inclusion criteria. Mean (±standard deviation) birth weight was 3127 ± 783 g in those with EMT < 7.7 mm, 3225 ± 644 g in those with EMT 7.7-12 mm, and 3256 ± 599 g in those with EMT > 12 mm (p = 0.577). Mean PAPP-A and PAPP-A < 0.5 rates were similar in the three groups. On multi-variate analysis, maternal serum PAPP-A was found to be a significant predictor of birth weight (p = 0.013), but EMT was not found to be predictive of birth weight on univariate or multi-variate analysis.

CONCLUSION

This study provided a new angle to evaluate the association between EMT and neonatal birth weight by analysing this association along with maternal serum PAPP-A as a marker for placental function, suggesting that EMT is not an independent factor for neonatal birth weight.

Pharmacokinetics, safety and bioequivalence of two formulations of progesterone soft capsule in healthy Chinese postmenopausal females: Impacts of a high-fat meal

Progesterone is an important natural hormone regulating ovulation and menstruation. The present study aimed to investigate the pharmacokinetics and safety of two formulations of progesterone in Chinese postmenopausal females under fasting and fed conditions. The study adopted a single-dose, open-label, randomized, three-period bioequivalence design. A total of 96 subjects were enrolled and randomly assigned to the fasting cohort or fed cohort. A high-fat meal (890 kcal) was used in the fed study. The reference-scaled average bioequivalence method was used for bioequivalence evaluation. A high-fat meal led to a 22-fold higher peak concentration (C_max ) and a 7-fold higher area under the curve (AUC) while time to reach C_max and half-life was not significantly affected. The concentration-time curve displayed double peaks suggesting the existence of enterohepatic circulation. The test/reference geometric mean ratios for C_max and AUC under fasting and fed conditions are all within the range of 80% to 125%. All adverse events (AEs) that occurred during the trial were mild and did not cause drop-out, though these AEs occurred more frequently under fed state. In conclusion, the two formulations of progesterone are bioequivalent in Chinese subjects under fasting and fed conditions. Drug label modification regarding food effects needs further discussion.

Serum luteal phase progesterone in women undergoing frozen embryo transfer in assisted conception: a systematic review and meta-analysis

OBJECTIVE

To investigate the association between luteal serum progesterone levels and frozen embryo transfer (FET) outcomes.

DESIGN

Systematic review and meta-analysis.

SETTING

Not applicable.

PATIENT(S)

Women undergoing FET.

INTERVENTION(S)

We conducted electronic searches of MEDLINE, PubMed, CINAHL, EMBASE, the Cochrane Database of Systematic Reviews, Cochrane Central Register of Controlled Trials, Web of Science, ClinicalTrials.gov, and grey literature (not widely available) from inception to March 2021 to identify cohort studies in which the serum luteal progesterone level was measured around the time of FET.

MAIN OUTCOME MEASURE(S)

Ongoing pregnancy or live birth rate, clinical pregnancy rate, and miscarriage rate.

RESULT(S)

Among the studies analyzing serum progesterone level thresholds <10 ng/mL, a higher serum progesterone level was associated with increased rates of ongoing pregnancy or live birth (relative risk [RR] 1.47, 95% confidence interval [CI] 1.28 to 1.70), higher chance of clinical pregnancy (RR 1.31, 95% CI 1.16 to 1.49), and lower risk of miscarriage (RR 0.62, 95% CI 0.50 to 0.77) in cycles using exclusively vaginal progesterone and blastocyst embryos. There was uncertainty about whether progesterone thresholds ≥10 ng/mL were associated with FET outcomes in sensitivity analyses including all studies, owing to high interstudy heterogeneity and wide CIs.

CONCLUSION(S)

Our findings indicate that there may be a minimum clinically important luteal serum concentration of progesterone required to ensure an optimal endocrine milieu during embryo implantation and early pregnancy after FET treatment. Future clinical trials are required to assess whether administering higher-dose luteal phase support improves outcomes in women with a low serum progesterone level at the time of FET.

PROSPERO NUMBER

CRD42019157071.

Investigating the impact of different strategies for endometrial preparation in frozen cycles considering normal responders undergoing IVF/ICSI cycles: a multicenter retrospective cohort study

Uncertainty exists concerning the type, adjunct, or dose of regimen to offer in frozen cycles in infertile women undergoing IVF/ICSI. Current systematic reviews have failed to identify one method of endometrial preparation as being more effective than another, whereas many IVF Units use variable and mixed protocols mainly based on their experience and convenience of use. Thus, we performed a four-center two-arm retrospective cohort study, encompassing 439 cycles in 311 women. The modalities analyzed were: Modified natural cycle without and with luteal support (Groups 1,2) and Hormone Replacement cycle (HRC) with and without GnRHa suppression (Groups 3,4). Various schemes of progesterone and estradiol were used and compared. χ² tests for categorical data and t-tests for continuous data were employed, stratifying by exposure, along with univariate and multivariable Logistic Regression models and subgroup analyses, according to the number of embryos transferred (1 vs. ≥2) and day of transfer (d2 vs. d5). Group 3 presented with statistically significant higher live birth and miscarriage rates in comparison to Group 4 (RR = 5.87, 95%CI: 2.44-14.14 and RR = 0.19, 95%CI: 0.06-0.60, respectively), findings that persisted in subgroup analyses according to the day of transfer and the number of embryos transferred. Progesterone administration through the combination of vaginal tabs and gel was associated with lower clinical pregnancy rates when compared to tabs (RR = 0.19, 95%CI: 0.05-0.71). The stable estrogen protocol compared to increasing estrogen at day 5 was associated with a higher positive hCG test and clinical pregnancy rate, while the progesterone through vaginal tabs was linked with lower miscarriages compared either with gel or combinations. In conclusion, HRC with GnRHa appears to be superior to HRC without GnRHa, concerning live birth and miscarriage, especially when the number of embryos transferred are ≥2 and irrespective of day of transfer. The use of progesterone vaginal tabs compared to gel or combinations is associated with better outcomes. Age is a significant predictor of a negative hCG test and clinical pregnancy rates. A properly conducted RCT is needed to evaluate the optimal frozen embryo transfer preparation strategy.Abbreviations: SD: standard deviation; BMI: body mass index; PCOS: polycystic ovarian syndrome; IQR: interquartile range; FSH: follicle-stimulating hormone; LH: luteinizing hormone; TSH: thyroid-stimulating hormone.

What is the optimal luteal support in assisted reproductive technology?

The need for luteal phase support in IVF/ICSI is well established. A large effort has been made in the attempt to identify the optimal type, start, route, dosage and duration of luteal phase support for IVF/ICSI and frozen embryo transfer. These questions are further complicated by the different types of stimulation protocols and ovulation triggers used in ART. The aim of this review is to supply a comprehensive overview of the available types of luteal phase support, and the indications for their use.A review of the literature was carried out in the effort to find the optimal luteal phase support regimen with regards to pregnancy related outcomes and short and long term safety.The results demonstrate that vaginal, intramuscular, subcutaneous and rectal progesterone are equally effective as luteal phase support in IVF/ICSI. GnRH agonists and oral dydrogesterone are new and promising treatment modalities but more research is needed. hCG and estradiol are not recommended for luteal phase support. More research is needed to establish the most optimal luteal phase support in frozen embryo transfer cycles, but progesterone has been shown to improve live birth rate in some studies. Luteal phase support should be commenced between the evening of the day of oocyte retrieval, and day three after oocyte retrieval and it should be continued at least until the day of positive pregnancy test.So, in conclusion still more large and well-designed RCT's are needed to establish the most optimal luteal phase support in each stimulation protocol, and especially in frozen embryo transfer.

Impact of Isthmocele on Assisted Reproductive Treatment Outcomes: An Age-matched Retrospective Study

STUDY OBJECTIVE

To evaluate whether the presence of an ultrasonographic visible isthmocele has an impact on the chance of pregnancy in women undergoing embryo transfer.

DESIGN

Age-matched retrospective study.

SETTING

Private-assisted reproductive center.

PATIENTS

The study included a total of 150 patients with a history of cesarean delivery with 75 isthmocele cases and 75 controls. All patients underwent embryo transfer from January 2017 through June 2018. The diagnosis of isthmocele was based on transvaginal ultrasound assessment. Isthmocele was defined as an anechoic indentation on the previous cesarean scar at the midsagittal plane, with a depth of >1 mm.

INTERVENTIONS

Embryo transfer.

MEASUREMENTS AND MAIN RESULTS

The groups were similar in patient and treatment characteristics. The live birth rate was 44% in the isthmocele group and 46.7% in the control group (odds ratio [OR] 0.89; 95% confidence interval [CI], 0.47-1.71; p = .743). The clinical pregnancy rates were 49.3% and 50.7%, respectively (OR, 0.94; 95% CI, 0.50-1.79; p = .870). The miscarriage rate was greater in the isthmocele group (8%) than in the control group (4%); however, it did not reach statistical significance (OR, 2.09; 95% CI, 0.50-8.67; p = .302). The multiple pregnancy rate was similar between the groups (8% vs 5.3%, respectively; OR, 1.54; 95% CI, 0.41-5.70; p = .513). The groups were also similar in ectopic pregnancy rates (p = .560). These outcomes remained similar when adjusted for potential confounders on the regression analysis.

CONCLUSION

Isthmocele does not seem to have a significant impact on the chance of pregnancy in assisted reproductive treatment settings. However, the embryo transfer procedure may be more difficult in the presence of an isthmocele.

Frozen blastocyst transfer improves the chance of live birth in women with endometrioma

Purpose: The existing literature is scarce regarding outcomes of fresh vs frozen embryo blastocyst transfers in women with endometrioma. The goal of the study was to compare outcomes between fresh and frozen blastocyst transfers (fresh-BT vs. frozen-BT) in endometrioma-affected women. Materials and methods: This study included 315 endometrioma-affected women aged between 20 and 39 years who underwent blastocyst transfer. Primary outcome was live birth rate (an alive birth after 24 completed weeks gestation). Results: The study groups did not differ in terms of patient characteristics and treatment variables. The live birth rate was 40.7% in fresh-BT group and 56.1% in frozen-BT group (OR:1.86, 95% CI:1.18-2.92 p = .007). The approach of frozen embryo transfer was an independent factor of live birth (adjusted OR:1.83, 95% CI:1.16-2.90, p = .009). Conclusion: The approach of frozen blastocyst transfer increases the chance of live birth in endometrioma-affected patients compared with fresh blastocyst transfer. Thus, a frozen embryo transfer may be the choice of strategy in these patients.

Preimplantation genetic testing for aneuploidy in severe male factor infertility

RESEARCH QUESTION

Does the use of preimplantation genetic testing for aneuploidies (PGT-A) improve outcomes in couples with severe male factor infertility (SMFI)?

DESIGN

This retrospective cohort study included SMFI cases that underwent blastocyst transfer with/without PGT-A. Inclusion criteria were SMFI (azoospermia and sperm count <1 million/ml), women aged 25-39 years, single vitrified-warmed blastocyst transfer, and no intracavitary pathologies. Patients were divided into PGT-A and non-PGT-A groups. The primary outcome was live birth rate (live birth of an infant after 24 weeks of gestation); secondary outcomes were implantation and clinical pregnancy rates.

RESULTS

The study included 266 SMFI cases (90 and 176 in the PGT-A and non-PGT-A groups, respectively). Men and women in the PGT-A group were significantly older than those in the non-PGT-A group. The groups did not differ in terms of male factor categories, sperm collection methods or additional female factors. Live birth rates in the PGT-A and non-PGT-A groups were 55.6% and 51.1%, respectively (odds ratio [OR] 1.19, 95% confidence interval [CI] 0.71-1.98, P = 0.495). The implantation rates were 65.6% and 64.2%, respectively (OR 1.06, 95% CI 0.62-1.80, P = 0.827). The clinical pregnancy rates were 62.2% and 58.0%, respectively (OR 1.19, 95% CI 0.71-2.01, P = 0.502). The use of PGT-A was not an independent factor for live birth (aOR 1.33, 95% CI 0.66-2.70, P = 0.421). Advanced age in women was the only independent factor associated with live birth (aOR 0.46, 95% CI 0.22-0.96, P = 0.041).

CONCLUSIONS

The use of PGT-A does not seem to be an independent factor associated with live birth per transfer in couples with SMFI.

Factors associated with serum progesterone concentrations the day before cryopreserved embryo transfer in artificial cycles

RESEARCH QUESTION

What factors determine serum progesterone concentrations the day before cryopreserved embryo transfer in artificially prepared cycles?

DESIGN

Retrospective cohort study at a university-affiliated fertility centre including infertile women under 45 years old using own oocytes who underwent a total of 685 single cryopreserved blastocyst transfers under hormonal therapy. Determinants that affected live birth rate (LBR) were analysed using a multivariate logistic regression. Univariate analysis and multivariate linear regression were used to evaluate independent factors that affect serum progesterone concentrations.

RESULTS

Age (odds ratio [OR] 0.93; 95% confidence interval [CI] 0.89-0.96), duration of oestradiol (OR 0.96; 95% CI 0.92-0.99), serum progesterone concentrations (OR 1.04; 95% CI 1.01-1.08) and patients who underwent preimplantation genetic testing for aneuploidies (PGT-A) (OR 2.17; 95% CI 1.55-3.03) were independently associated with LBR. After univariate analysis, determinants of progesterone concentrations were: age, weight, history of a previous cryopreserved embryo transfer with serum progesterone concentrations <10 ng/ml, and time of blood extraction. The multivariate linear regression showed that increasing age presented a positive correlation with progesterone concentrations (β = 0.11; 95% CI 0.01-0.20). On the contrary, significant negative correlations with progesterone concentrations were shown for a previous history of serum progesterone value <10 ng/ml (β = -3.13; 95% CI -4.45 to -1.81]), higher weight (β = -0.05; 95% CI -0.08 to -0.01) and the time of blood sampling during the day (β = -0.13; 95% CI -0.25 to -0.01).

CONCLUSIONS

This study adds more evidence regarding the importance of serum progesterone concentrations before frozen embryo transfer (FET). It also showed that body weight, age, time of blood sampling and a history of low progesterone are determinants associated with progesterone concentrations before blastocyst FET.