Best practice recommendations for medically assisted reproduction in patients with known cardiovascular disease or at high risk of cardiovascular disease

Increasing numbers of people are seeking assisted conception. In people with known cardiac disease or risk factors for cardiac disease, assisted conception may carry increased risks during treatment and any subsequent pregnancy. These risks should be assessed, considered and minimized prior to treatment.

Progesterone concentrations on blastocyst transfer day in modified natural cycle frozen embryo transfer cycles

RESEARCH QUESTION

Are serum progesterone concentrations on the day of modified natural cycle (mNC) frozen blastocyst transfer (FET) without luteal phase support (LPS) associated with clinical pregnancy rate (CPR)?

DESIGN

Data were collected between January 2019 and October 2022 as a sub-study of an ongoing randomized controlled trial assessing pregnancy outcomes in mNC-FET. The sub-study included all women (n = 209) randomized to mNC-FET without LPS at the time of data extraction. Participants were aged 18-41 years, had regular menstrual cycles and underwent mNC-FET treatment with single-blastocyst transfer. Associations between the serum progesterone concentration on the day of blastocyst transfer and CPR, pregnancy rate and pregnancy loss rate (PLR) were examined between groups with low and higher progesterone concentrations using the 25th and 10th percentiles as cut-offs. Multivariate logistic regression analyses were performed to adjust for potential confounding factors.

RESULTS

Progesterone concentrations on the day of blastocyst transfer in mNC-FET without LPS ranged from 4.9 to 91.8 nmol/l, with the 25th and 10th percentiles at 29.0 nmol/l and 22.5 nmol/l, respectively. Serum progesterone concentrations did not differ between women with or without a clinical pregnancy (mean [SD] 38.5 [14.0] versus 36.8 [12.4] nmol/l; P = 0.350). Furthermore, the CPR, pregancy rate and PLR were similar in women with low or high progesterone concentrations when using the 25th or the 10th progesterone percentile as cut-off. Multivariate regression analyses showed no association between progesterone concentrations and CPR.

CONCLUSIONS

No association was found between progesterone concentration on the day of blastocyst transfer and pregnancy outcome in women undergoing mNC-FET without progesterone LPS.

Management of hypertensive disorders in pregnancy: a Position Statement of the European Society of Hypertension Working Group 'Hypertension in Women'

Hypertensive disorders in pregnancy (HDP), remain the leading cause of adverse maternal, fetal, and neonatal outcomes. Epidemiological factors, comorbidities, assisted reproduction techniques, placental disorders, and genetic predisposition determine the burden of the disease. The pathophysiological substrate and the clinical presentation of HDP are multifarious. The latter and the lack of well designed clinical trials in the field explain the absence of consensus on disease management among relevant international societies. Thus, the usual clinical management of HDP is largely empirical. The current position statement of the Working Group 'Hypertension in Women' of the European Society of Hypertension (ESH) aims to employ the current evidence for the management of HDP, discuss the recommendations made in the 2023 ESH guidelines for the management of hypertension, and shed light on controversial issues in the field to stimulate future research.

Modified natural cycle allows a window of 7 days for frozen embryo transfer planning

RESEARCH QUESTION

Should ovulation be triggered in a modified natural cycle (mNC) with recombinant human chorionic gonadotrophin (rHCG) as soon as a mean follicle diameter of 17 mm is visible, or is more flexible planning possible?

DESIGN

This multicentre, retrospective, observational study of 3087 single frozen blastocyst transfers in mNC was carried out between January 2020 and September 2022. The inclusion criteria included endometrial thickness ≥7 mm and serum progesterone <1.5 ng/ml. The main outcome was ongoing pregnancy rate. Secondary end-points were pregnancy rate, implantation rate, clinical pregnancy rate and miscarriage rate. The mean follicle size at triggering was stratified into three groups (13.0-15.9, 16.0-18.9 and 19.0-22 mm).

RESULTS

The baseline characteristics between the groups did not vary significantly for age, body mass index and the donor's age for egg donation. No differences were found in pregnancy rate (64.5%, 60.2% and 57.4%; P = 0.19), clinical pregnancy rate (60.5%, 52.8% and 50.6%; P = 0.10), implantation rate (62.10%, 52.9% and 51.0%; P = 0.05) or miscarriage rate (15.0%, 22.2%; and 25.0%; P = 0.11). Although ongoing pregnancy rate (54.9%, 46.8% and 43.1%; P = 0.02) varied significantly in the univariable analysis, it was no longer significant after adjustment for the use of preimplantation genetic testing for aneuploidies and egg donation.

CONCLUSIONS

The findings showed rHCG could be flexibly administered with a mean follicle size between 13 and 22 mm as long as adequate endometrial characteristics are met, and serum progesterone is <1.5 ng/ml. Considering the follicular growth rate of 1-1.5 mm/day, this approach could allow a flexibility for FET scheduling of 6-7 days, simplifying mNC FET planning in clinical practice.

Clinical features of preeclampsia and hypertensive disorders in pregnancies after different frozen embryo transfer regimens

OBJECTIVES

To compare whether the clinical features of preeclampsia (PE) or gestational hypertension (GH) were different in pregnancies after a frozen embryo transfer (FET), depending on the FET regimen used.

STUDY DESIGN

A retrospective study including 58 pregnancies with PE and 64 pregnancies with GH, all with singleton live births. Pregnancies were stratified according to the presence or absence of a corpus luteum (CL).

MAIN OUTCOME MEASURES

Clinical characteristics of PE and GH, maternal background factors, postpartum hemorrhage (PPH), key perinatal outcomes.

RESULTS

Among PE patients, no difference was found in the clinical characteristics and in the maternal background factors, when comparing women with a CL to women without a CL. PE patients in the group without a CL had a hemorrhage of > 500 mL or > 1000 mL significantly more often than patients with a CL. Multivariable analyses confirmed this risk. Perinatal outcomes were similar. Among GH patients, there was no difference in the clinical features and maternal background factors, when comparing CL cycles to cycles without a CL. The amount of PPH was higher among the patients without a CL, but the frequency of a > 500 mL or > 1000 mL hemorrhage was similar between groups. No risk increase was seen in multivariable analyses.

CONCLUSIONS

Among FET patients with PE, the risk of PPH wasincreased in pregnancies after cycles without a CL, compared to cycles with a CL. The presence or absence of a CL did noteffectthe severity of PE and GH, the duration of pregnancy or blood pressure levels.

Current understanding of the pathogenesis of placenta accreta spectrum disorder with focus on mitochondrial function

AIM

The refinement of assisted reproductive technology, including the development of cryopreservation techniques (vitrification) and ovarian stimulation protocols, makes frozen embryo transfer (FET) an alternative to fresh ET and has contributed to the success of assisted reproductive technology. Compared with fresh ET cycles, FET cycles were associated with better in vitro fertilization outcomes; however, the occurrence of pregnancy-induced hypertension, preeclampsia, and placenta accreta spectrum (PAS) was higher in FET cycles. PAS has been increasing steadily in incidence as a life-threatening condition along with cesarean rates worldwide. In this review, we summarize the current understanding of the pathogenesis of PAS and discuss future research directions.

METHODS

A literature search was performed in the PubMed and Google Scholar databases.

RESULTS

Risk factors associated with PAS incidence include a primary defect of the decidua basalis or scar dehiscence, aberrant vascular remodeling, and abnormally invasive trophoblasts, or a combination thereof. Freezing, thawing, and hormone replacement manipulations have been shown to affect multiple cellular pathways, including cell proliferation, invasion, epithelial-to-mesenchymal transition (EMT), and mitochondrial function. Molecules involved in abnormal migration and EMT of extravillous trophoblast cells are beginning to be identified in PAS placentas. Many of these molecules were also found to be involved in mitochondrial biogenesis and dynamics.

CONCLUSION

The etiology of PAS may be a multifactorial genesis with intrinsic predisposition (e.g., placental abnormalities) and certain environmental factors (e.g., defective decidua) as triggers for its development. A distinctive feature of this review is its focus on the potential factors linking mitochondrial function to PAS development.

Ideal frozen embryo transfer regime

PURPOSE OF REVIEW

This review aims to compare evidence on four criteria (embryo implantation, obstetric outcomes, patient convenience, and IVF-unit efficiency) by analyzing published research on different endometrial preparation methods for frozen embryo transfer (FET).

RECENT FINDINGS

While the artificial-FET cycle provides advantages in scheduling and implantation, it falls short in ensuring optimal obstetric outcomes. In contrast, natural-FET ensures embryo implantation conditions if ovulation is correctly identified. Supplementing with exogenous progesterone shields against low corpus luteum progesterone secretion, crucial for positive obstetric outcomes. In mNC-FET, ovulation is hCG-triggered, closely resembling natural cycles and reducing monitoring visits for enhanced patient convenience.Letrozole is a recommended option for anovulatory patients, preserving endometrial thickness. It is cost-effective, less likely to induce multifollicular development than gonadotropins, and better tolerated.In a novel approach, the natural-proliferative-phase-FET initiates progesterone in an unmediated ovulatory cycle at 7 mm endometrial thickness, combining the benefits of a natural proliferative endometrium with the convenience of scheduled artificial cycles.

SUMMARY

The artificial cycle offers scheduling advantages, but may compromise obstetric outcomes. Natural FET relies on accurate ovulation timing for successful implantation. mNC-FET simplifies the process using hCG induction, minimizing clinic visits for improved convenience. Letrozole is highlighted as a cost-effective and well tolerated option in anovulatory patients. A recent innovative approach combines elements of natural and artificial cycles, showing promise for FET procedures.

Midluteal serum estradiol levels are associated with live birth rates in hormone replacement therapy frozen embryo transfer cycles: a cohort study

OBJECTIVE

To study whether midluteal serum estradiol (E2) levels are associated with the live birth rate in hormone replacement therapy frozen embryo transfer (HRT-FET) cycles in patients with optimal midluteal serum progesterone (P4) levels.

DESIGN

Observational prospective cohort study.

SETTING

Public fertility clinic.

PATIENTS

A total of 412 women had an HRT-FET cycle single blastocyst transfer from January 2020 to November 2022.

INTERVENTION

The HRT-FET cycle priming regimen included oral E2 (6mg/24 h) administered in the evening, followed by vaginal P4 (400mg/12 h). Serum E2 and P4 levels were measured using a standardized method, 2-4 hours after the latest P4 administration and 9-14 hours after E4 administration on the day of blastocyst transfer, day 6 of P4 administration. Patients with serum P4 levels (<11 ng/mL [35 nmol/L]) on the day of transfer received additional rectal P4 (400mg/12 h). No additional E2 dose was administered.

MAIN OUTCOME MEASURES

The primary outcome was the live birth rate (LBR) in relation to E2 levels at blastocyst transfer day.

RESULTS

The optimal serum E2 levels correlating with ongoing pregnancy were ≥292 pg/mL and <409 pg/mL (≥1,070 pmol/L and <1,500 pmol/L). The LBR was 59% (60/102) when E2 levels were within this range, whereas a significantly lower LBR of 39% (101/260) was seen in patients when E2 levels were <292 pg/mL (<1,070 pmol/L) and of 28% (14/50) when E2 levels were ≥409 pg/mL (≥1,500 pg/mL). In a logistic regression analysis, adjusting for serum P4 level ≥11 ng/mL or <11 ng/mL (≥35 nmol or <35 nmol/L) on the day of transfer, body mass index, age at oocyte retrieval, day 5 or 6 vitrified blastocysts, and blastocyst score, the adjusted risk difference of live birth was -0.21 (-0.32; -0.10) when the E2 level was <292 pg/mL (<1,070 pmol/L) and -0.31 (-0.45; -0.18) when the E2 level was ≥409 pg/mL (≥1,500 pmol/L) compared with E2 levels ≥292 pg/mL and <409 pg/mL (≥1,070 and <1,500 pmol/L). Importantly, only 25% of patents had optimal levels.

CONCLUSION

The study shows a significant association between serum E2 levels and reproductive outcomes in an HRT-FET cohort in which optimal serum P4 levels were secured. Midluteal serum E2 levels are associated with the LBR in HRT-FET cycles, and E2 levels should neither be too high nor too low.

CLINICAL TRIAL REGISTRATION NUMBER

EudraCT No.: 2019-001539-29.

Clinical outcomes of frozen-thawed embryo transfer in natural cycles with luteinized unruptured follicles

OBJECTIVE

To assess the effect of luteinized unruptured follicles (LUF) on frozen-thawed embryo transfer cycles performed in natural cycles (FET-NC).

METHODS

Retrospective cohort study, held in a university hospital with 3415 cycles for frozen-thawed embryo transfer, performed between June 2019 and September 2022. Using propensity score matching, 242 patients with a diagnosis of LUF (LUF group) were matched with 484 ovulated patients (ovulation group). Stratified by the type of embryo transferred, the LUF group included 168 blastocyst transfer patients (blastocyst group) and 74 cleavage-stage embryo transfer patients (cleavage-embryo group). The ovulation group included 324 patients with blastocyst transfer (blastocyst group) and 160 patients with transferred cleavage-stage embryos. Clinical pregnancy rate was retrospectively analyzed between the LUF and ovulation groups, as well as between each subgroup.

RESULTS

After using propensity score matching, the general characteristics of the LUF and ovulation groups were similar. The implantation and clinical pregnancy rates in the LUF group were not significantly different from those in the ovulation group (44.98 % vs. 45.29 %, p = 0.93; 53.72 % vs. 52.48 %, p = 0.75). The implantation and pregnancy rates of transferred cleavage-stage embryos in the LUF group were also not significantly different from those in the ovulation group (32.39 % vs. 36.40 %, p = 0.42; 47.30 % vs. 47.50 %, p = 0.98). The implantation and pregnancy rates of transferred blastocysts in the LUF group were also not significantly different from those in the ovulation group (53.11 % vs. 52.03 %, p = 0.82; 56.55 % vs. 54.94 %, p = 0.73). There was also no significant difference in the miscarriage rate between the groups.

CONCLUSION

In the natural cycle, LUF does not affect the clinical pregnancy outcomes of FET. If adequate luteal support is given, the clinical pregnancy outcomes were similar between the LUF group and ovulation group.

Association of duration of embryo culture with risk of large for gestational age delivery in cryopreserved embryo transfer cycles

OBJECTIVE

To examine the relationship between the day of embryo cryopreservation and large for gestational age (LGA) infants in women undergoing frozen embryo transfers (FETs) after cryopreservation on days 2-7 after fertilization and to compare the risk of the day of embryo cryopreservation to other possible risk factors of LGA after FET cycles.

DESIGN

Retrospective cohort study.

SETTING

Society of Assisted Reproduction Clinical Outcomes Reporting System.

PATIENTS

Women undergoing FET cycles.

INTERVENTION

Day of cryopreservation.

MAIN OUTCOME MEASURE

Singleton LGA infant.

RESULTS

A total of 33,030 (18.2%) FET cycles in the study group (n = 181,592) resulted in LGA infants during the study period of 2014-2019. There was an increase in LGA risk when cryopreservation was performed from day 2 (13.7%) to days 3-7 (14.4%, 15.0%, 18.2%, 18.5%, and 18.9%). In the log-binomial model, the risk increased compared with days 2-3 combined when cryopreservation was performed on days 5-7 (adjusted relative risk [aRR] 1.32, 95% confidence interval [CI] 1.22-1.44 for day 5, aRR 1.34, 95% CI 1.23-1.46 for day 6, and aRR 1.42, 95% CI 1.25-1.61 for day 7). Other factors most associated with LGA risk in the log-binomial model were preterm parity of >3 compared with 0 (aRR 1.82, 95% CI 1.24-2.69) and body mass index (BMI) of >35 kg/m2 compared with normal weight (aRR 1.94, 95% CI 1.88-2.01). Increasing gravity, parity, BMI, number of oocytes, and embryo grade were also associated with LGA in this model. Asian, Black, Hispanic, and combined Hawaiian and Pacific Islander were protective factors in the model compared with White patients. Low BMI (<18.5 kg/m2) was also considered a protective factor in the model compared with normal BMI.

CONCLUSION

Duration of embryo culture was associated with an increased risk of LGA in this study cohort when controlling for known confounders such as maternal BMI and parity. This study sheds new light on the possible link between FET and LGA infants.

Assessing obstetric outcomes: A systematic review and meta-analysis comparing fresh, artificial, and natural thaw embryo transfer cycles

BACKGROUND

The increasing utilisation of in vitro fertilisation (IVF) has prompted significant interest in determining the optimal endometrial environment to increase pregnancy rates and minimise the obstetric complications associated with various embryo transfer strategies.

AIMS

To determine which cycle is associated with increased obstetric complications: fresh embryo transfer (FreshET), natural thaw (NatThawET) or artificial thaw (ArtThawET). Outcomes of interest included: hypertensive disorders of pregnancy (HDP), gestational diabetes (GD), pre-term birth (PTB), post-partum haemorrhage (PPH) and large for gestational age (LGA).

MATERIALS AND METHODS

A comprehensive search of MEDLINE, EMBASE, CENTRAL, and PUBMED was conducted from 1947 to May 17, 2022. Two independent reviewers carried out the screening, and data extraction for the following comparisons: ArtThawET vs NatThawET, ArtThawET vs FreshET, and NatThawET vs FreshET. Meta-analysis was conducted using a fixed-effect Mantel-Haenszel model. The quality of the studies was assessed using GRADEpro.

RESULTS

A total of 23 studies were included in this review. ArtThawET was associated with a significantly increased odds of HDP (odds ratio (OR) 1.76, confidence interval (CI) 1.66-1.86), PTB (OR 1.18, CI 1.13-1.23), PPH (OR 2.61, CI 2.3-2.97) and LGA (OR 1.11, CI 1.07-1.15), compared to NatThawET. ArtThawET was also associated with increased odds of HDP (OR 2.13, CI 1.89-2.4), PPH (OR 3.52, CI 3.06-4.04) and LGA (OR 2.12, CI 1.77-2.56), compared to FreshET. Furthermore, NatThawET demonstrated increased odds of HDP (OR 1.20, CI 1.11-1.29), PPH (OR 1.25, CI 1.14-1.38) and LGA (OR 1.85, CI 1.66-2.07) compared to FreshET.

CONCLUSION

When clinically feasible, ArtThawET should be avoided as a first-line option for IVF to reduce the risk of obstetric complications. An adequately powered, multicentre randomised controlled trial is necessary to confirm these findings and investigate the underlying pathophysiology.

Pathologic maternal and neonatal outcomes associated with programmed embryo transfer

PURPOSE

In this first of two companion papers, we critically review the evidence recently published in the primary literature, which addresses adverse maternal and neonatal pregnancy outcomes associated with programmed embryo transfer cycles. We next consider whether these pathological pregnancy outcomes might be attributable to traditional risk factors, unknown parental factors, embryo culture, culture duration, or cryopreservation. Finally, in the second companion article, we explore potential etiologies and suggest strategies for prevention.

METHODS

Comprehensive review of primary literature.

RESULTS

The preponderance of retrospective and prospective observational studies suggests that increased risk for hypertensive disorders of pregnancy (HDP) and preeclampsia in assisted reproduction involving autologous embryo transfer is associated with programmed cycles. For autologous frozen embryo transfer (FET) and singleton live births, the risk of developing HDP and preeclampsia, respectively, was less for true or modified natural and stimulated cycles relative to programmed cycles: OR 0.63 [95% CI (0.57-0.070)] and 0.44 [95% CI (0.40-0.50)]. Though data are limited, the classification of preeclampsia associated with programmed autologous FET was predominantly late-onset or term disease. Other adverse pregnancy outcomes associated with autologous FET, especially programmed cycles, included increased prevalence of large for gestational age infants and macrosomia, as well as higher birth weights. In one large registry study, FET was associated with fetal overgrowth of a symmetrical nature. Postterm birth and placenta accreta not associated with prior cesarean section, uterine surgery, or concurrent placenta previa were also associated with autologous FET, particularly programmed cycles. The heightened risk of these pathologic pregnancy outcomes in programmed autologous FET does not appear to be attributable to traditional risk factors, unknown parental factors, embryo culture, culture duration, or cryopreservation, although the latter may contribute a modest degree of increased risk for fetal overgrowth and perhaps HDP and preeclampsia in FET irrespective of the endometrial preparation.

CONCLUSIONS

Programmed autologous FET is associated with an increased risk of several, seemingly diverse, pathologic pregnancy outcomes including HDP, preeclampsia, fetal overgrowth, postterm birth, and placenta accreta. Though the greater risk for preeclampsia specifically associated with programmed autologous FET appears to be well established, further research is needed to substantiate the limited data currently available suggesting that the classification of preeclampsia involved is predominately late-onset or term. If substantiated, then this knowledge could provide insight into placental pathogenesis, which has been proposed to differ between early- and late-onset or term preeclampsia (see companion paper for a discussion of potential mechanisms). If a higher prevalence of preeclampsia with severe features as suggested by some studies is corroborated in future investigations, then the danger to maternal and fetal/neonatal health is considerably greater with severe disease, thus increasing the urgency to find preventative measures. Presupposing significant overlap of these diverse pathologic pregnancy outcomes within subjects who conceive by programmed embryo transfer, there may be common etiologies.

Pathologic maternal and neonatal outcomes associated with programmed embryo transfer: potential etiologies and strategies for prevention

PURPOSE

In the first of two companion papers, we comprehensively reviewed the recent evidence in the primary literature, which addressed the increased prevalence of hypertensive disorders of pregnancy, late-onset or term preeclampsia, fetal overgrowth, postterm birth, and placenta accreta in women conceiving by in vitro fertilization. The preponderance of evidence implicated frozen embryo transfer cycles and, specifically, those employing programmed endometrial preparations, in the higher risk for these adverse maternal and neonatal pregnancy outcomes. Based upon this critical appraisal of the primary literature, we formulate potential etiologies and suggest strategies for prevention in the second article.

METHODS

Comprehensive review of primary literature.

RESULTS

Presupposing significant overlap of these apparently diverse pathological pregnancy outcomes within subjects who conceive by programmed autologous FET cycles, shared etiologies may be at play. One plausible but clearly provocative explanation is that aberrant decidualization arising from suboptimal endometrial preparation causes greater than normal trophoblast invasion and myometrial spiral artery remodeling. Thus, overly robust placentation produces larger placentas and fetuses that, in turn, lead to overcrowding of villi within the confines of the uterine cavity which encroach upon intervillous spaces precipitating placental ischemia, oxidative and syncytiotrophoblast stress, and, ultimately, late-onset or term preeclampsia. The absence of circulating corpus luteal factors like relaxin in most programmed cycles might further compromise decidualization and exacerbate the maternal endothelial response to deleterious circulating placental products like soluble fms-like tyrosine kinase-1 that mediate disease manifestations. An alternative, but not mutually exclusive, determinant might be a thinner endometrium frequently associated with programmed endometrial preparations, which could conspire with dysregulated decidualization to elicit greater than normal trophoblast invasion and myometrial spiral artery remodeling. In extreme cases, placenta accreta could conceivably arise. Though lower uterine artery resistance and pulsatility indices observed during early pregnancy in programmed embryo transfer cycles are consistent with this initiating event, quantitative analyses of trophoblast invasion and myometrial spiral artery remodeling required to validate the hypothesis have not yet been conducted.

CONCLUSIONS

Endometrial preparation that is not optimal, absent circulating corpus luteal factors, or a combination thereof are attractive etiologies; however, the requisite investigations to prove them have yet to be undertaken. Presuming that in ongoing RCTs, some or all adverse pregnancy outcomes associated with programmed autologous FET are circumvented or mitigated by employing natural or stimulated cycles instead, then for women who can conceive using these regimens, they would be preferable. For the 15% or so of women who require programmed FET, additional research as suggested in this review is needed to elucidate the responsible mechanisms and develop preventative strategies.

Blood pressure and lipid profiles in children born after ART with frozen embryo transfer

STUDY QUESTION

Are blood pressure (BP) and lipid profiles different between children conceived after ART with frozen embryo transfer (FET), fresh embryo transfer (fresh-ET), and natural conception (NC)?

SUMMARY ANSWER

Girls conceived after FET had significantly higher systolic BP and heart rate compared with girls born after fresh-ET; boys conceived after FET had a slightly more favourable lipid profile compared with boys born after fresh-ET and NC.

WHAT IS KNOWN ALREADY

Children conceived after ART with FET are more often born large for gestational age (LGA). LGA in general increases the risk of obesity, diabetes, and cardiovascular disease later in life. Studies on mice and humans on the whole ART population have raised concerns about premature vascular ageing and higher BP. The cardiovascular health of children born after FET is scarcely explored and the results are diverging.

STUDY DESIGN SIZE DURATION

This study was part of the cohort study 'Health in Childhood following Assisted Reproductive Technology' (HiCART), which included 606 singletons (292 boys) born between December 2009 and December 2013: 200 children were conceived after FET; 203 children were conceived after fresh-ET; and 203 children were conceived naturally and matched for birth year and sex. The study period lasted from January 2019 to September 2021.

PARTICIPANTS/MATERIALS SETTING METHODS

The included children were 7-10 years of age at examination and underwent a clinical examination with anthropometric measurements, pubertal staging, and BP measurement. Additionally, a fasting blood sample was collected and analysed for cholesterol, low-density lipoproteins (LDL), high-density lipoproteins (HDL), and triglycerides. Systolic and diastolic BP were converted to standard deviation scores (SDS) using an appropriate reference and accounting for height (SDS) of the child. The three study groups were compared pairwise using a univariate linear regression model. Mean differences were adjusted for confounders using multiple linear regression analyses.

MAIN RESULTS AND THE ROLE OF CHANCE

Girls and boys conceived after FET had significantly higher birthweight (SDS) compared with naturally conceived peers (mean difference: girls: 0.35, 95% CI (0.06-0.64), boys: 0.35, 95% CI (0.03-0.68)). Girls conceived after FET had significantly higher systolic BP (SDS) and heart rate compared with girls conceived after fresh-ET (adjusted mean difference: systolic BP (SDS): 0.25 SDS, 95% CI (0.03-0.47), heart rate: 4.53, 95% CI (0.94-8.13)). Regarding lipid profile, no significant differences were found between the three groups of girls. For the boys, no significant differences were found for BP and heart rate. Lipid profiles were more favourable in boys born after FET compared with both boys conceived after fresh-ET and NC. All outcomes were adjusted for parity, maternal BMI at early pregnancy, smoking during pregnancy, educational level, birthweight, breastfeeding, child age at examination, and onset of puberty.

LIMITATIONS REASONS FOR CAUTION

The participation rate varied from 18 to 42% in the three groups, and therefore selection bias cannot be excluded. However, extensive non-participant analyses were performed that showed almost no differences in background characteristics between participants and non-participants in the three groups, making selection bias less likely.

WIDER IMPLICATIONS OF THE FINDINGS

The higher birthweight in children conceived after FET was associated with increased systolic BP (SDS) and heart rate in girls conceived after FET compared with fresh-ET. This may be an early indicator of compromised long-term cardiovascular health in this group. The study was not powered to investigate these outcomes and further studies are therefore warranted to confirm the findings.

STUDY FUNDING/COMPETING INTERESTS

The study was funded by the Novo Nordisk Foundation (grant number: NNF18OC0034092, NFF19OC0054340) and Rigshospitalets Forskningsfond. The authors have no conflicts of interest to declare.

TRIAL REGISTRATION NUMBER

ClinicalTrials.gov identifier: NCT03719703.

The impact of serum estradiol and progesterone levels during implantation on obstetrical complications and perinatal outcomes in frozen embryo transfer

BACKGROUND

This study sought to evaluate obstetric complications and perinatal outcomes in frozen embryo transfer (FET) using either a natural cycle (NC-FET) or a hormone therapy cycle (HT-FET). Furthermore, we investigated how serum levels of estradiol (E2) and progesterone (P4) on the day of and 3 days after embryo transfer (ET) correlated with clinical outcomes in the two groups.

METHODS

We conducted a retrospective, single-center study from January 1, 2015, to December 31, 2019. The study included couples who underwent NC-FET or HT-FET resulting in a singleton live birth. Serum levels of E2 and P4 were measured on the day of and 3 days after ET. The primary outcomes assessed were preterm birth rate, low birth weight, macrosomia, hypertensive disorders in pregnancy, gestational diabetes mellitus, postpartum hemorrhage, and placenta-related complications.

RESULTS

A total of 229 singletons were included, with 49 in the NC-FET group and 180 in the HT-FET group. There were no significant differences in obstetric complications and perinatal outcomes between the two groups. The NC-FET group had significantly higher serum levels of P4 (17.2 ng/mL vs 8.85 ng/mL; p < 0.0001) but not E2 (144 pg/mL vs 147 pg/mL; p = 0.69) on the day of ET. Additionally, 3 days after ET, the NC-FET group had significantly higher levels of both E2 (171 pg/mL vs 140.5 pg/mL; p = 0.0037) and P4 (27.3 ng/mL vs 11.7 ng/mL; p < 0.0001) compared with the HT-FET group.

CONCLUSION

Our study revealed that although there were significant differences in E2 and P4 levels around implantation between the two groups, there were no significant differences in obstetric complications and perinatal outcomes. Therefore, the hormonal environment around implantation did not appear to be the primary cause of differences in obstetric and perinatal outcomes between the two EM preparation methods used in FET.

Major postpartum haemorrhage after frozen embryo transfer: A population-based study

OBJECTIVE

To investigate the effect on major postpartum haemorrhage (PPH) of mode of conception, differentiating between naturally conceived pregnancies, fresh embryo in vitro fertilisation (fresh-IVF) and frozen embryo transfer (frozen-IVF).

DESIGN

Retrospective cohort study.

SETTING

The French Burgundy Perinatal Network database, including all deliveries from 2006 to 2020, was linked to the regional blood centre database.

POPULATION OR SAMPLE

In all, 244 336 women were included, of whom 240 259 (98.3%) were singleton pregnancies.

METHODS

The main analyses were conducted in singleton pregnancies, including 237 608 naturally conceived, 1773 fresh-IVF and 878 frozen-IVF pregnancies. Multivariate logistic regression models adjusted on maternal age, body mass index, smoking, parity, induction of labour, hypertensive disorders, diabetes, placenta praevia and/or accreta, history of caesarean section, mode of delivery, birthweight, birth place and year of delivery, were used.

MAIN OUTCOME MEASURES

Major PPH was defined as PPH requiring blood transfusion and/or emergency surgery and/or interventional radiology.

RESULTS

The prevalence of major PPH was 0.74% (n = 1749) in naturally conceived pregnancies, 1.92% (n = 34) in fresh-IVF pregnancies, and 3.30% (n = 29) in frozen-IVF pregnancies. The risk of major PPH was higher in frozen-IVF pregnancies than in both naturally conceived pregnancies (adjusted odds ratio [aOR] 2.63, 95% CI 1.68-4.10) and fresh-IVF pregnancies (aOR 2.78, 95% CI 1.44-5.35).

CONCLUSIONS

We found that frozen-IVF pregnancies have a higher risk of major PPH and they should be subject to increased vigilance in the delivery room.

Factors and outcomes for placental anomalies: An umbrella review of systematic reviews and meta-analyses

Background

Placental anomalies, including placenta previa (PP), placenta accreta spectrum disorders (PAS), and vase previa (VP), are associated with several adverse foetal-neonatal and maternal complications. However, there is still a lack of robust evidence on the pathogenesis and adverse outcomes of the diseases. Through this umbrella review, we aimed to systematically review existing meta-analyses exploring the factors and outcomes for pregnancy women with placental anomalies.

Methods

We searched PubMed, Embase, Web of Science, and the Cochrane Library from inception to February 2023. We used AMSTAR 2 to assess the quality of the reviews and estimated the pooled risk and 95% confidence intervals (CIs) for each meta-analysis.

Results

We included 34 meta-analyses and extracted 55 factors (27 for PP, 22 for PAS, and 6 for VP) and 16 outcomes (12 for PP, and 4 for VP) to assess their credibility. Seven factors (maternal cocaine use (for PP), uterine leiomyoma (for PP), prior abortion (spontaneous) (PP), threatened miscarriage (PP), maternal obesity (PP), maternal smoking (PAS), male foetus (PAS)) had high epidemiological evidence. Twelve factors and six outcomes had moderate epidemiological evidence. Twenty-two factors and eight outcomes showed significant association, but with weak credibility.

Conclusions

We found varying levels of evidence for placental anomalies of different factors and outcomes in this umbrella review.

Registration

PROSPERO: CRD42022300160.

Endometrial preparation protocols prior to frozen embryo transfer - convenience or safety?

The number of frozen embryo transfer (FET) cycles is increasing rapidly worldwide. Different endometrial preparations for FET result in comparable live birth rates. However, several recent publications have reported higher maternal risks for hypertensive disorders of pregnancy (HDP), pre-eclampsia and postpartum haemorrhage (PPH) in programmed cycles (PC-FET) compared with natural cycles and modified natural cycles with an intact corpus luteum. Nevertheless, PC-FET is frequently used in ovulatory women despite the increased risks for HDP, pre-eclampsia and PPH. Although randomized controlled studies have been suggested, PC-FET raises several methodological problems. Large study populations would be required to investigate the outcomes in question, and the inclusion of ovulatory women, where the intervention may increase the risk of a negative outcome, is ethically troublesome. In the authors' opinion, the existing evidence from large observational studies and systematic reviews is sufficiently strong to recommend an endometrial preparation strategy that aims to maintain or stimulate the corpus luteum to minimize the risk of HDP and pre-eclampsia after FET cycles.

Thick endometrium is associated with hypertensive disorders of pregnancy in programmed frozen-thawed embryo transfers: a retrospective analysis of 2,275 singleton deliveries

OBJECTIVE

To investigate whether endometrial thickness (EMT) acts as a contributing factor to adverse perinatal outcomes in programmed frozen-thawed embryo transfer (FET) cycles.

DESIGN

Retrospective cohort study.

SETTING

University-based reproductive medical center.

SUBJECT

The study included singleton live births resulting from programmed FET cycles that took place between January 2017 and April 2022 (N = 2,275 cycles).

EXPOSURE

The EMT measurement conducted on the day of progesterone initiation was utilized. Programmed FET cycles with EMT <7 mm were excluded from consideration. All included subjects were divided into 4 groups on the basis of the 10th, 50th, and 90th percentiles of EMT: group Ⅰ (EMT ≤8 mm, n = 193), group Ⅱ (EMT = 8.1-10 mm, n = 1,261), group Ⅲ (EMT = 10.1-12 mm, n = 615), and group Ⅳ (EMT >12 mm, n = 206). After adjusting for patient demographics and FET parameters, logistic regression analysis and restricted cubic spline were used to investigate the relationship between EMT and perinatal outcomes. The group Ⅱ (EMT = 8.1-10 mm) served as a reference.

MAIN OUTCOME MEASURE(S)

The primary outcome measure was the hypertensive disorders of pregnancy (HDP). Secondary outcomes included gestational diabetes mellitus, cesarean delivery, placenta previa, premature rupture of membrane, birthweight, preterm birth, low birthweight, macrosomia, small for gestational age, large for gestational age and neonatal morbidity.

RESULTS(S)

The incidence of HDP was substantially elevated in group Ⅳ when compared with the other groups (5.7% vs. 4.1% vs. 5.7% vs. 9.7% for groups Ⅰ-Ⅳ, respectively). In addition, group I displayed a higher incidence of cesarean deliveries, whereas both group I and group IV exhibited an elevated prevalence of placenta previa. After adjusting for confounding factors, patients in group IV exhibited a significantly increased risk of HDP (adjusted odds ratio [OR] = 2.03, 95% confidence interval [CI] 1.13-3.67) as compared with patients in the reference group. The restricted cubic spline model revealed a nonlinear association between EMT and the odds of HDP on continuous scales. In comparison to women with an EMT of 9.5 mm, there was no significant change in the risk of HDP in women with EMT between 7 and 11 mm, as indicated by adjusted ORs of 1.37 (95% CI 0.41-4.52), 1.34 (95% CI 0.73-2.47), 1.13 (95% CI 0.79-1.62), 1.04 (95% CI 0.87-1.25), and 1.46 (95% CI 0.81-2.65), respectively. However, the risk of HDP was significantly higher in women with EMT ranging from 12 to 15 mm, with adjusted ORs of 1.86 (95% CI 1.03-3.35), 2.33 (95% CI 1.32-4.12), 2.92 (95% CI 1.52-5.60), and 3.62 (95% CI 1.63-8.04), respectively.

CONCLUSION(S)

This study demonstrated a noteworthy association between EMT and adverse perinatal outcomes during the programmed FET cycles. Specifically, a thick endometrium (EMT >12 mm) was independently associated with an increased risk of developing HDP, whereas the optimal EMT for reducing the risk of HDP was at around 9-10 mm.

AI language models in human reproduction research: exploring ChatGPT's potential to assist academic writing

Artificial intelligence (AI)-driven language models have the potential to serve as an educational tool, facilitate clinical decision-making, and support research and academic writing. The benefits of their use are yet to be evaluated and concerns have been raised regarding the accuracy, transparency, and ethical implications of using this AI technology in academic publishing. At the moment, Chat Generative Pre-trained Transformer (ChatGPT) is one of the most powerful and widely debated AI language models. Here, we discuss its feasibility to answer scientific questions, identify relevant literature, and assist writing in the field of human reproduction. With consideration of the scarcity of data on this topic, we assessed the feasibility of ChatGPT in academic writing, using data from six meta-analyses published in a leading journal of human reproduction. The text generated by ChatGPT was evaluated and compared to the original text by blinded reviewers. While ChatGPT can produce high-quality text and summarize information efficiently, its current ability to interpret data and answer scientific questions is limited, and it cannot be relied upon for a literature search or accurate source citation due to the potential spread of incomplete or false information. We advocate for open discussions within the reproductive medicine research community to explore the advantages and disadvantages of implementing this AI technology. Researchers and reviewers should be informed about AI language models, and we encourage authors to transparently disclose their use.

Overweight or obesity in children born after assisted reproductive technologies in Denmark: A population-based cohort study

BACKGROUND

The association between assisted reproductive technologies (ARTs) and the body mass index (BMI) of children remains controversial. Confounding by morbidity and other factors associated with parental infertility may have biased studies comparing children born after ART with children born after no treatment. We investigated the associations between different fertility treatments and BMI in children at age 5 to 8 years, adjusting for and stratifying by causes of parental infertility.

METHODS AND FINDINGS

This Danish cohort study included 327,301 children born between 2007 and 2012 (51% males, median age at follow-up 7 years). Of these, 13,675 were born after ART, 7,728 were born after ovulation induction with or without intrauterine insemination [OI/IUI], and 305,898 were born after no fertility treatments. Using the International Obesity Task Force (IOTF) standards, we defined overweight (BMI ≥ IOTF-25) and obesity (BMI ≥ IOTF-30). We compared children born after ART versus OI/IUI; intracytoplasmic sperm injection (ICSI) versus conventional in vitro fertilization (IVF); and frozen-thawed versus fresh embryo transfer and estimated crude and adjusted prevalences of children with overweight or obesity at age 5 to 8 years, prevalence odds ratios (PORs), and differences in mean BMI z-scores. Adjustment was performed using stabilized inverse probability of treatment weights, including parity, year of conception, parental causes of infertility, age, educational level, comorbidities, maternal country of origin, BMI, and smoking as covariates. The crude prevalence of obesity was 1.9% in children born after ART, 2.0% in those born after OI/IUI, and 2.7% in those born after no fertility treatment. After adjustment, children born after ART and OI/IUI had the same prevalence of being overweight (11%; POR 1.00, 95% confidence interval [CI] 0.91 to 1.11; p = 0.95) or obese (1.9%; POR 1.01, 95% CI 0.79 to 1.29; p = 0.94). Comparison of ICSI with conventional IVF yielded similar pattern (POR 0.95, 95% CI 0.83 to 1.07; p = 0.39 for overweight and POR 1.16, 95% CI 0.84 to 1.61; p = 0.36 for obesity). Obesity was more prevalent after frozen-thawed (2.7%) than fresh embryo transfer (1.8%) (POR 1.54, 95% CI 1.09 to 2.17; p = 0.01). The associations between fertility treatments and BMI were only modestly different in subgroups defined by the cause of infertility. Study limitations include potential residual confounding, restriction to live births, and lack of detailed technical information about the IVF procedures.

CONCLUSIONS

We found no association with BMI at age 5 to 8 years when comparing ART versus OI/IUI or when comparing ICSI versus conventional IVF. However, use of frozen-thawed embryo transfer was associated with a 1.5-fold increased risk of obesity compared to fresh embryo transfer. Despite an elevated relative risk, the absolute risk difference was low.

Association between endometrial thickness and birthweight of singletons from vitrified-warmed cycles: a retrospective cohort study

RESEARCH QUESTION

What is the association between endometrial thickness (EMT) and the birthweight of singleton infants born from frozen-thawed embryo transfer cycles?

DESIGN

This retrospective cohort study was conducted from January 2016 to December 2019. Participants were categorized into a natural cycle (NC, n = 8132) group and hormone replacement therapy (HRT, n = 4975) group. Only singleton deliveries were included. The primary outcomes were measures of birthweight and relevant indexes. Multivariable logistic regression and multivariable-adjusted linear regression models that incorporated restricted cubic splines were used.

RESULTS

In the HRT group, the risk of delivering a small for gestational age (SGA) infant was increased in women with an EMT <8.0 mm (adjusted odds ratio [aOR] 1.85, 95% confidence interval [CI] 1.17-2.91) compared with women with an EMT of 8.0 to <12.0 mm, and increased with an EMT ≥12.0 mm (aOR 1.85, 95% CI 1.03-3.33). An inverted U-shaped relationship was found between EMT and birthweight in women with HRT. No significant differences were shown in birthweight z-score, or being SGA or large for gestational age, in singletons among the three EMT groups in the natural cycles.

CONCLUSIONS

A thinner endometrium seen in women undergoing HRT cycles was associated with a lower birthweight z-score, as well as a higher risk of SGA. However, no significant association was observed between EMT and birthweight z-score or SGA in the NC group. It is noteworthy that a thicker endometrium was not associated with a higher birthweight in frozen-thawed embryo transfer (FET) cycles. Women with a thin endometrium who achieve pregnancy require specialized attention, particularly if they are undergoing FET with HRT cycles.

Good practice recommendations on add-ons in reproductive medicine†

STUDY QUESTION

Which add-ons are safe and effective to be used in ART treatment?

SUMMARY ANSWER

Forty-two recommendations were formulated on the use of add-ons in the diagnosis of fertility problems, the IVF laboratory and clinical management of IVF treatment.

WHAT IS KNOWN ALREADY

The innovative nature of ART combined with the extremely high motivation of the patients has opened the door to the wide application of what has become known as 'add-ons' in reproductive medicine. These supplementary options are available to patients in addition to standard fertility procedures, typically incurring an additional cost. A diverse array of supplementary options is made available, encompassing tests, drugs, equipment, complementary or alternative therapies, laboratory procedures, and surgical interventions. These options share the common aim of stating to enhance pregnancy or live birth rates, mitigate the risk of miscarriage, or expedite the time to achieving pregnancy.

STUDY DESIGN, SIZE, DURATION

ESHRE aimed to develop clinically relevant and evidence-based recommendations focusing on the safety and efficacy of add-ons currently used in fertility procedures in order to improve the quality of care for patients with infertility.

PARTICIPANTS/MATERIALS, SETTING, METHODS

ESHRE appointed a European multidisciplinary working group consisting of practising clinicians, embryologists, and researchers who have demonstrated leadership and expertise in the care and research of infertility. Patient representatives were included in the working group. To ensure that the guidelines are evidence-based, the literature identified from a systematic search was reviewed and critically appraised. In the absence of any clear scientific evidence, recommendations were based on the professional experience and consensus of the working group. The guidelines are thus based on the best available evidence and expert agreement. Prior to publication, the guidelines were reviewed by 46 independent international reviewers. A total of 272 comments were received and incorporated where relevant.

MAIN RESULTS AND THE ROLE OF CHANCE

The multidisciplinary working group formulated 42 recommendations in three sections; diagnosis and diagnostic tests, laboratory tests and interventions, and clinical management.

LIMITATIONS, REASONS FOR CAUTION

Of the 42 recommendations, none could be based on high-quality evidence and only four could be based on moderate-quality evidence, implicating that 95% of the recommendations are supported only by low-quality randomized controlled trials, observational data, professional experience, or consensus of the development group.

WIDER IMPLICATIONS OF THE FINDINGS

These guidelines offer valuable direction for healthcare professionals who are responsible for the care of patients undergoing ART treatment for infertility. Their purpose is to promote safe and effective ART treatment, enabling patients to make informed decisions based on realistic expectations. The guidelines aim to ensure that patients are fully informed about the various treatment options available to them and the likelihood of any additional treatment or test to improve the chance of achieving a live birth.

STUDY FUNDING/COMPETING INTEREST(S)

All costs relating to the development process were covered from ESHRE funds. There was no external funding of the development process or manuscript production. K.L. reports speakers fees from Merck and was part of a research study by Vitrolife (unpaid). T.E. reports consulting fees from Gynemed, speakers fees from Gynemed and is part of the scientific advisory board of Hamilton Thorne. N.P.P. reports grants from Merck Serono, Ferring Pharmaceutical, Theramex, Gedeon Richter, Organon, Roche, IBSA and Besins Healthcare, speakers fees from Merck Serono, Ferring Pharmaceutical, Theramex, Gedeon Richter, Organon, Roche, IBSA and Besins Healthcare. S.R.H. declares being managing director of Fertility Europe, a not-for-profit organization receiving financial support from ESHRE. I.S. is a scientific advisor for and has stock options from Alife Health, is co-founder of IVFvision LTD (unpaid) and received speakers' fee from the 2023 ART Young Leader Prestige workshop in China. A.P. reports grants from Gedeon Richter, Ferring Pharmaceuticals and Merck A/S, consulting fees from Preglem, Novo Nordisk, Ferring Pharmaceuticals, Gedeon Richter, Cryos and Merck A/S, speakers fees from Gedeon Richter, Ferring Pharmaceuticals, Merck A/S, Theramex and Organon, travel fees from Gedeon Richter. The other authors disclosed no conflicts of interest.

DISCLAIMER

This Good Practice Recommendations (GPRs) document represents the views of ESHRE, which are the result of consensus between the relevant ESHRE stakeholders and are based on the scientific evidence available at the time of preparation.ESHRE GPRs should be used for information and educational purposes. They should not be interpreted as setting a standard of care or bedeemedinclusive of all proper methods of care, or be exclusive of other methods of care reasonably directed to obtaining the same results.Theydo not replace the need for application of clinical judgement to each individual presentation, or variations based on locality and facility type.Furthermore, ESHRE GPRs do not constitute or imply the endorsement, or favouring, of any of the included technologies by ESHRE.

The HERA (Hyper-response Risk Assessment) Delphi consensus for the management of hyper-responders in in vitro fertilization

PURPOSE

To provide agreed-upon guidelines on the management of a hyper-responsive patient undergoing ovarian stimulation (OS) METHODS: A literature search was performed regarding the management of hyper-response to OS for assisted reproductive technology. A scientific committee consisting of 4 experts discussed, amended, and selected the final statements. A priori, it was decided that consensus would be reached when ≥66% of the participants agreed, and ≤3 rounds would be used to obtain this consensus. A total of 28/31 experts responded (selected for global coverage), anonymous to each other.

RESULTS

A total of 26/28 statements reached consensus. The most relevant are summarized here. The target number of oocytes to be collected in a stimulation cycle for IVF in an anticipated hyper-responder is 15-19 (89.3% consensus). For a potential hyper-responder, it is preferable to achieve a hyper-response and freeze all than aim for a fresh transfer (71.4% consensus). GnRH agonists should be avoided for pituitary suppression in anticipated hyper-responders performing IVF (96.4% consensus). The preferred starting dose in the first IVF stimulation cycle of an anticipated hyper-responder of average weight is 150 IU/day (82.1% consensus). ICoasting in order to decrease the risk of OHSS should not be used (89.7% consensus). Metformin should be added before/during ovarian stimulation to anticipated hyper-responders only if the patient has PCOS and is insulin resistant (82.1% consensus). In the case of a hyper-response, a dopaminergic agent should be used only if hCG will be used as a trigger (including dual/double trigger) with or without a fresh transfer (67.9% consensus). After using a GnRH agonist trigger due to a perceived risk of OHSS, luteal phase rescue with hCG and an attempt of a fresh transfer is discouraged regardless of the number of oocytes collected (72.4% consensus). The choice of the FET protocol is not influenced by the fact that the patient is a hyper-responder (82.8% consensus). In the cases of freeze all due to OHSS risk, a FET cycle can be performed in the immediate first menstrual cycle (92.9% consensus).

CONCLUSION

These guidelines for the management of hyper-response can be useful for tailoring patient care and for harmonizing future research.

Impact of Endometrial Preparation on the Maternal and Fetal Cardiovascular Variables of the First Trimester Combined Screening Test

The modality of endometrial preparation for the transfer of frozen-thawed embryos may influence maternal and fetal adaptation to pregnancy and could thus impact the results of the first trimester combined screening test. We conducted a retrospective cross-sectional study on singleton pregnancies achieved by embryo transfer of a single frozen-thawed blastocyst, comparing two different endometrial preparation protocols: natural cycle (n = 174) and hormone replacement therapy (HRT) (n = 122). The primary outcome was the risk of preeclampsia at the first trimester combined screening test. Secondary endpoints included variable reflecting fetal cardiac function (nuchal translucency and fetal heart rate), maternal adaptation (median arterial blood pressure-MAP and uterine arteries pulsatility index-UtA-PI), and placentation (pregnancy associated plasma protein A and placental growth factor). The risk of early preeclampsia was comparable in the two groups (38% vs. a 28%, p = 0.12). However, women in the natural cycle group showed lower fetal heart rate (159 [155-164] vs. 164 [158-168], p = 0.002) and higher UtA-PI (0.96 [0.74-1.18] vs. 0.72 [0.58-0.90], p < 0.001). The frequency of a screening test at high risk for aneuploidies was similar. The modality of transfer of frozen-thawed embryos is associated with changes in the variables reflecting maternal and fetal cardiovascular function.

The true natural cycle frozen embryo transfer - impact of patient and follicular phase characteristics on serum progesterone levels one day prior to warmed blastocyst transfer

BACKGROUND

In a true-natural cycle (t-NC), optimal progesterone (P4) output from the corpus luteum is crucial for establishing and maintaining an intrauterine pregnancy. In a previous retrospective study, low P4 levels (< 10 ng/mL) measured one day before warmed blastocyst transfer in t-NC were associated with significantly lower live-birth rates. In the current study, we aim to examine the relationship between patient, follicular-phase endocrine and ultrasonographic characteristics, and serum P4 levels one day prior to warmed blastocyst transfer in t-NC.

METHOD

178 consecutive women undergoing their first t-NC frozen embryo transfer (FET) between July 2017-August 2022 were included. Following serial ultrasonographic and endocrine monitoring, ovulation was documented by follicular collapse. Luteinized unruptured follicle (LUF) was diagnosed when there was no follicular collapse despite luteinizing-hormone surge (> 17 IU/L) and increased serum P4 (> 1.5 ng/mL). FET was scheduled on follicular collapse + 5 or LH surge + 6 in LUF cycles. Primary outcome was serum P4 on FET - 1.

RESULTS

Among the 178 patients, 86% (n = 153) experienced follicular collapse, while 14% (n = 25) had LUF. On FET-1, the median serum luteal P4 level was 12.9 ng/mL (IQR: 9.3-17.2), ranging from 1.8 to 34.4 ng/mL. Linear stepwise regression revealed a negative correlation between body mass index (BMI) and LUF, and a positive correlation between follicular phase peak-E2 and peak-P4 levels with P4 levels on FET-1. The ROC curve analyses to predict < 9.3 ng/mL (< 25th percentile) P4 levels on FET-1 day showed AUC of 0.70 (95%CI 0.61-0.79) for BMI (cut-off: 23.85 kg/m2), 0.71 (95%CI 0.61-0.80) for follicular phase peak-P4 levels (cut-off: 0.87 ng/mL), and 0.68 (95%CI 0.59-0.77) for follicular phase peak-E2 levels (cut-off: 290.5 pg/mL). Combining all four independent parameters yielded an AUC of 0.80 (95%CI 0.72-0.88). The adjusted-odds ratio for having < 9.3 ng/mL P4 levels on FET-1 day for patients with LUF compared to those with follicle collapse was 4.97 (95%CI 1.66-14.94).

CONCLUSION

The BMI, LUF, peak-E2, and peak-P4 levels are independent predictors of low serum P4 levels on FET-1 (< 25th percentile; <9.3 ng/ml) in t-NC FET cycles. Recognition of risk factors for low serum P4 on FET-1 may permit a personalized approach for LPS in t-NC FET to maximize reproductive outcomes.

Obstetric and neonatal outcomes after natural versus artificial cycle frozen embryo transfer and the role of luteal phase support: a systematic review and meta-analysis

BACKGROUND

The number of frozen embryo transfers (FET) has increased dramatically over the past decade. Based on current evidence, there is no difference in pregnancy rates when natural cycle FET (NC-FET) is compared to artificial cycle FET (AC-FET) in subfertile women. However, NC-FET seems to be associated with lower risk of adverse obstetric and neonatal outcomes compared with AC-FET cycles. Currently, there is no consensus about whether NC-FET needs to be combined with luteal phase support (LPS) or not. The question of how to prepare the endometrium for FET has now gained even more importance and taken the dimension of safety into account as it should not simply be reduced to the basic question of effectiveness.

OBJECTIVE AND RATIONALE

The objective of this project was to determine whether NC-FET, with or without LPS, decreases the risk of adverse obstetric and neonatal outcomes compared with AC-FET.

SEARCH METHODS

A systematic review and meta-analysis was carried out. A literature search was performed using the following databases: CINAHL, EMBASE, and MEDLINE from inception to 10 October 2022. Observational studies, including cohort studies, and registries comparing obstetric and neonatal outcomes between singleton pregnancies after NC-FET and those after AC-FET were sought. Risk of bias was assessed using the ROBINS-I tool. The quality of evidence was evaluated using the Grading of Recommendations Assessment, Development and Evaluation approach. We calculated pooled odds ratios (ORs), pooled risk differences (RDs), pooled adjusted ORs, and prevalence estimates with 95% CI using a random effect model, while heterogeneity was assessed by the I2.

OUTCOMES

The conducted search identified 2436 studies, 890 duplicates were removed and 1546 studies were screened. Thirty studies (NC-FET n = 56 445; AC-FET n = 57 231) were included, 19 of which used LPS in NC-FET. Birthweight was lower following NC-FET versus AC-FET (mean difference 26.35 g; 95% CI 11.61-41.08, I2 = 63%). Furthermore NC-FET compared to AC-FET resulted in a lower risk of large for gestational age (OR 0.88, 95% 0.83-0.94, I2 = 54%), macrosomia (OR 0.81; 95% CI 0.71-0.93, I2 = 68%), low birthweight (OR 0.81, 95% CI 0.77-0.85, I2 = 41%), early pregnancy loss (OR 0.73; 95% CI 0.61-0.86, I2 = 70%), preterm birth (OR 0.80; 95% CI 0.75-0.85, I2 = 20%), very preterm birth (OR 0.66, 95% CI 0.53-0.84, I2 = 0%), hypertensive disorders of pregnancy (OR 0.60, 95% CI 0.50-0.65, I2 = 61%), pre-eclampsia (OR 0.50; 95% CI 0.42-0.60, I2 = 44%), placenta previa (OR 0.84, 95% CI 0.73-0.97, I2 = 0%), and postpartum hemorrhage (OR 0.43; 95% CI 0.38-0.48, I2 = 53%). Stratified analyses on LPS use in NC-FET suggested that, compared to AC-FET, NC-FET with LPS decreased preterm birth risk, while NC-FET without LPS did not (OR 0.75, 95% CI 0.70-0.81). LPS use did not modify the other outcomes. Heterogeneity varied from low to high, while quality of the evidence was very low to moderate.

WIDER IMPLICATIONS

This study confirms that NC-FET decreases the risk of adverse obstetric and neonatal outcomes compared with AC-FET. We estimate that for each adverse outcome, use of NC-FET may prevent 4 to 22 cases per 1000 women. Consequently, NC-FET should be the preferred treatment in women with ovulatory cycles undergoing FET. Based on very low quality of evidence, the risk of preterm birth be decreased when LPS is used in NC-FET compared to AC-FET. However, because of many uncertainties-the major being the debate about efficacy of the use of LPS-future research is needed on efficacy and safety of LPS and no recommendation can be made about the use of LPS.

First-trimester serum antiphosphatidylserine antibodies serve as candidate biomarkers for predicting pregnancy-induced hypertension

OBJECTIVE

The aim of this study was to explore whether antiphosphatidylserine (aPS) antibodies play roles in the early prediction of pregnancy-induced hypertension (PIH).

METHODS

The serum levels of different isotypes of aPS antibodies were compared in women diagnosed with PIH (PIH group, n  = 30) and 1 : 1 matched normotensive controls (control group, n  = 30). All patients underwent frozen embryo transfer (FET) cycles, and all serum samples were collected during 11-13 weeks of gestation. Receiver operating characteristic (ROC) curves were drawn to analyze the predictive values of aPS antibodies for PIH.

RESULTS

The women who developed PIH after FET had higher serum optical density values (450 nm) of aPS immunoglobulin (Ig) A (1.31 ± 0.43 vs. 1.02 ± 0.51, P  = 0.022), aPS IgM (1.00 ± 0.34 vs. 0.87 ± 0.18, P  = 0.046), and aPS IgG (0.50 ± 0.12 vs. 0.34 ± 0.07, P  < 0.001) compared with the normotensive controls. The serum concentration of total IgG [48.29 ± 10.71 (g/dl) vs. 34.39 ± 11.62 (g/dl), P  < 0.001] was also higher in the PIH group compared with that in the control group. The aPS IgG alone [area under the curve (AUC): 0.913, 95% confidence interval (CI): 0.842-0.985, P  < 0.001] and the combined analysis of aPS IgA, aPS IgM, aPS IgG, and total IgG (AUC: 0.944, 95% CI: 0.888-1.000, P  < 0.001) had high predictive values for PIH.

CONCLUSION

Serum aPS autoantibody levels during the first trimester of pregnancy are positively associated with the development of PIH. Further validation is needed to clearly identify the distinct contributions and underlying mechanisms for diagnostic applications of aPS autoantibodies in PIH prediction.

Increased Risk of Preeclampsia with Assisted Reproductive Technologies

PURPOSE OF REVIEW

We summarized recent available data to assess the association between assisted reproductive technology (ART) and risk for preeclampsia.

RECENT FINDINGS

The majority of clinical studies supporting the association of preeclampsia and ART are retrospective. Published data from both clinical and pre-clinical studies suggest specific ART procedures may contribute to the increased risk, including in vitro embryo handling and development, hormone stimulation, transfer cycle types, and use of donor oocytes/embryos. Potential mechanisms include epigenetic aberrations leading to abnormal placentation, absence of factors secreted by the corpus luteum, and immunologic responses to allogenic gametes. There is an increased risk of preeclampsia following ART. Treatment plans that favor reduced preeclampsia risk should be considered for ART pregnancies. To make ART pregnancies safer, additional clinical and animal model studies are needed to elucidate the underpinnings of this risk association.

Comparison of the efficacy of subcutaneous versus vaginal progesterone using a rescue protocol in vitrified blastocyst transfer cycles

RESEARCH QUESTION

Does administration of subcutaneous (s.c.) progesterone support ongoing pregnancy rates (OPR) similar to vaginal progesterone using a rescue protocol in hormone replacement therapy frozen embryo transfer cycles?

DESIGN

Retrospective cohort study. Two sequential cohorts - vaginal progesterone gel (December 2019-October 2021; n=474) and s.c. progesterone (November 2021-November 2022; n=249) -were compared. Following oestrogen priming, s.c. progesterone 25 mg twice daily (b.d.) or vaginal progesterone gel 90 mg b.d. was administered. Serum progesterone was measured 1 day prior to warmed blastocyst transfer (i.e. day 5 of progesterone administration). In patients with serum progesterone concentrations <8.75 ng/ml, additional s.c. progesterone (rescue protocol; 25 mg) was provided.

RESULTS

In the vaginal progesterone gel group, 15.8% of patients had serum progesterone <8.75 ng/ml and received the rescue protocol, whereas no patients in the s.c. progesterone group received the rescue protocol. OPR, along with positive pregnancy and clinical pregnancy rates, were comparable between the s.c. progesterone group without the rescue protocol and the vaginal progesterone gel group with the rescue protocol. After the rescue protocol, the route of progesterone administration was not a significant predictor of ongoing pregnancy. The impact of different serum progesterone concentrations on reproductive outcomes was evaluated by percentile (<10th, 10-49th, 50-90th and >90th percentiles), taking the >90th percentile as the reference subgroup. In both the vaginal progesterone gel group and the s.c. progesterone group, all serum progesterone percentile subgroups had similar OPR.

CONCLUSIONS

Subcutaneous progesterone 25 mg b.d. secures serum progesterone >8.75 ng/ml, whereas additional exogenous progesterone (rescue protocol) was needed in 15.8% of patients who received vaginal progesterone. The s.c. and vaginal progesterone routes, with the rescue protocol if needed, yield comparable OPR.

Live birth after letrozole-stimulated cycles versus hormone replacement treatment cycles for the first frozen embryo transfer in women with polycystic ovary syndrome: protocol for a multicentre randomised controlled trial

INTRODUCTION

Hormone replacement treatment (HRT) is the most commonly used endometrial preparation protocol for frozen embryo transfer (FET) in patients with polycystic ovary syndrome (PCOS). However, studies have found that HRT may increase the risk of hypertensive disorders of pregnancy and some obstetric complications. Letrozole is a new first-line ovulation induction drug for PCOS and can effectively induce spontaneous ovulation by reducing oestrogen levels. However, letrozole is still rarely used in FET and has only been reported in a few studies in Asian populations. High-quality, well-powered randomised controlled trials (RCTs) comparing HRT and letrozole-stimulated protocols are lacking. The aim of this study is to compare the efficacy and safety of two protocols in patients with PCOS.

METHODS AND ANALYSIS

This is a multicentre, open-label RCT in four reproductive medical centres in China. In total, 1078 women with PCOS will be randomised (1:1) to the letrozole-stimulated or HRT group in their first FET cycle and their pregnancy and perinatal outcomes during this cycle will be followed up and analysed. The primary outcome is live birth. Secondary outcomes are cycle cancellation rate, biochemical pregnancy, clinical pregnancy, miscarriage, ectopic pregnancy, obstetric and perinatal complications, neonatal complications and birth weight.

ETHICS AND DISSEMINATION

Ethical approval was obtained from the Institutional Review Board of Reproductive and Genetic Hospital of CITIC-XIANGYA (LL-SC-2022-001). Written informed consent will be obtained from each participant. The findings will be disseminated through conference presentations and publication in peer-reviewed journals.

TRIAL REGISTRATION NUMBER

NCT05227391.

The influence of embryo stage on obstetric complications and perinatal outcomes following programmed compared to natural frozen-thawed embryo transfer cycles: a systematic review and meta-analysis

Objective

To investigate the effect of embryo stage at the time of transfer on obstetric and perinatal outcomes in programmed frozen-thawed embryo transfer (FET) versus natural FET cycles.

Design

Systematic review and meta-analysis.

Setting

Not applicable.

Patients

Women with programmed frozen-thawed embryo transfer (FET) and natural FET.

Interventions

The PubMed, MEDLINE, and EMBASE databases and the Cochrane Central Register of Controlled Trials (CCRT) were searched from 1983 to October 2022. Twenty-three observational studies were included.

Primary outcome measure

The primary outcomes were hypertensive disorders of pregnancy (HDPs), gestational hypertension and preeclampsia (PE). The secondary outcomes were gestational diabetes mellitus (GDM), placenta previa, postpartum haemorrhage (PPH), placental abruption, preterm premature rupture of membranes (PPROM), large for gestational age (LGA), small for gestational age (SGA), macrosomia, and preterm delivery (PTD).

Results

The risk of HDP (14 studies, odds ratio (OR) 2.17; 95% confidence interval (CI) 1.95-2.41; P<0.00001; I2 = 43%), gestational hypertension (11 studies, OR 1.38; 95% CI 1.15-1.66; P=0.0006; I2 = 19%), PE (12 studies, OR 2.09; 95% CI 1.88-2.32; P<0.00001; I2 = 0%), GDM (20 studies, OR 1.09; 95% CI 1.02-1.17; P=0.02; I2 = 8%), LGA (18 studies, OR 1.11; 95% CI 1.07-1.15; P<0.00001; I2 = 46%), macrosomia (12 studies, OR 1.15; 95% CI 1.07-1.24; P=0.0002; I2 = 31%), PTD (22 studies, OR 1.21; 95% CI 1.15-1.27; P<0.00001; I2 = 49%), placenta previa (17 studies, OR 1.2; 95% CI 1.02-1.41; P=0.03; I2 = 11%), PPROM (9 studies, OR 1.19; 95% CI 1.02-1.39; P=0.02; I2 = 40%), and PPH (12 studies, OR 2.27; 95% CI 2.02-2.55; P <0.00001; I2 = 55%) were increased in programmed FET cycles versus natural FET cycles with overall embryo transfer. Blastocyst transfer had a higher risk of HDP (6 studies, OR 2.48; 95% CI 2.12-2.91; P<0.00001; I2 = 39%), gestational hypertension (5 studies, OR 1.87; 95% CI 1.27-2.75; P=0.002; I2 = 25%), PE (6 studies, OR 2.23; 95% CI 1.93-2.56; P<0.00001; I2 = 0%), GDM (10 studies, OR 1.13; 95% CI 1.04-1.23; P=0.005; I2 = 39%), LGA (6 studies, OR 1.14; 95% CI 1.07-1.21; P<0.0001; I2 = 9%), macrosomia (4 studies, OR 1.15; 95% CI 1.05-1.26; P<0.002; I2 = 68%), PTD (9 studies, OR 1.43; 95% CI 1.31-1.57; P<0.00001; I2 = 22%), PPH (6 studies, OR 1.92; 95% CI 1.46-2.51; P<0.00001; I2 = 55%), and PPROM (4 studies, OR 1.45; 95% CI 1.14-1.83; P=0.002; I2 = 46%) in programmed FET cycles than in natural FET cycles. Cleavage-stage embryo transfers revealed no difference in HDPs (1 study, OR 0.81; 95% CI 0.32-2.02; P=0.65; I2 not applicable), gestational hypertension (2 studies, OR 0.85; 95% CI 0.48-1.51; P=0.59; I2 = 0%), PE (1 study, OR 1.19; 95% CI 0.58-2.42; P=0.64; I2not applicable), GDM (3 study, OR 0.79; 95% CI 0.52-1.20; P=0.27; I2 = 21%), LGA (1 study, OR 1.15; 95% CI 0.62-2.11; P=0.66; I2not applicable), macrosomia (1 study, OR 1.22; 95% CI 0.54-2.77; P=0.64; I2 not applicable), PTD (2 studies, OR 1.05; 95% CI 0.74-1.49; P=0.79; I2 = 0%), PPH (1 study, OR 1.49; 95% CI 0.85-2.62; P=0.17; I2not applicable), or PPROM (2 studies, OR 0.74; 95% CI 0.46-1.21; P=0.23; I2 = 0%) between programmed FET cycles and natural FET cycles.

Conclusions

The risks of HDPs, gestational hypertension, PE, GDM, LGA, macrosomia, SGA, PTD, placenta previa, PPROM, and PPH were increased in programmed FET cycles versus natural FET cycles with overall embryo transfer and blastocyst transfer, but the risks were not clear for cleavage-stage embryo transfer.

Higher risk of pre-eclampsia and other vascular disorders with artificial cycle for frozen-thawed embryo transfer compared to ovulatory cycle or to fresh embryo transfer following in vitro fertilization

Background

Risks of maternal morbidity are known to be reduced in pregnancies resulting from frozen embryo transfer (FET) compared to fresh-embryo transfer (fresh-ET), except for the risk of pre-eclampsia, reported to be higher in FET pregnancies compared to fresh-ET or natural conception. Few studies have compared the risk of maternal vascular morbidities according to endometrial preparation for FET, either with ovulatory cycle (OC-FET) or artificial cycle (AC-FET). Furthermore, maternal pre-eclampsia could be associated with subsequent vascular disorders in the offspring.

Methods

A 2013-2018 French nationwide cohort study comparing maternal vascular morbidities in 3 groups of single pregnancies was conducted: FET with either OC or AC preparation, and fresh-ET. Data were extracted from the French National Health System database. Results were adjusted for maternal characteristics and infertility (age, parity, smoking, obesity, history of diabetes or hypertension, endometriosis, polycystic ovary syndrome and premature ovarian insufficiency).

Results

A total of 68025 single deliveries were included: fresh-ET (n=48152), OC-FET (n=9500), AC-FET (n=10373). The risk of pre-eclampsia was higher in AC-FET compared to OC-FET and fresh-ET groups in univariate analysis (5.3% vs. 2.3% and 2.4%, respectively, P<0.0001). In multivariate analysis the risk was significantly higher in AC-FET compared to fresh-ET: aOR=2.43 [2.18-2.70], P<0.0001). Similar results were observed for the risk of other vascular disorders in univariate analysis (4.7% vs. 3.4% and 3.3%, respectively, P=0.0002) and in multivariate analysis (AC-FET compared to fresh-ET: aOR=1.50 [1.36-1.67], P<0.0001). In multivariate analysis, the risk of pre-eclampsia and other vascular disorders were comparable in OC-FET and fresh-ET: aOR=1.01 [0.87-1.17, P= 0.91 and aOR=1.00 [0.89-1.13], P=0.97, respectively).Within the group of FET, the risks of pre-eclampsia and other vascular disorders in multivariate analysis were higher in AC-FET compared to OC-FET (aOR=2.43 [2.18-2.70], P<0.0001 and aOR=1.5 [1.36-1.67], P<0.0001, respectively).

Conclusion

This nationwide register-based cohort study highlights the possibly deleterious role of prolonged doses of exogenous estrogen-progesterone supplementation on gestational vascular pathologies and the protective role of the corpus luteum present in OC-FET for their prevention. Since OC-FET has been demonstrated not to strain the chances of pregnancy, OC preparation should be advocated as first-line preparation in FET as often as possible in ovulatory women.

Ovulatory-cycle frozen embryo transfer: spontaneous or triggered ovulation and the impact of LH elevation at hCG triggering

The effect of the luteinizing hormone (LH) elevation before the human chorionic gonadotropin (hCG) trigger in ovulatory frozen-thawed embryo transfer (Ovu-FET) cycles has not been determined. We aimed to investigate whether triggering ovulation in Ovu-FET cycles affects the live birth rate (LBR), and the contribution of elevated LH at the time of hCG trigger. This retrospective study included Ovu-FET cycles performed in our center from August 2016 to April 2021. Modified Ovu-FET (hCG trigger) and true Ovu-FET (without hCG trigger) were compared. The modified group was divided according to whether hCG was administered, before or after LH increased to > 15 IU/L and was twice the baseline value. The modified (n = 100) and true (n = 246) Ovu-FET groups and both subgroups of the modified Ovu-FET, those who were triggered before (n = 67) or after (n = 33) LH elevation, had comparable characteristics at baseline. Comparison of true vs. modified Ovu-FET outcomes revealed similar LBR (35.4% vs. 32.0%; P = 0.62), respectively. LBR were similar between the modified Ovu-FET subgroups regardless of the hCG trigger timing (31.3% before vs. 33.3% after LH elevation; P = 0.84). In conclusion, LBR of Ovu-FET were not affected by hCG trigger or whether LH was elevated at the time of hCG trigger. These results add reassurance regarding hCG triggering even after LH elevation.

Is artificial endometrial preparation more associated with early-onset or late-onset preeclampsia after frozen embryo transfer?

PURPOSE

To explore whether the risks of early- or late-onset preeclampsia vary among frozen embryo transfer (FET) with different regimens for endometrial preparation and fresh embryo transfer (FreET).

METHODS

We retrospectively included a total of 24129 women who achieved singleton delivery during their first cycles of in vitro fertilization (IVF) between January 2012 and March 2020. The risks of early- and late-onset preeclampsia after FET with endometrial preparation by natural ovulation cycles (FET-NC) or by artificial cycles (FET-AC) were compared to that after FreET.

RESULTS

After adjustment via multivariable logistic regression, the total risk of preeclampsia was higher in the FET-AC group compared to the FreET group [2.2% vs. 0.9%; adjusted odds ratio (aOR): 2.00; 95% confidence interval (CI): 1.45-2.76] and FET-NC group (2.2% vs. 0.9%; aOR: 2.17; 95% CI: 1.59-2.96).When stratified by the gestational age at delivery based on < 34 weeks or ≥ 34 weeks, the risk of late-onset preeclampsia remained higher in the FET-AC group than that in the and FreET group (1.8% vs. 0.6%; aOR: 2.56; 95% CI: 1.83-3.58) and the FET-NC group (1.8% vs. 0.6%; aOR: 2.63; 95% CI: 1.86-3.73). We did not find a statistically significant difference in the risk of early-onset preeclampsia among the three groups.

CONCLUSIONS

An artificial regimen for endometrial preparation was more associated with an increased risk of late-onset preeclampsia after FET. Given that FET-AC is widely used in clinical practice, the potential maternal risk factors for late-onset preeclampsia when using the FET-AC regimen should be further explored, considering the maternal origin of late-onset preeclampsia.

The future of frozen-thawed embryo transfer in hormone replacement therapy cycles

PURPOSE OF REVIEW

This review focuses on the efficacy of letrozole stimulated frozen-thawed embryo transfer (FET) compared to hormone replacement therapy (HRT) FET in women with polycystic ovarian syndrome (PCOS) and/or oligo-anovulation. Further, obstetric and perinatal risks in HRT FET are summarized.

RECENT FINDINGS

The presence of a corpus luteum seems to reduce the risk of pregnancy-related hypertension and preeclampsia after FET. As a natural cycle (NC) FET is not an option for women with oligo-/amenorrhea these women may benefit from FET with mild stimulation compared to HRT FET. The intention of mild stimulation in anovulatory women is to induce (mono) ovulation to mimic the endocrine profiles of the natural cycle and the early pregnancy after natural conception. Mild stimulation by letrozole is patient friendly and cheap compared to gonadotropin stimulated FET and has been increasingly used in recent years. Although the quality of evidence is low, the pregnancy outcomes after letrozole FET seems similar or even better compared to HRT FET in women with PCOS and/or oligo-anovulation.

SUMMARY

Natural and modified NC FET should be used whenever possible to mitigate adverse obstetric and perinatal outcomes after HRT FET. For anovulatory women, whenever ovulation can be induced, we advocate the use of mild stimulation FET to create a corpus luteum awaiting results from RCTs limited to oligo-anovulatory women.

Comparing endometrial preparation methods in frozen embryo transfers - Does a previous live birth make a difference?

RESEARCH QUESTION

Does the outcome of a medicated or natural endometrial preparation for a frozen cycle differ if a patient has previously experienced a failed fresh cycle?

DESIGN

Retrospective matched case-controlled study to investigate frozen embryo transfer (FET) outcomes in women undergone medicated or natural endometrial preparation, with adjustment to the history of previous live birth. 878 frozen cycles were included for analysis, over a period of 2 years.

RESULTS

After adjusting for the number of embryos transferred, endometrial thickness and the number of previous embryo transfers, there was no difference in live birth rate (LBR) between medicated-FET and natural-FET groups regardless of the previous fertility outcome (p = 0.08).

CONCLUSIONS

A previous live birth does not affect the outcome of a subsequent frozen cycle, regardless of whether medicated- or natural endometrial preparation is used.

Impact of different endometrial preparation protocols before frozen embryo transfer on pregnancy outcomes: a review

The use of frozen embryo transfer cycles has exponentially increased in the last few years. Optimization of endometrial preparation protocols before frozen embryo transfer is mandatory to further improve pregnancy outcomes. This review will focus on the existing literature with regard to the different available endometrial preparation protocols and their impact on pregnancy outcomes. More specifically, we will focus on programmed, natural, and stimulated frozen embryo transfer cycles. The studies performed on this topic are generally of low quality, and only a few well-performed randomized controlled trials have been published. To date, no strong evidence is available to support the use of 1 preparation method over another in terms of pregnancy outcomes. However, robust data have shown a clearly protective effect of natural frozen embryo transfer cycles against long-term obstetric complications, mainly hypertensive disorders of pregnancy and large for gestational age infants. The introduction of individualized luteal phase support in different endometrial preparation protocols is actually gaining a lot of attention and requires further investigation.

Ovulation induction regimens are associated with a higher rate of livebirth after frozen single-blastocyst transfer among women with polycystic ovary syndrome

BACKGROUND

Hormone replacement therapy (HRT) regimen was suggested to be associated with a decreased rate of livebirth and a higher risk of hypertensive disorders of pregnancy (HDP) after frozen cleavage stage embryo transfer in women with polycystic ovary syndrome (PCOS). With the dramatically increased use of elective single embryo transfer, there is great need to explore the impacts of different endometrial preparation regimens on frozen single-blastocyst transfer in women with PCOS.

METHODS

In this study, a total of 3941 women who diagnosed with PCOS and underwent single-blastocyst transfer during their first cycles of frozen embryo transfer (FET) between March 2012 and December 2020 were included. We retrospectively compared the pregnancy and neonatal outcomes after frozen single-blastocyst transfer with endometrial preparation by HRT regimen (n = 3540), ovulation induction by human menopausal gonadotropin (hMG) regimen (n = 226), and ovulation induction by letrozole regimen (n = 175).

RESULTS

After adjustment for confounders with multivariable logistic regression, the hMG regimen group [(58.4% vs. 49.6%; adjusted odds ratio (aOR): 1.43; 95% confidence interval (CI): 1.09-1.89)] and letrozole regimen group (58.9% vs. 49.6%; aOR: 1.42; 95% CI: 1.04-1.93) were associated with a higher rate of livebirth (primary outcome), compared with the group with HRT regimen. As to the secondary outcomes, the rate of pregnancy loss in the hMG regimen group (22.8% vs. 30.3%; aOR: 0.69; 95% CI: 0.48-1.00) and letrozole regimen group (16.9% vs. 30.3%; aOR: 0.48; 95% CI: 0.30-0.78) was also lower than that in the HRT regimen group. The pregnancy outcomes between the hMG regimen group and the letrozole regimen group were similar. We did not observe significant difference in the incidences of maternal and neonatal complications among these three groups.

CONCLUSION

Ovulation induction regimen with letrozole or hMG for endometrial preparation was associated with a higher livebirth rate and a lower pregnancy loss rate in frozen single-blastocyst transfer cycles among women with PCOS.