Does low-dose aspirin improve pregnancy rate in women undergoing frozen-thawed embryo transfer cycle? A pilot double-blind, randomized placebo-controlled trial

Impact of low-dose aspirin therapy initiation timing on pregnancy outcomes after frozen-thawed blastocyst transfer

Clinical effects of low-dose aspirin (LDA) on embryo implantation still remains controversial; therefore, we investigated the appropriate timing for starting LDA in frozen-thawed embryo transfer (ET) cycles. A cross-sectional study was conducted on 885 infertile women who underwent thrombophilia screening between 2020 and 2023. We recruited first frozen-thawed blastocyst transfer cycles in 553 consecutive women aged < 40 years. LDA was started on the day of ET from 2020 to 2021 in 79 women (day 0 group) and at 5 days after ET from 2021 to 2023 in 215 women (day 5 group). We also recruited 259 consecutive women who underwent first frozen-thawed blastocyst transfer without LDA treatment from 2020 to 2023 (control). We compared pregnancy outcomes after frozen-thawed ET between the three groups. In results, clinical pregnancy and livebirth rates after frozen-thawed ET in the day 0 group were significantly lower than those in the other two groups (clinical pregnancy rates: 57.5 %, 40.5 %, and 61.4 %, p = 0.005 and livebirth rates: 48.6 %, 34.2 %, and 54.0 %, p = 0.01 in the control, day 0, and day 5 groups, respectively). Multivariable logistic regression analysis showed that livebirth rate in the day 0 group was significantly lower than those in the other groups (odds ratio [OR]: 0.54, 95 % confidential interval [CI]: 0.31 -0.95); however, no significant difference in livebirth rates was found between the day 5 and control groups (OR: 1.13, 95 %CI: 0.70 -1.80). Starting LDA prior to implantation may decrease pregnancy and livebirth rates after frozen-thawed blastocyst transfer.

Body mass index modified the effectiveness of low dose aspirin treatment on frozen-thawed embryo transfer outcome: a propensity score-matched study

Background

Low-dose aspirin is one of the widely used adjuvants in assisted reproductive technologies with the hope of improving the live birth rate. However, the studies regarding its effects are conflicting. The study aimed to investigate the association between aspirin administration and live birth following frozen-thawed embryo transfer (FET) in patients with different body mass index (BMI).

Methods

A retrospective cohort study was performed on 11,993 patients receiving FET treatments. 644 of which received a low-dose aspirin (100 mg/day) during endometrial preparation until 10 weeks after transfer. Propensity score matching was performed to avoid selection biases and potential confounders.

Results

The clinical pregnancy rate and live birth rate were similar before matching (54.4% versus 55.4%, RR: 1.02, 95%CI: 0.95-1.09, and 46.3 versus 47.8, RR: 1.03, 95%CI: 0.95-1.12 respectively). A weak association in favor of aspirin administration was found in the matched cohort (49.5% versus 55.4%, RR: 1.12, 95%CI: 1.01-1.24, and 41.9% versus 47.8%, RR: 1.14, 95%CI: 1.01-1.29 respectively). However, when stratified the patients with WHO BMI criteria, a significant increase in live birth rate associated with aspirin treatment was found only in patients with low BMI (<18.5 kg/m2) in either unmatched (46.4% versus 59.8%, RR:1.29, 95%CI:1.07-1.55) or matched cohort (44% versus 59.8%, RR: 1.36, 95%CI: 1.01-1.83) but not in patients with higher BMI categories. With the interaction analysis, less association between aspirin and live birth appeared in patients with normal BMI (Ratio of OR:0.49, 95%CI: 0.29-0.81) and high BMI (Ratio of OR:0.57, 95%CI: 0.27-1.2) compared with patients with low BMI.

Conclusion

BMI may be considered when evaluating aspirin's effect in FET cycles.

Unveiling the potential effects of acetylsalicylic acid: insights into regeneration in endometrial stem cells

BACKGROUND

Although acetylsalicylic acid has been widely used for decades to treat and prevent various diseases, its potential effects on endometrial receptivity and subsequent pregnancy rates are still controversial due to conflicting data: many reports have shown positive effects of acetylsalicylic acid, whereas others have found that it has no effect. Furthermore, the direct effects of acetylsalicylic acid on various functions of normal endometrial cells, especially endometrial stem cells, and their underlying molecular mechanisms have not yet been proven. Recently, studies have revealed that a reduced number of active stem/progenitor cells within endometrial tissue limits cyclic endometrial regeneration and subsequently decreases pregnancy success rates, suggesting that endometrial stem cells play a critical role in endometrial regeneration and subsequent endometrial receptivity.

METHODS

We assessed whether aspirin treatment can inhibit various endometrial stem cell functions related to regenerative capacity, such as self-renewal, migration, pluripotency/stemness, and differentiation capacity, in vitro. Next, we evaluated whether SERPINB2 regulates the effects of aspirin on endometrial stem cell functions by depleting SERPINB2 expression with specific shRNA targeting SERPINB2. To further investigate whether aspirin also inhibits various endometrial stem cell functions in vivo, aspirin was administered daily to mice through intraperitoneal (i.p.) injection for 7 days.

RESULTS

In addition to its previously identified roles, to the best of our knowledge, we found for the first time that acetylsalicylic acid directly inhibits various human endometrial stem cell functions related to regenerative capacity (i.e., self-renewal, migration, differentiation, and capacity) through its novel target gene SERPINB2 in vitro. Acetylsalicylic acid exerts its function by suppressing well-known prosurvival pathways, such as Akt and/or ERK1/2 signaling, through a SERPINB2 signaling cascade. Moreover, we also found that acetylsalicylic acid markedly inhibits regenerative capacity-related functions in endometrial stem cells within tissue.

CONCLUSIONS

We have found that acetylsalicylic acid has diverse effects on various endometrial stem cell functions related to regenerative capacity. Our findings are a critical step toward the development of more effective therapeutic strategies to increase the chances of successful pregnancy. Video Abstract.

Immunomodulation for unexplained recurrent implantation failure: where are we now?

In brief

Immune dysfunction may contribute to or cause recurrent implantation failure. This article summarizes normal and pathologic immune responses at implantation and critically appraises currently used immunomodulatory therapies.

Abstract

Recurrent implantation failure (RIF) may be defined as the absence of pregnancy despite the transfer of ≥3 good-quality blastocysts and is unexplained in up to 50% of cases. There are currently no effective treatments for patients with unexplained RIF. Since the maternal immune system is intricately involved in mediating endometrial receptivity and embryo implantation, both insufficient and excessive endometrial inflammatory responses during the window of implantation are proposed to lead to implantation failure. Recent strategies to improve conception rates in RIF patients have focused on modulating maternal immune responses at implantation, through either promoting or suppressing inflammation. Unfortunately, there are no validated, readily available diagnostic tests to confirm immune-mediated RIF. As such, immune therapies are often started empirically without robust evidence as to their efficacy. Like other chronic diseases, patient selection for immunomodulatory therapy is crucial, and personalized medicine for RIF patients is emerging. As the literature on the subject is heterogenous and rapidly evolving, we aim to summarize the potential efficacy, mechanisms of actions and side effects of select therapies for the practicing clinician.

Evidence for the effectiveness of immunologic therapies in women with subfertility and/or undergoing assisted reproduction

Implantation is a critical step in the establishment of a successful pregnancy, depending on a complex immune-endocrine dialogue between the developing embryo and maternal endometrium. Research suggests that altered immunity in the maternal decidua results in implantation impairment and failure. Immunomodulatory drugs have, thus, been widely used in assisted conception to aid embryo implantation, despite an absence of consensus on their effectiveness and safety. We conducted a systematic review and meta-analysis of interventional studies investigating the use of immunomodulators in women undergoing assisted reproduction. Evidence was uncertain of an effect for most of the included interventions, owing to heterogeneous findings and a paucity of high-quality studies. For certain patient subgroups, however, the use of specific immunomodulatory therapies may offer some benefit. There is a need for further large randomized controlled trials to corroborate these findings.

Effect of intrauterine perfusion of granular leukocyte-colony stimulating factor on the outcome of frozen embryo transfer

BACKGROUND

Treatment of thin endometrium with granular leukocyte-colony stimulating factor (G-CSF) remains controversial.

AIM

To investigate the effect of G-CSF on the outcome of frozen embryo transfer in patients with thin endometrium.

METHODS

A retrospective propensity score matching (PSM) study was performed to assess patients administered frozen embryo transfer at the Reproductive Medicine Center of the Affiliated Drum Tower Hospital of Nanjing University Medical School, in 2012-2018. The patients were divided into G-CSF intrauterine perfusion (G-CSF) and non-G-CSF groups, and clinical pregnancy, implantation, ectopic pregnancy, and early abortion rates between the two groups were compared.

RESULTS

Before PSM, 372 cycles were enrolled, including 242 and 130 cycles in the G-CSF and non-G-CSF groups, respectively. Age (34.23 ± 5.76 vs 32.99 ± 5.59 years; P = 0.047) and the blastula/cleavage stage embryo ratio (0.68 vs 0.37; P = 0.011) were significantly elevated in the G-CSF group compared with the non-G-CSF group; however, clinical pregnancy (46.28% vs 51.54%; P = 0.371) and embryo implantation (35.21% vs 35.65%; P = 0.910) rates were similar in both groups. After PSM by age and blastula/cleavage stage embryo ratio, 244 cycles were included (122 cases each in the G-CSF and non-G-CSF groups). The clinical pregnancy (50.82 % vs 48.36%; P = 0.701) and embryo implantation (37.38% vs 34.11%; P = 0.480) remained similar in both groups.

CONCLUSION

Intrauterine infusion of G-CSF does not improve the clinical outcome of frozen embryo transfer in patients with thin endometrium.

Aspirin for Endometrial Preparation in Patients Undergoing IVF: A Systematic Review and Meta-analysis

OBJECTIVE

To investigate the effect of aspirin on IVF success rates when used as an adjuvant treatment for endometrial preparation.

DATA SOURCES

Relevant publications were comprehensively selected from PubMed, MEDLINE, Embase, and the Cochrane Central Register of Controlled Trials (CENTRAL) up to November 15, 2020.

STUDY SELECTION

Randomized controlled trials (RCTs) and retrospective cohort studies that used aspirin as an adjuvant treatment for endometrial preparation and reported subsequent pregnancy outcomes were included. Studies were excluded if aspirin was used before and/or during ovarian stimulation.

DATA EXTRACTION AND SYNTHESIS

This systematic review and meta-analysis included a total of 7 studies. Risk of bias assessment was based on the methodology and categories listed in the Cochrane Handbook for the RCTs and the Newcastle-Ottawa scale for the retrospective studies. The primary outcome was live birth rate. Summary measures were reported as odds ratios (ORs) with 95% confidence intervals (CIs). There was significant evidence that aspirin for endometrial preparation improved live birth rates (OR  1.52; 95% CI   1.15-2.00). No effect was noted for clinical pregnancy rates (OR  1.37; 95% CI   1.00-1.87); however, aspirin was associated with improved pregnancy rates in a subgroup analysis of patients receiving oocyte donation (OR 2.53; 95% CI 1.30-4.92) and in the sensitivity analysis (OR 1.3; 95% CI   1.02-1.66). No effect of aspirin was found for implantation or miscarriage rates (OR 1.31; 95% CI  0.51-3.36 and OR 0.41; 95% CI  0.02-7.42, respectively).

CONCLUSION

These findings support a beneficial effect of aspirin for endometrial preparation on IVF success rates, mainly live birth rates, outside the context of ovarian stimulation. However, this evidence is based on poor quality data and needs to be confirmed with high-quality RCTs.

Routine ketorolac at oocyte retrieval decreases postoperative narcotic use by more than 50

Objective

To study the impact of routine ketorolac administration during oocyte retrieval on the proportion of patients who require postoperative narcotics for analgesia.

Design

Retrospective cohort study.

Setting

Single, university-affiliated infertility clinic.

Patient(s)

All women undergoing oocyte retrieval between July and November 2016 (non-ketorolac group [NKG]; n = 826) and April-August 2017 (ketorolac group, KG; n = 1780).

Intervention(s)

A single 30 mg intravenous dose of ketorolac was administered after the oocyte retrieval procedure.

Main outcome measure(s)

The number of patients who required postoperative narcotic analgesia, postoperative complication rate, and fresh embryo transfer pregnancy outcomes were examined.

Result(s)

In the KG, we found a significant decrease in the patients who required narcotics after oocyte retrieval compared with the NKG (12% KG vs. 25.5% NKG). We found no significant change in the clinical pregnancy rate (CPR) resulting from fresh embryo transfer after our intervention (NKG CPR 32.6%, KG CPR 32.4%). Furthermore, there was no increase in postoperative bleeding complications in the KG.

Conclusion(s)

Routine use of ketorolac at the time of oocyte retrieval may decrease the rate of postoperative opioid use without adversely impacting pregnancy and complication rates.

Aspirin and heparin in the treatment of recurrent spontaneous abortion associated with antiphospholipid antibody syndrome: A systematic review and meta-analysis

The present study aimed to review relevant, randomized, controlled trials in order to determine the effects of aspirin and heparin treatment on recurrent spontaneous abortion (RSA) in women with antiphospholipid syndrome (APS). Previous relevant studies were identified using PubMed, Cochrane, Embase, CNKI, VANFUN and VIP by retrieving appropriate key words. Additionally, key relevant sources in the literature were reviewed and articles published before May 2019 were included. The 22 selected studies included 1,515 patients in the treatment group and 1,531 patients in the control group. These previous studies showed that heparin and aspirin significantly improved live birth rate when compared with treatments using intravenous immunoglobulin, aspirin alone or aspirin combined with prednisone. Moreover, heparin and aspirin greatly increased the birth weight compared with placebo and improved vaginal delivery relative to intravenous immunoglobulin. The gestational age at birth was significantly higher in the heparin and aspirin group compared with the placebo group and the incidence of intrauterine growth restriction was lower in the heparin and aspirin group compared with the placebo group. Furthermore, heparin and aspirin markedly reduced the incidence of miscarriage compared with the aspirin group and the placebo group, and the incidence of pre-eclampsia was lower in the heparin and aspirin group than the placebo group. Thus, heparin and aspirin could be further examined for the treatment of RSA in women with APS.

Endometrial preparation for women undergoing embryo transfer with frozen embryos or embryos derived from donor oocytes

BACKGROUND

A frozen embryo transfer (FET) cycle is when one or more embryos (frozen during a previous treatment cycle) are thawed and transferred to the uterus. Some women undergo fresh embryo transfer (ET) cycles with embryos derived from donated oocytes. In both situations, the endometrium is primed with oestrogen and progestogen in different doses and routes of administration.

OBJECTIVES

To evaluate the most effective endometrial preparation for women undergoing transfer with frozen embryos or embryos from donor oocytes with regard to the subsequent live birth rate (LBR).

SEARCH METHODS

The Cochrane Gynaecology and Fertility Group trials register, CENTRAL, MEDLINE, Embase, PsycINFO, LILACS, trials registers and abstracts of reproductive societies' meetings were searched in June 2020 together with reference checking and contact with study authors and experts in the field to identify additional studies.

SELECTION CRITERIA

Randomised controlled trials (RCTs) evaluating endometrial preparation in women undergoing fresh donor cycles and frozen embryo transfers.

DATA COLLECTION AND ANALYSIS

We used standard methodological procedures recommended by Cochrane. We analysed all available interventions versus placebo, no treatment, or between each other. The primary review outcome was live birth rate. Secondary outcomes were clinical and multiple pregnancy, miscarriage, cycle cancellation, endometrial thickness and adverse effects.

MAIN RESULTS

Thirty-one RCTs (5426 women) were included. Evidence was moderate to very low-quality: the main limitations were serious risk of bias due to poor reporting of methods, and serious imprecision. Stimulated versus programmed cycle We are uncertain whether a letrozole-stimulated cycle compared to a programmed cycle, for endometrial preparation, improves LBR (odds ratio (OR) 1.26, 95% confidence interval (CI) 0.49 to 3.26; 100 participants; one study; very low-quality evidence). Stimulating with follicle stimulating hormone (FSH), letrozole or clomiphene citrate may improve clinical pregnancy rate (CPR) (OR 1.63, 95% CI 1.12 to 2.38; 656 participants; five studies; I² = 11%; low-quality evidence). We are uncertain if they reduce miscarriage rate (MR) (OR 0.79, 95% CI 0.36 to 1.71; 355 participants; three studies; I² = 0%; very low-quality evidence). Endometrial thickness (ET) may be reduced with clomiphene citrate (mean difference(MD) -1.04, 95% CI -1.59 to -0.49; 92 participants; one study; low-quality evidence). Other outcomes were not reported. Natural versus programmed cycle We are uncertain of the effect from a natural versus programmed cycle for LBR (OR 0.97, 95% CI 0.74 to 1.28; 1285 participants; four studies; I² = 0%; very low-quality evidence) and CPR (OR 0.79, 95% CI 0.62 to 1.01; 1249 participants; five studies; I² = 60%; very low-quality evidence), while a natural cycle probably reduces the cycle cancellation rate (CCR) (OR 0.60, 95% CI 0.44 to 0.82; 734 participants; one study; moderate-quality evidence). We are uncertain of the effect on MR and ET. No study reported other outcomes. Transdermal versus oral oestrogens From low-quality evidence we are uncertain of the effect transdermal compared to oral oestrogens has on CPR (OR 0.86, 95% CI 0.59 to 1.25; 504 participants; three studies; I² = 58%) or MR (OR 0.55, 95% CI 0.27 to 1.09; 414 participants; two studies; I² = 0%). Other outcomes were not reported. Day of starting administration of progestogen When doing a fresh ET using donated oocytes in a synchronised cycle starting progestogen on the day of oocyte pick-up (OPU) or the day after OPU, in comparison with recipients that start progestogen the day prior to OPU, probably increases the CPR (OR 1.87, 95% CI 1.13 to 3.08; 282 participants; one study, moderate-quality evidence). We are uncertain of the effect on multiple pregnancy rate (MPR) or MR. It probably reduces the CCR (OR 0.28, 95% CI 0.11 to 0.74; 282 participants; one study; moderate-quality evidence). No study reported other outcomes. Gonadotropin-releasing hormone (GnRH) agonist versus control A cycle with GnRH agonist compared to without may improve LBR (OR 2.62, 95% CI 1.19 to 5.78; 234 participants; one study; low-quality evidence). From low-quality evidence we are uncertain of the effect on CPR (OR 1.08, 95% CI 0.82 to 1.43; 1289 participants; eight studies; I² = 20%), MR (OR 0.85, 95% CI 0.36 to 2.00; 828 participants; four studies; I² = 0%), CCR (OR 0.49, 95% CI 0.21 to 1.17; 530 participants; two studies; I² = 0%) and ET (MD -0.08, 95% CI -0.33 to 0.16; 697 participants; four studies; I² = 4%). No study reported other outcomes. Among different GnRH agonists From very low-quality evidence we are uncertain if cycles among different GnRH agonists improves CPR or MR. No study reported other outcomes. GnRH agonists versus GnRH antagonists GnRH antagonists compared to agonists probably improves CPR (OR 0.62, 95% CI 0.42 to 0.90; 473 participants; one study; moderate-quality evidence). We are uncertain of the effect on MR and MPR. No study reported other outcomes. Aspirin versus control From very low-quality evidence we are uncertain whether a cycle with aspirin versus without improves LBR, CPR, or ET. Steroids versus control From very low-quality evidence we are uncertain whether a cycle with steroids compared to without improves LBR, CPR or MR. No study reported other outcomes.

AUTHORS' CONCLUSIONS

There is insufficient evidence on the use of any particular intervention for endometrial preparation in women undergoing fresh donor cycles and frozen embryo transfers. In frozen embryo transfers, low-quality evidence showed that clinical pregnancy rates may be improved in a stimulated cycle compared to a programmed one, and we are uncertain of the effect when comparing a programmed cycle to a natural cycle. Cycle cancellation rates are probably reduced in a natural cycle. Although administering a GnRH agonist, compared to without, may improve live birth rates, clinical pregnancy rates will probably be improved in a GnRH antagonist cycle over an agonist cycle. In fresh synchronised oocyte donor cycles, the clinical pregnancy rate is probably improved and cycle cancellation rates are probably reduced when starting progestogen the day of or day after donor oocyte retrieval. Adequately powered studies are needed to evaluate each treatment more accurately.

The effect of low-dose aspirin on the pregnancy rate in frozen-thawed embryo transfer cycles: A randomized clinical trial

Background

The results of previous studies on the effect of low-dose aspirin in frozen-thawed embryo transfer (FET) cycles are limited and controversial.

Objective

To evaluate the effect of low-dose aspirin on the clinical pregnancy in the FET cycles.

Materials and Methods

This study was performed as a randomized clinical trial from May 2018 to February 2019; 128 women who were candidates for the FET were randomly assigned to two groups receiving either 80 mg oral aspirin (n = 64) or no treatment. The primary outcome was clinical pregnancy rate and secondary outcome measures were the implantation rate, miscarriage rate, and endometrial thickness.

Results

The endometrial thickness was lower in patients who received aspirin in comparison to the control group. There were statistically significant differences between the two groups (p = 0.018). Chemical and clinical pregnancy rates and abortion rate was similar in the two groups and there was no statistically significant difference.

Conclusion

The administration of aspirin in FET cycles had no positive effect on the implantation and the chemical and clinical pregnancy rates, which is in accordance with current Cochrane review that does not recommend aspirin administration as a routine in assisted reproductive technology cycles.