Low-dose aspirin in non-tubal IVF patients with previous failed conception: a prospective randomized double-blind placebo-controlled trial

New advances in the treatment of thin endometrium

Thin endometrium (TE) is defined as a mid-luteal endometrial thickness ≤7mm. TE can affect endometrial tolerance, leading to lower embryo implantation rates and clinical pregnancy rates, and is also associated with impaired outcomes from assisted reproductive treatment. Herein, we systematically review TE causes, mechanisms, and treatments. TE pathogenesis has multiple causes, with the endometrium becoming thinner with age under hormonal influence. In addition, uterine cavity factors are important, as the inflammatory environment may affect expressions of certain genes thereby inhibiting endometrial stromal cell proliferation and promoting apoptosis. Long-term oral contraceptive use or the use of ovulation-promoting drugs are also definite factors contributing to endometrial thinning. Other patients have primary factors, for which the clinical etiology remains unknown. The main therapeutic strategies available for TE are pharmacological (including hormonal and vasoactive drugs), regenerative medicine, intrauterine infusion of growth factor-granulocyte colony-stimulating factor, autologous platelet-rich plasma, and complementary alternative therapies (including traditional Chinese herbal medicine and acupuncture). However, the associated mechanisms of action are currently unclear. Clinical scholars have proposed various approaches to improve treatment outcomes in patients with TE, and are exploring the principles of efficacy, offering potentials for novel treatments. It is hoped that this will improve TE tolerance, increase embryo implantation rates, and help more couples with infertility with effective treatments.

Low-dose aspirin therapy for the prevention of preeclampsia: time to reconsider our recommendations?

The American College of Obstetricians and Gynecologists recommends initiation of 81 mg of aspirin daily for women at risk of preeclampsia between 12 and 28 weeks' gestation, optimally before 16 weeks, with continuation until delivery. The World Health Organization recommends that 75 mg of aspirin should be initiated before 20 weeks of gestation for women at high risk of preeclampsia. Both the Royal College of Obstetricians and Gynaecologists and the National Institute of Health and Care Excellence quality statement on "Antenatal Assessment of Pre-eclampsia Risk" request that healthcare providers prescribe low-dose aspirin to pregnant women at increased risk of preeclampsia daily from 12 weeks of gestation. The Royal College of Obstetricians and Gynaecologists recommends 150 mg of aspirin daily, and the National Institute of Health and Care Excellence guidelines suggest risk stratification with a dosage of 75 mg for those at moderate risk of preeclampsia and 150 mg for those at high risk of preeclampsia. The International Federation of Gynecology and Obstetrics initiative on preeclampsia recommends 150 mg of aspirin to be initiated at 11 to 14+6 week's gestation and also proposes that 2 tablets of 81 mg is an acceptable alternative. Review of the available evidence suggests that both the dosage and timing of aspirin initiation is key to its effectiveness at reducing the risk of preeclampsia. Doses of >100 mg of aspirin daily initiated before 16 weeks' gestation seem to be most effective at reducing the risk of preeclampsia and thus dosages recommended by most major societies and organizations may not be effective. Randomized control trials examining 81 mg vs 162 mg of aspirin daily for the prevention of preeclampsia are required to assess the safety and efficacy of aspirin dosages available in the United States.

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.

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.

Efficacy of therapies and interventions for repeated embryo implantation failure: a systematic review and meta-analysis

The aim of the present systematic review and meta-analysis was to assess the effect of the different therapeutic options for repeated embryo implantation failure (RIF) on a subsequent IVF cycle outcome. Twenty-two RCTs and nineteen observational studies were included. Pooling of results showed a beneficial effect of intrauterine PBMC infusion on both CPR (RR 2.18; 95% CI 1.58-3.00; p < 0.00001; OR 2.03; 95% CI 1.22-3.36; p = 0.006) and LBR (RR 2.41; 95% CI 1.40-4.16; p = 0.002; OR 3.73; 95% CI 1.13-12.29; p = 0.03), of subcutaneous G-CSF administration on CPR (RR 2.29; 95% CI 1.58-3.31; p < 0.0001) and of intrauterine PRP infusion on CPR (RR 2.45; 95% CI 1.55-3.86; p = 0.0001). Observational studies also demonstrated a positive effect of IVIG and intrauterine hCG infusion on both CPR and LBR and of atosiban on CPR. Studies investigating intrauterine G-CSF infusion, LMWH, intravenous intralipid, hysteroscopy, blastocyst-stage ET, ZIFT, PGT-A and AH failed to observe an impact on IVF outcome. The quality of the evidence that emerged from RCTs focused on intrauterine PBMC infusion and subcutaneous G-CSF administration was moderate. For all other therapies/interventions it varied from low to very low. In conclusion, intrauterine PBMC infusion and subcutaneous G-CSF administration are the most promising therapeutic options for RIF. However, further well conducted RCTs are necessary before their introduction into clinical practice.

Analgesic use at ovulation and implantation and human fertility

BACKGROUND

Studies investigating the effects of pain-relieving medication use on conceiving a pregnancy have shown conflicting results. Furthermore, no previous study has examined medication use around ovulation or implantation and the associations with the probability of conception, fecundability.

OBJECTIVE

The objective of the study was to explore the association between fecundability and analgesic use in 3 different menstrual cycle windows (preovulation, periovulation, and implantation) as well as across the entire menstrual cycle.

STUDY DESIGN

We analyzed data from a prospective cohort study of women between 30 and 44 years of age who were trying to conceive naturally from 2008 through 2015. Using daily diaries, medication usage was classified as acetaminophen, aspirin, or nonaspirin nonsteroidal antiinflammatory drug during 4 time periods of interest (preovulatory, periovulatory, and implantation) as well as the overall nonmenstrual bleeding days of the cycle. Menstrual cycles during the prospective attempt to become pregnant were enumerated using daily diary menstrual bleeding information. Conception was defined as a positive home pregnancy test. Discrete time fecundability models were used to estimate the fecundability ratio and 95% confidence interval in each of the 4 time windows of interest and for each pain reliever (aspirin use, nonaspirin nonsteroidal antiinflammatory drug use, acetaminophen) compared with no medication use after adjustment for several covariates including age, race, education, body mass index, alcohol and caffeine use, frequency of intercourse, and a history of migraines or uterine fibroids.

RESULTS

Medication use was infrequent in the 858 women and 2366 cycles in this analysis. Use of nonaspirin nonsteroidal antiinflammatory drugs or acetaminophen was not associated with fecundability in any of the time windows of interest. Although the sample size was small, aspirin use during the implantation window was associated with increased fecundability (adjusted fecundability ratio [confidence interval]: 2.05 [1.23-3.41]). This association remained when limiting the analysis to cycles with minimal missing data or when adjusting for gravidity. None of the other medications were associated with fecundability.

CONCLUSION

Aspirin use around implantation was associated with increased fecundability. These results expand previous literature to suggest the following: (1) implantation may be an important target for the effects of aspirin on conception and (2) aspirin may be beneficial, regardless of pregnancy loss history. These observations should be tested with a clinical trial.

Does low-dose aspirin initiated before 11 weeks' gestation reduce the rate of preeclampsia?

OBJECTIVE DATA

Preconception or early administration of low-dose aspirin might improve endometrial growth, placental vascularization, and organogenesis. Most studies have evaluated the potential benefit of preconception or early administration of low-dose aspirin in women with a history of recurrent pregnancy loss, women who have undergone in vitro fertilization, or women with thrombophilia or antiphospholipid syndrome. These women are at an increased risk of placenta-associated complications of pregnancy, including preeclampsia, preterm delivery, and fetal growth restriction.

STUDY OUTCOMES

We performed a systematic review and meta-analysis to evaluate the effect of low-dose aspirin initiated at <11 weeks' gestation on the risk of preeclampsia, gestational hypertension, or any hypertensive disorder of pregnancy. Secondary outcomes included preterm delivery at <37 weeks' gestation and fetal growth restriction.

STUDY APPRAISAL AND SYNTHESIS METHODS

We searched in MEDLINE via PubMed, EMBASE, Cochrane Central Register of Controlled Trials (CENTRAL), ClinicalTrials.gov, and the World Health Organization International Clinical Trials Registry Platform from 1985 to November 2018. Entry criteria were randomized controlled trials evaluating the effect of aspirin administered at <11 weeks' gestation in preventing preeclampsia and/or hypertensive disorders in pregnancy or improving pregnancy outcomes in women with recurrent miscarriage as compared with placebo or no treatment and outcome data available or provided by authors for >85% of the study population. Relative risks with 95% confidence intervals were calculated for each study and pooled for global analysis as the effect measure. We assessed statistical heterogeneity in each meta-analysis using the χ² statistics, I², and Tau². Heterogeneity was considered substantial if an I² was greater than 50% and either the Tau² was greater than zero or there was a low P value (<0.10) in the χ² test for heterogeneity. Random-effects meta-analysis, weighted by the size of the studies, was performed to produce an overall summary on aspirin effect for each outcome. Sensitivity analysis by sequential omission of each individual study and by fixed-effects model was performed. Publication bias was not assessed because of the small number of included studies. Statistical analysis was performed using Stata release 14.0 (StataCorp).

RESULTS

The entry criteria were fulfilled by 8 randomized controlled trials on a combined total of 1426 participants. Low-dose aspirin initiated at <11 weeks' gestation was associated with a nonsignificant reduction in the risk of preeclampsia (relative risk, 0.52; 95% confidence interval, 0.23-1.17, P = .115), gestational hypertension (relative risk, 0.49; 95% confidence interval, 0.20-1.21; P = .121), and any hypertensive disorder of pregnancy (relative risk, 0.59; 95% confidence interval, 0.33-1.04, P = .067). Early administration of low-dose aspirin reduced the risk of preterm delivery (relative risk, 0.52; 95% confidence interval, 0.27-0.97, P = .040) but had no impact on the risk of fetal growth restriction (relative risk, 1.10; 95% confidence interval, 0.58-2.07, P = .775). Except for preterm delivery and any hypertensive disorder of pregnancy, sensitivity analysis demonstrated similar observations, therefore confirming the robustness of the analysis.

CONCLUSION

The administration of low-dose aspirin at <11 weeks' gestation in women at high risk does not decrease the risk of preeclampsia, gestational hypertension, any hypertensive disorder of pregnancy, and fetal growth restriction. However, it might reduce the risk of preterm delivery. Larger randomized controlled trials will be required to substantiate the findings.

Antiplatelet agents for preventing pre-eclampsia and its complications

BACKGROUND

Pre-eclampsia is associated with deficient intravascular production of prostacyclin, a vasodilator, and excessive production of thromboxane, a vasoconstrictor and stimulant of platelet aggregation. These observations led to the hypotheses that antiplatelet agents, low-dose aspirin in particular, might prevent or delay development of pre-eclampsia.

OBJECTIVES

To assess the effectiveness and safety of antiplatelet agents, such as aspirin and dipyridamole, when given to women at risk of developing pre-eclampsia.

SEARCH METHODS

For this update, we searched Cochrane Pregnancy and Childbirth's Trials Register, ClinicalTrials.gov, the WHO International Clinical Trials Registry Platform (ICTRP) (30 March 2018), and reference lists of retrieved studies. We updated the search in September 2019 and added the results to the awaiting classification section of the review.

SELECTION CRITERIA

All randomised trials comparing antiplatelet agents with either placebo or no antiplatelet agent were included. Studies only published in abstract format were eligible for inclusion if sufficient information was available. We would have included cluster-randomised trials in the analyses along with individually-randomised trials, if any had been identified in our search strategy. Quasi-random studies were excluded. Participants were pregnant women at risk of developing pre-eclampsia. Interventions were administration of an antiplatelet agent (such as low-dose aspirin or dipyridamole), comparisons were either placebo or no antiplatelet.

DATA COLLECTION AND ANALYSIS

Two review authors assessed trials for inclusion and extracted data independently. For binary outcomes, we calculated risk ratio (RR) and its 95% confidence interval (CI), on an intention-to-treat basis. For this update we incorporated individual participant data (IPD) from trials with this available, alongside aggregate data (AD) from trials where it was not, in order to enable reliable subgroup analyses and inclusion of two key new outcomes. We assessed risk of bias for included studies and created a 'Summary of findings' table using GRADE.

MAIN RESULTS

Seventy-seven trials (40,249 women, and their babies) were included, although three trials (relating to 233 women) did not contribute data to the meta-analysis. Nine of the trials contributing data were large (> 1000 women recruited), accounting for 80% of women recruited. Although the trials took place in a wide range of countries, all of the nine large trials involved only women in high-income and/or upper middle-income countries. IPD were available for 36 trials (34,514 women), including all but one of the large trials. Low-dose aspirin alone was the intervention in all the large trials, and most trials overall. Dose in the large trials was 50 mg (1 trial, 1106 women), 60 mg (5 trials, 22,322 women), 75mg (1 trial, 3697 women) 100 mg (1 trial, 3294 women) and 150 mg (1 trial, 1776 women). Most studies were either low risk of bias or unclear risk of bias; and the large trials were all low risk of bas. Antiplatelet agents versus placebo/no treatment The use of antiplatelet agents reduced the risk of proteinuric pre-eclampsia by 18% (36,716 women, 60 trials, RR 0.82, 95% CI 0.77 to 0.88; high-quality evidence), number needed to treat for one women to benefit (NNTB) 61 (95% CI 45 to 92). There was a small (9%) reduction in the RR for preterm birth <37 weeks (35,212 women, 47 trials; RR 0.91, 95% CI 0.87 to 0.95, high-quality evidence), NNTB 61 (95% CI 42 to 114), and a 14% reduction infetal deaths, neonatal deaths or death before hospital discharge (35,391 babies, 52 trials; RR 0.85, 95% CI 0.76 to 0.95; high-quality evidence), NNTB 197 (95% CI 115 to 681). Antiplatelet agents slightly reduced the risk of small-for-gestational age babies (35,761 babies, 50 trials; RR 0.84, 95% CI 0.76 to 0.92; high-quality evidence), NNTB 146 (95% CI 90 to 386), and pregnancies with serious adverse outcome (a composite outcome including maternal death, baby death, pre-eclampsia, small-for-gestational age, and preterm birth) (RR 0.90, 95% CI 0.85 to 0.96; 17,382 women; 13 trials, high-quality evidence), NNTB 54 (95% CI 34 to 132). Antiplatelet agents probably slightly increase postpartum haemorrhage > 500 mL (23,769 women, 19 trials; RR 1.06, 95% CI 1.00 to 1.12; moderate-quality evidence due to clinical heterogeneity), and they probably marginally increase the risk of placental abruption, although for this outcome the evidence was downgraded due to a wide confidence interval including the possibility of no effect (30,775 women; 29 trials; RR 1.21, 95% CI 0.95 to 1.54; moderate-quality evidence). Data from two large trials which assessed children at aged 18 months (including results from over 5000 children), did not identify clear differences in development between the two groups.

AUTHORS' CONCLUSIONS

Administering low-dose aspirin to pregnant women led to small-to-moderate benefits, including reductions in pre-eclampsia (16 fewer per 1000 women treated), preterm birth (16 fewer per 1000 treated), the baby being born small-for-gestational age (seven fewer per 1000 treated) and fetal or neonatal death (five fewer per 1000 treated). Overall, administering antiplatelet agents to 1000 women led to 20 fewer pregnancies with serious adverse outcomes. The quality of evidence for all these outcomes was high. Aspirin probably slightly increased the risk of postpartum haemorrhage of more than 500 mL, however, the quality of evidence for this outcome was downgraded to moderate, due to concerns of clinical heterogeneity in measurements of blood loss. Antiplatelet agents probably marginally increase placental abruption, but the quality of the evidence was downgraded to moderate due to low event numbers and thus wide 95% CI. Overall, antiplatelet agents improved outcomes, and at these doses appear to be safe. Identifying women who are most likely to respond to low-dose aspirin would improve targeting of treatment. As almost all the women in this review were recruited to the trials after 12 weeks' gestation, it is unclear whether starting treatment before 12 weeks' would have additional benefits without any increase in adverse effects. While there was some indication that higher doses of aspirin would be more effective, further studies would be warranted to examine this.

The role of immunotherapy in in vitro fertilization: a guideline

Adjuvant immunotherapy treatments in in vitro fertilization (IVF) aim to improve the outcome of assisted reproductive technology (ART) in both the general ART population as well as subgroups such as patients with recurrent miscarriage or implantation failure. The purpose of this guideline is to evaluate the role of immunomodulating therapy in ART. Unfortunately, many of the evaluated therapies lack robust evidence from well-designed adequately powered randomized controlled trials to support their use. Immunotherapies reviewed in the present document are either not associated with improved live-birth outcome in IVF or have been insufficiently studied to make definitive recommendations.

Efficacy evaluation of low-dose aspirin in IVF/ICSI patients evidence from 13 RCTs: A systematic review and meta-analysis

BACKGROUND

We conducted a systematic review and meta-analysis of existing literature to evaluate the different outcomes of low-dose aspirin on patients undergoing in vitro fertilization (IVF)/intracytoplasmic sperm injection (ICSI), including clinical pregnancy rate, implantation rate, live birth rate, miscarriage rate, fertilization rate, number of oocytes retrieved, and so forth.

METHODS

Electronic databases including PubMed, MEDLINE, and Embase were searched between 1997 and March 2016 to identity eligible studies. The following comparisons between treatment groups were included: aspirin versus placebo; aspirin versus control group; aspirin versus aspirin + prednisolone + control.

RESULTS

Thirteen randomized controlled trials which included 3104 participants were selected. There were no significant differences in implantation rate (RR = 1.15; 95% CI = 0.78-1.70), live birth rate (RR = 1.06; 95% CI = 0.93-1.21), miscarriage rate (RR = 1.28; 95% CI = 0.93-1.77), fertilization rate (RR = 0.91; 95% CI = 0.75-1.11), and endometrial thickness (WMD = 0.15; 95% CI = -0.38-0.67). But the research showed that aspirin treatment may improve the clinical pregnancy rate (RR = 1.16; 95% CI = 1.04-1.28) compared to placebo or no treatment, and reduce the number of oocytes retrieved (WMD = -0.68; 95% CI = -0.91-0.46).

CONCLUSIONS

Our findings suggest that low-dose aspirin may improve the pregnancy rate in IVF/ICSI, with the recommended clinical use dose of 100 mg/day. Considering the limitation of included studies, further well-designed large-scaled RCTs are necessary to clarify whether aspirin may improve assisted reproduction outcomes in IVF/ICSI patients.

The Effects of Aspirin in Gestation and Reproduction (EAGeR) Trial: A Story of Discovery

Human reproduction is an inefficient process. There are several drivers of complications along the path to and during pregnancy, one of which is inflammation. Treatments to mitigate the deleterious effects of aberrant inflammation with something inexpensive and widely available like aspirin could have dramatic global impact. The Effects of Aspirin in Gestation and Reproduction (EAGeR) trial enrolled women aged 18 to 40 years with one to two prior pregnancy losses and no diagnosis of infertility. Patients were randomized to either low-dose aspirin or placebo. Here, we review the collective findings of the EAGeR trial to date and discuss several important lessons learned from the unique data resulting from this groundbreaking trial. Findings reported from this trial provide significant advances in the understanding of aspirin’s potential mechanisms in modulating reproductive processes and the role of inflammation in these processes. This review describes the collective findings of the EAGeR trial in the context of the existing literature regarding aspirin and inflammation in reproduction to inform relevant next steps in fertility and obstetric research, as well as potential implications for clinical care.

Preconception use of pain-relievers and time-to-pregnancy: a prospective cohort study

STUDY QUESTION

To what extent is preconception use of pain-relieving medication associated with female fecundability?

SUMMARY ANSWER

Women who used naproxen or opioids had slightly lower fecundability than women who did not use any pain-relieving medications; use of acetaminophen, aspirin and ibuprofen was not appreciably associated with fecundability.

WHAT IS KNOWN ALREADY

Over-the-counter pain-relieving medications are commonly used by women of reproductive age in the USA. Studies investigating the effects of pain-relieving medication use on ovulation, implantation and fecundability have shown conflicting results.

STUDY DESIGN, SIZE, DURATION

We analyzed data from an internet-based prospective cohort study of 2573 female pregnancy planners aged 21-45 years from the USA and Canada. Participants were enrolled and followed from June 2013 through September 2015. Participants completed a baseline questionnaire and bimonthly follow-up questionnaires until a reported pregnancy or for 12 months, whichever occurred first. Over 80% of participants completed at least one follow-up questionnaire.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Use of pain-relieving medication during the past month was assessed at baseline and on each follow-up questionnaire. Medications were categorized according to type (acetaminophen, aspirin, ibuprofen, naproxen and opioids) and total monthly dose. Self-reported pregnancy was assessed at each follow-up. Multivariable-adjusted fecundability ratios (FRs) and 95% CI were calculated using proportional probabilities regression. Models were adjusted for demographic, lifestyle and anthropometric factors; reproductive history; gynecologic morbidity; and indications for use of pain medications. Models were also run with and without adjustment for parity. After restricting to women with 6 or fewer months of attempt time at study entry, 1763 were included in the analyses.

MAIN RESULTS AND THE ROLE OF CHANCE

At baseline, 1279 (73%) women reported using ≥1 pain-relieving medications in the previous month. When compared with non-use of pain-relieving medications, FRs for use of naproxen and opioids at baseline were 0.78 (95% CI: 0.64-0.97) and 0.81 (95% CI: 0.60-1.10), respectively. A dose-response relation was observed between naproxen use and fecundability; FRs for use of <1500 and ≥1500 mg of naproxen were 0.85 (95% CI: 0.68-1.07) and 0.58 (95% CI: 0.36-0.94), respectively. Small numbers (n = 74) precluded the examination of opioid use by dose. Overall, there was little evidence of an association between fecundability and acetaminophen (FR 1.04, 95% CI: 0.92-1.18), aspirin (FR 1.00, 95% CI: 0.80-1.25), or ibuprofen (FR 1.00, 95% CI: 0.89-1.11). Similar results were observed when exposure information was updated over time.

LIMITATIONS, REASONS FOR CAUTION

Numbers of opioid users were small. Information collected on reason for use of pain medications was not specific to each type of pain medication. Therefore, we cannot rule out confounding by indication as an explanation of these results.

WIDER IMPLICATIONS OF THE FINDINGS

Use of naproxen and opioids was associated with a small reduction in fecundability, but there was little association between other pain-relieving medications and fecundability.

STUDY FUNDING/COMPETING INTERESTS

This study was supported through funds provided by National Institute of Child Health and Human Development, National Institute of Health (R21 HD072326, T32 HD052458). The authors have no conflicts of interest to disclose.

TRIAL REGISTRATION NUMBER

Not applicable.

Aspirin for in vitro fertilisation

BACKGROUND

Aspirin is used with the aim of optimising the chance of live birth in women undergoing assisted reproductive technology (ART), despite inconsistent evidence of its efficacy and safety (in terms of intraoperative bleeding during oocyte retrieval and risk of miscarriage). The most appropriate time to commence aspirin therapy and the length of treatment required are also still to be determined. This is the second update of the review first published in 2007.

OBJECTIVES

To evaluate the effectiveness and safety of aspirin in women undergoing ART.

SEARCH METHODS

We searched the Cochrane Gynaecology and Fertility Group Trials Register, Cochrane Central Register of Controlled Trials (CENTRAL; 2016, Issue 4) in the Cochrane Library (searched 9 May 2016); the databases MEDLINE (1946 to 9 May 2016) and Embase (1974 to 9 May 2016); and trial registers (ClinicalTrials.gov and the World Health Organization International Clinical Trials Registry Platform search portal). We also examined the reference lists of all known primary studies and review articles, citation lists of relevant publications and abstracts of major scientific meetings, combined with the Cochrane Gynaecology and Fertility Group's search strategy.

SELECTION CRITERIA

Randomised controlled trials on aspirin for women undergoing ART.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed trial eligibility and risk of bias and extracted the data. The primary review outcome was live birth. Secondary outcomes included clinical pregnancy, ongoing pregnancy, multiple pregnancy, miscarriage, and other complications associated with IVF/ICSI or with pregnancy and birth. We combined data to calculate risk ratios (RRs) (for dichotomous data) and mean differences (MDs) (for continuous data) and 95% confidence intervals (CIs). Statistical heterogeneity was assessed using the I² statistic. We assessed the overall quality of the evidence for the main comparisons using GRADE methods.

MAIN RESULTS

The search identified 13 trials as eligible for inclusion in the review, including a total of 2653 participants with a mean age of 35 years. Ten studies used a dose of 100 mg and three used 80 mg of aspirin per day. In most of them, aspirin was commenced immediately at the start of down-regulation, while the duration of treatment varied widely. Eight studies provided a placebo for the control group.There was no evidence of a difference between the aspirin group and the group receiving no treatment or placebo in rates of live birth (RR 0.91, 95% CI 0.72 to 1.15, 3 RCTs, n = 1053, I² = 15%, moderate-quality evidence). In addition, clinical pregnancy rates were also similar for the two groups (RR 1.03, 95% CI 0.91 to 1.17, 10 RCTs, n = 2142, I² = 27%, moderate-quality evidence); sensitivity analysis, excluding studies at high risk of bias, did not change the effect estimate. There was no evidence of a difference between groups in terms of multiple pregnancy as confirmed by ultrasound (RR 0.67, 95% CI 0.37 to 1.25, 2 RCTs, n = 656, I² = 0%, low-quality evidence), miscarriage (RR 1.10, 95% CI 0.68 to 1.77, 5 RCTs, n = 1497, I² = 0%, low-quality evidence), ectopic pregnancy (RR 1.86, 95% CI 0.75 to 4.63, 3 RCTs, n = 1135, I² = 0%, very low quality evidence) or vaginal bleeding (RR 1.01, 95% CI 0.14 to 7.13, 1 RCT, n = 487, very low quality evidence). Data were lacking on other adverse effects.The overall quality of the evidence ranged from very low to moderate; limitations were poor reporting of study methods and suspected publication bias.

AUTHORS' CONCLUSIONS

Currently there is no evidence in favour of routine use of aspirin in order to improve pregnancy rates for a general IVF population. This is based on available data from randomised controlled trials, where there is currently no evidence of an effect of aspirin on women undergoing ART, as there is no single outcome measure demonstrating a benefit with its use. Furthermore, current evidence does not exclude the possibility of adverse effects.

Heme oxygenase and the immune system in normal and pathological pregnancies

Normal pregnancy is an immunotolerant state. Many factors, including environmental, socioeconomic, genetic, and immunologic changes by infection and/or other causes of inflammation, may contribute to inter-individual differences resulting in a normal or pathologic pregnancy. In particular, imbalances in the immune system can cause many pregnancy-related diseases, such as infertility, abortions, pre-eclampsia, and preterm labor, which result in maternal/fetal death, prematurity, or small-for-gestational age newborns. New findings imply that myeloid regulatory cells and regulatory T cells (Tregs) may mediate immunotolerance during normal pregnancy. Effector T cells (Teffs) have, in contrast, been implicated to cause adverse pregnancy outcomes. Furthermore, feto-maternal tolerance affects the developing fetus. It has been shown that the Treg/Teff balance affects litter size and adoptive transfer of pregnancy-induced Tregs can prevent fetal rejection in the mouse. Heme oxygenase-1 (HO-1) has a protective role in many conditions through its anti-inflammatory, anti-apoptotic, antioxidative, and anti-proliferative actions. HO-1 is highly expressed in the placenta and plays a role in angiogenesis and placental vascular development and in regulating vascular tone in pregnancy. In addition, HO-1 is a major regulator of immune homeostasis by mediating crosstalk between innate and adaptive immune systems. Moreover, HO-1 can inhibit inflammation-induced phenotypic maturation of immune effector cells and pro-inflammatory cytokine secretion and promote anti-inflammatory cytokine production. HO-1 may also be associated with T-cell activation and can limit immune-based tissue injury by promoting Treg suppression of effector responses. Thus, HO-1 and its byproducts may protect against pregnancy complications by its immunomodulatory effects, and the regulation of HO-1 or its downstream effects has the potential to prevent or treat pregnancy complications and prematurity.

ART and uterine pathology: how relevant is the maternal side for implantation?

BACKGROUND

Assisted reproduction technology (ART) has become a standard treatment for infertile couples. Increased success rates obtained over the years have resulted primarily from improved embryo quality, but implantation rates still remain lower than expected. The uterus, an important player in implantation, has been frequently neglected. While a number of uterine pathologies have been associated with decreased natural fertility, less information exists regarding the impact of these pathologies in ART. This report reviews the evidence to help clinicians advise ART patients.

METHODS

An electronic search of PubMed and EMBASE was performed to identify articles in the English, French or Spanish language published until May 2014 which addressed uterine pathology and ART. Data from natural conception were used only in the absence of data from ART. Studies were classified in decreasing categories: RCTs, prospective controlled trials, prospective non-controlled trials, retrospective studies and experimental studies. Studies included in lower categories were only used if insufficient evidence was available. Pooled data were obtained from systematic reviews with meta-analyses when available. The summary of the evidence for the different outcomes and the degree of the recommendation for interventions were based on the GRADE (Grading of Recommendations Assessment, Development and Evaluation) statement recommendations.

RESULTS

There is strong evidence that surrogacy is effective for uterine agenesia. For the remaining pathologies, however, there is very little evidence that the established treatments improve outcomes, or that these pathologies have a negative effect on ART. In the presence of an apparently normal uterus, assessing endometrial receptivity (ER) is the goal; however diagnostic tests are still under development.

CONCLUSIONS

The real effect of different uterine/endometrial integrity pathologies on ART is not known. Moreover, currently proposed treatments are not based on solid evidence, and little can be done to assess ER in normal or abnormal conditions. No strong recommendations can be given based on the published experience, bringing an urgent need for well-designed studies. In this context, we propose algorithms to study the uterus in ART.

Implantation in assisted reproduction: a look at endometrial receptivity

Implantation failure in assisted reproduction is thought to be mainly due to impaired uterine receptivity. With normal uterine anatomy, changes in endocrine profile during ovarian stimulation and medical conditions of the mother (i.e. thrombophilia and abnormal immunological response) could result in a non-receptive endometrium. High oestradiol concentrations during ovarian stimulation lead to premature progesterone elevation, causing endometrial advancement and hampering implantation, which can be overcome by a freeze-all approach and embryo transfer in natural cycles or by milder stimulation protocols. Patients with recurrent implantation failure (RIF) should be tested for inherited and acquired thrombophilias. Each patient should be individually assessed and counselled regarding therapy with low-molecular-weight heparin (LMWH). Empirical treatment with LMWH, aspirin or corticosteroids is not effective for women with RIF who have negative thrombophilic tests. If thrombophilic tests are normal, patients should be tested for immunological causes. If human leukocyte antigen dissimilarity is proven, treatment with intravenous immunoglobulin might be beneficial. Preliminary observational studies using intralipid infusion in the presence of increased natural killer cytotoxic activity are interesting but the proposed rationale is controversial and randomized controlled trials are needed. Hysteroscopy and/or endometrial scratching in the cycle preceding ovarian stimulation should become standard for patients with RIF.

Aspirin and heparin as adjuvants during IVF do not improve live birth rates in unexplained implantation failure

This study tested the hypothesis that using aspirin and/or heparin as adjuvants in IVF improves the treatment outcome. This retrospective cohort-control study recruited 234 consecutive subjects aged ≤ 44 years who had previously had one or more unsuccessful IVF cycle. All underwent IVF using conventional protocols. The study group received aspirin and/or heparin post embryo transfer until the day of pregnancy test or until 12 weeks of pregnancy. The control group did not receive adjuvant treatment. The outcome measures were live birth, clinical pregnancy and miscarriage rates. The outcomes were compared by chi-squared test and relative-risk analysis. Analysis was performed in 206 subjects. There was no statistically significant difference in the live birth rate (35.0%, 36/103 versus 47.6%, 49/103), clinical pregnancy rate (40.8%, 42/103 versus 53.4%, 55/103) and miscarriage rate (14.3%, 6/42 versus 10.9%, 6/55) between the study group and the control group. The data in this study show that low-dose aspirin and/or heparin as adjuvant therapies during IVF do not improve live birth rates in an unselected group of subfertile women who have previously had one or more unexplained implantation failure following IVF.

Low-dose aspirin for in vitro fertilization or intracytoplasmic sperm injection: a systematic review and a meta-analysis of the literature

BACKGROUND

It was hypothesized that low-dose aspirin could improve implantation rates in subsequent pregnancies in women undergoing in vitro fertilization (IVF)/intracytoplasmic sperm injection (ICSI). Previous studies have shown inconclusive results or focused on surrogate endpoints. We therefore conducted a systematic review and meta-analysis of the literature investigating the effect of low-dose aspirin on hard outcomes, including live birth rate, pregnancy rate and miscarriage.

METHODS

MEDLINE and EMBASE databases were searched up to November 2011. Randomized controlled trials comparing low-dose aspirin with placebo/no treatment in IVF/ICSI women were included. Pooled odds ratios (ORs) and 95%confidence intervals (CIs) were calculated.

RESULTS

Seventeen studies with 6403 patients were included. The use of aspirin did not improve live birth pregnancy rate compared with placebo or no treatment (1.08; 95% CI, 0.90, 1.29). Pregnancy rates were significantly increased in patients randomized to low-dose aspirin (OR, 1.19; 95% CI, 1.01, 1.39), but miscarriage rates were not (OR, 1.18; 95% CI, 0.82, 1.68). Results of sensitivity analyses including high-quality studies did not show statistically significant differences in all considered endpoints.

CONCLUSIONS

The results of this study do not show a substantial efficacy of aspirin inwomen undergoing IVF/ICSI and do not support the use of low-dose aspirin to improve the success of IVF/ICSI in terms of pregnancy outcomes. Further high-quality studies evaluating the possible efficacy of aspirin in selected groups of patients are warranted.

Aspirin for in vitro fertilisation

BACKGROUND

Aspirin is used to improve the outcome in women undergoing in vitro fertilisation despite inconsistent evidence of its efficacy. The most appropriate time to commence aspirin therapy and the length of treatment required are also still to be determined. This is an update of the review first published in 2007.

OBJECTIVES

To determine the effectiveness and safety of aspirin for improving the outcome of in vitro fertilisation and intracytoplasmic sperm injection treatment cycles.

SEARCH STRATEGY

We searched the Cochrane Menstrual Disorders and Subfertility Group Trials Register, Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library January 2011), MEDLINE (1966 to January 2011) and EMBASE (1980 to January 2011) databases. We used the research terms: "(aspirin OR acetylsalicylic acid) AND (in-vitro fertilisation OR intracytoplasmic sperm injection)", combined with the Cochrane Menstrual Disorders and Subfertility Group's search strategy, in order to identify randomised controlled trials on aspirin for women undergoing in vitro fertilisation.

SELECTION CRITERIA

Randomised controlled trials.

DATA COLLECTION AND ANALYSIS

Two authors independently selected studies to include in the review, extracted data and assessed trial quality.

MAIN RESULTS

The searches identified 13 trials which were eligible for inclusion in the review, including a total of 2653 participants. No significant differences were found between the treatment and control groups for any of the outcomes assessed. No significant differences were found in the meta-analysis of studies investigating the effect of aspirin compared with control on live birth rate (RR 0.91, 95% CI 0.72 to 1.15; three studies and 1053 participants), clinical pregnancy rate (RR 1.03, 95% CI 0.91 to 1.17; 10 studies and 2142 participants), ectopic and miscarriage rates (RR 1.86, 95% CI 0.75 to 4.63; RR 1.10, 95% CI 0.68 to 1.77) respectively (three and five studies involving 1135 and 1497 participants).

AUTHORS' CONCLUSIONS

Use of aspirin for women undergoing in vitro fertilisation cannot be recommended due to lack of evidence from the current trial data. Adequately powered trials are needed. It was proposed in the initial version of this review that a sample size of 350 women in each group would be required in order to demonstrate a 10% improvement from the use of aspirin, with 80% power at the 5% significance level. Until such evidence is available, this treatment can not be recommended.

[Thrombosis and assisted reproductive techniques (ART)]

Assisted reproductive techniques (ART) concern procedures designed to increase fertility of couples: artificial insemination, in vitro fertilization (IVF), either classical or after intracytoplasmic sperm injection (ICSI), transfer of frozen embryos, or gamete intrafallopian transfer. Their use has greatly increased these last years. They may be associated with severe ovarian hyperstimulation syndrome and one possible major complication is venous or arterial thrombosis. Thromboses are rare but potentially serious with important sequellae. They are mostly observed in unusual sites such as head and neck vessels and the mechanism is still unknown although hypotheses have been proposed. This review is an update of our knowledge and an attempt to consider guidelines for the prevention and treatment of ART-associated thromboses, which frequently occur when the woman is pregnant. Prevention of severe ovarian hyperstimulation by appropriate stimulation procedures, detection of women at risk of hyperstimulation and of women at high risk of thrombosis should allow reduction of the risk of thrombosis, possibly by administration of a thromboprophylaxis at a timing and dose which can be only determined by extrapolation.

Antiplatelet agents for preventing pre-eclampsia and its complications

BACKGROUND

Pre-eclampsia is associated with deficient intravascular production of prostacyclin, a vasodilator, and excessive production of thromboxane, a vasoconstrictor and stimulant of platelet aggregation. These observations led to the hypotheses that antiplatelet agents, low-dose aspirin in particular, might prevent or delay development of pre-eclampsia.

OBJECTIVES

To assess the effectiveness and safety of antiplatelet agents for women at risk of developing pre-eclampsia.

SEARCH STRATEGY

We searched the Cochrane Pregnancy and Childbirth Group's Trials Register (July 2006), the Cochrane Central Register of Controlled Trials (The Cochrane Library 2005, Issue 1), EMBASE (1994 to November 2005) and handsearched congress proceedings of the International and European Societies for the Study of Hypertension in Pregnancy.

SELECTION CRITERIA

All randomised trials comparing antiplatelet agents with either placebo or no antiplatelet agent were included. Quasi-random studies were excluded. Participants were pregnant women at risk of developing pre-eclampsia. Interventions were any comparisons of an antiplatelet agent (such as low-dose aspirin or dipyridamole) with either placebo or no antiplatelet.

DATA COLLECTION AND ANALYSIS

Two authors assessed trials for inclusion and extracted data independently.

MAIN RESULTS

Fifty-nine trials (37,560 women) are included. There is a 17% reduction in the risk of pre-eclampsia associated with the use of antiplatelet agents ((46 trials, 32,891 women, relative risk (RR) 0.83, 95% confidence interval (CI) 0.77 to 0.89), number needed to treat (NNT) 72 (52, 119)). Although there is no statistical difference in RR based on maternal risk, there is a significant increase in the absolute risk reduction of pre-eclampsia for high risk (risk difference (RD) -5.2% (-7.5, -2.9), NNT 19 (13, 34)) compared with moderate risk women (RD -0.84 (-1.37, -0.3), NNT 119 (73, 333)). Antiplatelets were associated with an 8% reduction in the relative risk of preterm birth (29 trials, 31,151 women, RR 0.92, 95% CI 0.88 to 0.97); NNT 72 (52, 119)), a 14% reduction in fetal or neonatal deaths (40 trials, 33,098 women, RR 0.86, 95% CI 0.76 to 0.98); NNT 243 (131, 1,666) and a 10% reduction in small-for-gestational age babies (36 trials, 23,638 women, RR 0.90, 95% CI0.83 to 0.98). There were no statistically significant differences between treatment and control groups for any other outcomes.

AUTHORS' CONCLUSIONS

Antiplatelet agents, largely low-dose aspirin, have moderate benefits when used for prevention of pre-eclampsia and its consequences. Further information is required to assess which women are most likely to benefit, when treatment is best started, and at what dose.