The definition of unexplained infertility: A systematic review.

BACKGROUND: There is no consensus on tests required to either diagnose unexplained infertility or use for research inclusion criteria. This leads to heterogeneity and bias affecting meta-analysis and best practice advice. OBJECTIVES: This systematic review analyses the variability of inclusion criteria applied to couples with unexplained infertility. We propose standardised criteria for use both in future research studies and clinical diagnosis. SEARCH STRATEGY: CINAHL and MEDLINE online databases were searched up to November 2022 for all published studies recruiting couples with unexplained infertility, available in full text in the English language. DATA COLLECTION AND ANALYSIS: Data were collected in an Excel spreadsheet. Results were analysed per category and methodology or reference range. MAIN RESULTS: Of 375 relevant studies, only 258 defined their inclusion criteria. The most commonly applied inclusion criteria were semen analysis, tubal patency and assessment of ovulation in 220 (85%), 232 (90%), 205 (79.5%) respectively. Only 87/220 (39.5%) studies reporting semen analysis used the World Health Organization (WHO) limits. Tubal patency was accepted if bilateral in 145/232 (62.5%) and if unilateral in 24/232 (10.3%). Ovulation was assessed using mid-luteal serum progesterone in 115/205 (56.1%) and by a history of regular cycles in 87/205 (42.4%). Other criteria, including uterine cavity assessment and hormone profile, were applied in less than 50% of included studies. CONCLUSIONS: This review highlights the heterogeneity among studied populations with unexplained infertility. Development and application of internationally accepted criteria will improve the quality of research and future clinical care.

Implantation in the lower half of the uterine cavity and decreased trophoblastic thickness can predict subsequent miscarriage: a prospective cohort study.

Abstract: Embryo implantation is vital for successful conception but remains to be fully understood. Trophoblast invasion is key for implantation, with anchorage and depth of placentation determined by its extent. There is a dearth of synchronous information regarding IVF, implantation site, and trophoblastic thickness (TT). Our aim was to determine whether pregnancy implantation site and TT, had an impact on outcomes of IVF pregnancies. This prospective observational study was undertaken at a tertiary referral UK fertility unit over 14 months, collecting data on implantation site and TT from three-dimensional (3D) images of the uterus following early pregnancy scan. Of the 300 women recruited, 277 (92%) had live births, 20 (7%) miscarried, 2 (0.7%) had stillbirths, and 1 (0.3%) had a termination. Significantly more pregnancies that resulted in miscarriage (7/20, 35%) were located in the lower uterine cavity when compared to ongoing pregnancies (15/277, 5%) (P < 0.01). TT was significantly higher in ongoing pregnancies when compared with those who miscarried (7.2 mm vs 5.5 mm; P < 0.01). Implantation in the lower half of the uterine cavity and decreased TT are significantly associated with an increased rate of miscarriage. Identification of those at risk should prompt increased monitoring with the aim of supporting these pregnancies. Lay summary: Implantation of an embryo in the womb is vital for a successful pregnancy. We wanted to find out whether findings on an ultrasound scan in early pregnancy had an impact on outcomes of IVF pregnancies. Three hundred women were recruited to the study, 277 (92%) had live births and unfortunately 20 (7%) had a miscarriage, 2 (0.7%) had stillbirths, and 1 (0.3%) had a termination. Many more of the pregnancies that miscarried implanted in the lower part of the womb. The thickness of the infiltration of the pregnancy into the womb was significantly higher in the ongoing pregnancies. We concluded that implantation in the lower half of the womb and reduced infiltration of the pregnancy seen on scan are associated with an increased rate of miscarriage. We propose that when we identify those at risk, we should increase monitoring, with the aim of supporting these pregnancies.

Should women with high body mass index be denied fertility treatments?

Obesity is an emerging global epidemic with a negative impact on fertility. Almost all guidelines and policies have a stringent limit of body mass index (BMI) to access fertility services which has promoted a debate amongst fertility practitioners globally. Proponents of placing such a limit point to the negative impact of elevated BMI on the outcome of fertility treatment, its cost effectiveness and the risk it poses to the intending mother and unborn child. Opponents of placing a restriction base their arguments on the lack of conclusive, robust evidence regarding the variables along with the ethical dilemmas of promoting discrimination and stigmatization by denying a couple their basic right of parenthood. In this review, we analyse these medical and ethical dilemmas in the light of current evidence. The focus is on female infertility.

Correlation of IVF outcomes and number of oocytes retrieved: a UK retrospective longitudinal observational study of 172 341 non-donor cycles.

OBJECTIVE: How do numbers of oocytes retrieved per In vitro fertilisation (IVF) cycle impact on the live birth rate (LBR) and multiple gestation pregnancy (MGP) rates? DESIGN: Retrospective observational longitudinal study. SETTING: UK IVF clinics. POPULATION: Non-donor IVF patients. MAIN OUTCOME MEASURES: LBR per IVF cycle and MGP levels against number of oocytes retrieved into subgroups: 0, 1-5, 6-15, 16-25, 26-49 oocytes and 50+ oocytes. Relative risk (RR) and 95% CIs were calculated for each group against the intermediate responder with '6-15 oocytes collected'. RESULTS: From 172 341 attempted fresh oocyte retrieval cycles, the oocyte retrieved was: 0 in 10 148 (5.9%) cycles from 9439 patients; 1-5 oocytes in 42 574 cycles (24.7%); 6-15 oocytes in 91 797 cycles (53.3%); 16-25 oocytes in 23 794 cycles (13.8%); 26-49 oocytes in 3970 cycles (2.3%); ≥50 oocytes in 58 cycles (0.033%). The LBRs for the 1-5, 6-15, 16-25 and 26-49 subgroups of oocytes retrieved were 17.2%, 32.4%, 35.3% and 18.7%, respectively. The RR (95% CI) of live birth in comparison to the intermediate group (6-15) for 1-5, 16-25 and 26-49 groups was 0.53 (0.52 to 0.54), 1.09 (1.07 to 1.11) and 0.58 (0.54 to 0.62), respectively. The corresponding MGP rates and RR were 9.2%, 11.0%, 11.4% and 11.3%, respectively and 0.83 (0.77 to 0.90), 1.04 (0.97 to 1.11) and 1.03 (0.84 to 1.26), respectively. CONCLUSION: There was only limited benefit in LBR beyond the 6-15 oocyte group going to the 16-25 oocytes group, after which there was significant decline in LBR. The MGP risk was lower in 1-5 group.

Endogenous progesterone in unexplained infertility: a systematic review and meta-analysis.

PURPOSE: To investigate the possibility that altered actions of endogenous progesterone affect receptivity and contribute to unexplained infertility (UI). METHODS: Two authors electronically searched MEDLINE, CINAHL and Embase databases from inception to 6 July 2022 and hand-searched according to Cochrane methodology. We included all published primary research reporting outcomes related to endogenous progesterone in natural cycles in women with UI. Studies were assessed for risk of bias using a modified Newcastle-Ottawa Score or NHLBI Score. We pooled results where appropriate using a random-effects model. Findings were reported as odds ratios or mean differences. RESULTS: We included 41 studies (n = 4023). No difference was found between the mid-luteal serum progesterone levels of women with UI compared to fertile controls (MD 0.74, - 0.31-1.79, I2 36%). Women with UI had significantly higher rates of 'out-of-phase' endometrium than controls. Nine out of 10 progesterone-mediated markers of endometrial receptivity were significantly reduced in women with UI compared to fertile controls (the remaining 1 had conflicting results). Resistance in pelvic vessels was increased and perfusion of the endometrium and sub-endometrium reduced in UI compared to fertile controls in all included studies. Progesterone receptor expression and progesterone uptake were also reduced in women with unexplained infertility. CONCLUSIONS: End-organ measures of endogenous progesterone activity are reduced in women with UI compared to fertile controls. This apparently receptor-mediated reduction in response affects endometrial receptivity and is implicated as the cause of the infertility. Further research is required to confirm whether intervention could overcome this issue, offering a new option for treating unexplained infertility. TRIAL REGISTRATION: PROSPERO registration: CRD42020141041 06/08/2020.

Effect of cigarette smoking on serum anti-Mullerian hormone and antral follicle count in women seeking fertility treatment: a prospective cross-sectional study.

OBJECTIVES: The relationship between smoking and ovarian reserve markers is inconclusive. The primary objective of our study was to assess the effect of cigarette smoking on the quantitative ovarian reserve parameters, serum anti-Mullerian hormone (AMH) and antral follicle count (AFC) as relevant to prediction of fertility outcomes in women seeking fertility treatment. Our secondary aims were to validate self-reported smoking behaviour using biomarkers and evaluate the association between biomarkers of ovarian reserve (serum AMH and AFC) with biomarkers of smoking exposure (breath carbon monoxide (CO) and urine cotinine levels). DESIGN: Prospective, cross-sectional study. SETTING: Single tertiary care fertility centre. PARTICIPANTS: Women ≤35 years seeking fertility treatment. PRIMARY OUTCOME MEASURES: Serum AMH and AFC. RESULTS: Significant differences were found among current smokers, ex-smokers and never smokers for breath CO (F(2,97)=33.32, p<0.0001) and urine cotinine levels (p<0.001). However, no significant differences were found either for serum AMH (F(2,91)=1.19, p=0.309) or total AFC (F(2,81)=0.403, p=0.670) among the three groups. There was no significant correlation between pack years of smoking and serum AMH (r=-0.212, n=23, p=0.166) or total AFC (r=-0.276, n=19, p=0.126). No significant correlation was demonstrated between breath CO and serum AMH (r=0.082, n=94, p=0.216) or total AFC (r=0.096, n=83, p=0.195). Similarly, no significant correlation was demonstrated between urine cotinine levels and serum AMH (r=0.146, n=83, p=0.095) or total AFC (r=-0.027, n=77, p=0.386). CONCLUSION: We did not find a statistically significant difference in quantitative ovarian reserve markers between current smokers, ex-smokers and never smokers which would be clinically meaningful in our study population. We confirmed that self-reported smoking correlates well with quantitatively measured biomarkers of smoking. This validated the self-reported comparison groups to ensure a valid comparison of outcome measures. There was no significant association between biomarkers of smoking and biomarkers of ovarian reserve. We were also unable to demonstrate a correlation between the lifetime smoking exposure and ovarian reserve.

IUI is a better alternative than IVF as the first-line treatment of unexplained infertility.

The treatment of a condition with no known cause, such as unexplained infertility is, unsurprisingly, controversial. The alternatives that have been suggested for the first-line treatment are expectant management, ovarian stimulation, intrauterine insemination (IUI) with or without ovarian stimulation, or IVF. As far as live births are concerned, the choice has realistically been narrowed down to IUI with ovarian stimulation by low-dose gonadotrophins using strict cancellation criteria versus IVF. In several well-designed studies, three cycles of the former have proved as successful as one cycle of IVF. As IUI is less invasive, more comfortable for the patient, markedly less expensive and safe with a high compliance rate, it should be recommended for the first-line treatment of unexplained infertility for couples in whom the woman's age is not more than 38 years.

Global inequality in sub-fertility treatment needs safer, cost effective, evidence-based and economically viable choices for patients and stakeholders.

The global increase in subfertility diagnosis and treatments and the rise of private equity investors concentrating on high profits based on in vitro fertilisation (IVF) treatments raise profound societal and economic questions for stakeholders and patients. The question remains as to whose benefits will ultimately be greater when promoting high margins treatment options resulting from cross-border mergers and acquisitions of IVF clinics.This paper covers wide-ranging issues from the erroneously constructed UK National Institute for Health and Care Excellence's (NICE) guidelines on treatment choices, the cost-effectiveness of treatments, the promotion of IVF, and add-ons where evidence remains minimal, the commercial size of the fertility industry. Investment in improving intrauterine insemination (IUI) success rates has understandably been avoided for its short-term impact on the IVF industry. However, IUI efficiency would cut across many of the global subfertility treatment economic and access problems while allowing stakeholder, feepaying, and patients financial savings will likely allow for more funded IVF cycles in acutely deserving cases. The recommendations will help expand choices for globally economically challenged patients' and services while enhancing an ethical and moral dimension towards fertility treatment choices for patients and stakeholders.

National Survey Highlights the Urgent Need for Standardisation of Embryo Transfer Techniques in the UK.

Embryo transfer (ET) is one of the vital steps in the in vitro fertilisation (IVF) process, yet there is wide variation in ET technique throughout the UK, without a nationally approved standardised approach. The aim of this study was to gain contemporaneous information regarding the current clinical ET practice in the UK. METHOD: A 38-question electronic survey was distributed to the 79 UK Human Fertilisation and Embryology Authority (HFEA) registered clinics performing ETs. RESULTS: In total, 59% (47/79) of units responded, 83% (39/47) performing ultrasound-guided transfers, with 42% (20/47) of units using a tenaculum; 22% (10/45) would proceed with transfer regardless of fluid in the endometrial cavity. In 91% (43/47) of units, embryos were deposited in the upper/middle portion of the uterine cavity, but interpretation of this area ranged from 0.5 to >2 cm from the fundus, with 68% (32/47) allowing patients to mobilise immediately after transfer. In 60% (27/45) of clinics, success rates were based on clinical pregnancy rates (CPR). CONCLUSION: Within the UK there is a wide range of variability in ET techniques, with >70% of discordance in survey-responses between clinics. Whilst there are areas of good practice, some disadvantageous techniques continue to persist. This survey emphasises the importance of developing a standardised, evidence-based approach to improve ET success rates.

When Should We Freeze Embryos? Current Data for Fresh and Frozen Embryo Replacement IVF Cycles.

Recent years have seen a dramatic rise in the number of frozen-thawed embryo replacement (FER) cycles. Along with the advances in embryo cryopreservation techniques, the optimization of endometrial receptivity has resulted in outcomes for FER that are similar to fresh embryo transfer. However, the question of whether the Freeze all strategy is for all is nowadays a hot topic. This review addresses this issue and describes current evidence based on randomized controlled trials and observational studies. To date, it is reasonable to perform FER in cases with a clear indication for the benefits of such strategy including impending ovarian hyperstimulation syndrome (OHSS) or preimplantation genetic testing for aneuploidy (PGT-A); however, this strategy does not fit for all. This review analyses the pros and cons of the freeze all strategy highlighting the need to follow a personalized plan in embryo transfer, avoiding a freeze all methodology for all patients in an unselected manner.

Effects of metformin treatment on pregnancy outcomes in patients with polycystic ovary syndrome.

INTRODUCTION: This review covers the current evidence regarding the use of metformin as a therapeutic intervention for optimizing pregnancy outcomes in women with polycystic ovary syndrome (PCOS). AREAS COVERED: After searching Medline, Embase and CINAHL, all important large clinical trials and observational studies plus systematic reviews, meta-analyses and Cochrane reviews have been summarized here. The results have been compared to culminate in a thorough review and discussion on the use of metformin in relation to reproductive outcomes for women with PCOS. The role of metformin in PCOS is explored both in terms of achieving conception and during pregnancy. The existing evidence around metformin use is summarized both during the preconceptual period and during pregnancy, in relation to reproductive outcomes. EXPERT OPINION: Metformin is a widely used medication, often prescribed to improve reproductive outcomes for women with PCOS. However, the evidence remains equivocal regarding its efficacy both in optimizing fertility and pregnancy outcomes. More research is required with special emphasis on metformin use within different populations, including ethnic groups and women with varying BMI ranges.

IUI needs fairer appraisal to improve patient and stakeholder choices.

Information supporting IVF at the expense of intrauterine insemination (IUI) has become commonplace, but it lacks critical analyses. Data from poorly practiced IUI, without an equivalent comparison to IVF, has been generalised to recommend a total abandonment of IUI in favour of IVF treatment. Our intention with this paper is to reappraise and balance arguments so that patients and stakeholders can have an unbiased informed choice. We provide information that reveals IUI to predominate over IVF in terms of integrated success, risks and cost to deliver one live birth whilst obviating the maternal and neonatal costs. Exceptional cost savings are demonstrated for IUI over IVF for fee-paying agencies and patients with lowered risks of maternal and neonatal care along with other risks including OHSS, fetal reduction and termination of pregnancies. This analysis supports the view that patients and stakeholders can choose IUI instead of IVF in most instances, except with bilateral tubal blockage and severe male factor infertility. It is apparent that fertility clinics need to re-evaluate and reconsider this field, and IUI can be of benefit to both subfertile patients and the stakeholders.

Outcome of mock embryo transfer before the first IVF cycle: A randomized control trial.

BACKGROUND: There is a lack of agreement among fertility specialists with regard to the routine use of mock embryo transfer (MET) before each in vitro fertilization (IVF) treatment cycle. While MET may be beneficial with previous difficult embryo transfer cases, its routine use before first IVF cycle has not been evaluated. OBJECTIVE: To find out the effect of MET before the first IVF cycle on clinical pregnancy rate. MATERIALS AND METHODS: This is a single-centre randomized controlled trial with a balanced randomization (1:1), carried out between November 2015 and October 2017, with 200 subjects at Homerton university hospital, London, randomized into either MET or control. The primary outcome was clinical pregnancy rate (detection of heart activity on the ultrasound scan), the secondary outcome measures were live birth rate, miscarriage and multiple pregnancy rates, difficult ETs, rate of blood or mucus on the catheter tip. RESULTS: No significant differences were observed in the baseline or cycle characteristics between the two groups. The clinical pregnancy rate was similar between the MET and control groups based on both intension to treat and per protocol analyses (p = 0.98, p = 0.92, respectively). Additionally, no significant difference was seen in the live birth rate in both groups on intension to treat and per protocol analyses (p = 0.67, p = 0.47), respectively. CONCLUSION: Our study concludes that MET prior to first IVF cycle may not improve the success rate in young women without risk factors for a difficult embryo transfer.

SARS-CoV-2: diagnostic and design conundrums in the context of male factor infertility.

The question of whether SARS-CoV-2 (severe acute respiratory syndrome-related coronavirus-2 [SARS-CoV-2], leading to the COVID-19 infection) can be harboured in the testes and/or semen is currently unanswered. It is essential to understand the limitations of both antibody and real-time PCR tests in interpreting SARS-CoV-2 data in relation to analyses of semen and testicular tissue without appropriate controls. This article critically analyses the evidence so far on this, and the possible implications. The limitations of diagnostic tests in both sampling and testing methodologies, their validation and their relevance in interpreting data are also highlighted.

Observational retrospective study of UK national success, risks and costs for 319,105 IVF/ICSI and 30,669 IUI treatment cycles.

OBJECTIVE: To compare success rates, associated risks and cost-effectiveness between intrauterine insemination (IUI) and in vitro fertilisation (IVF). DESIGN: Retrospective observational study. SETTING: The UK from 2012 to 2016. PARTICIPANTS: Data from Human Fertilisation and Embryology Authority's freedom of information request for 2012-2016 for IVF/ICSI (intracytoplasmic sperm injection)and IUI as practiced in 319 105 IVF/ICSI and 30 669 IUI cycles. Direct-cost calculations for maternal and neonatal expenditure per live birth (LB) was constructed using the cost of multiple birth model, with inflation-adjusted Bank of England index-linked data. A second direct-cost analysis evaluating the incremental cost-effective ratio (ICER) was modelled using the 2016 national mean (baseline) IVF and IUI success rates. OUTCOME MEASURES: LB, risks from IVF and IUI, and costs to gain 1 LB. RESULTS: This largest comprehensive analysis integrating success, risks and costs at a national level shows IUI is safer and more cost-effective than IVF treatment.IVF LB/cycle success was significantly better than IUI at 26.96% versus 11.49% (p<0.001) but the IUI success is much closer to IVF at 2.35:1, than previously considered. IVF remains a significant source of multiple gestation pregnancy (MGP) compared with IUI (RR (Relative Risk): 1.45 (1.31 to 1.60), p<0.001) as was the rate of twins (RR: 1.58, p<0.001).In 2016, IVF maternal and neonatal cost was £115 082 017 compared with £2 940 196 for IUI and this MGP-related perinatal cost is absorbed by the National Health Services. At baseline tariffs and success rates IUI was £42 558 cheaper than IVF to deliver 1LB with enhanced benefits with small improvements in IUI. Reliable levels of IVF-related MGP, OHSS (ovarian hyperstimulation syndrome), fetal reductions and terminations are revealed. CONCLUSION: IUI success rates are much closer to IVF than previously reported, more cost-effective in delivering 1 LB, and associated with lower risk of complications for maternal and neonatal complications. It is prudent to offer IUI before IVF nationally.

The regulation and signalling of anti-Müllerian hormone in human granulosa cells: relevance to polycystic ovary syndrome.

STUDY QUESTION: What prevents the fall in anti-Müllerian hormone (AMH) levels in polycystic ovary syndrome (PCOS) and what are the consequences of this for follicle progression in these ovaries? SUMMARY ANSWER: Exposure of granulosa cells (GCs) to high levels of androgens, equivalent to that found in PCOS, prevented the fall in AMH and was associated with dysregulated AMH-SMAD signalling leading to stalled follicle progression in PCOS. WHAT IS KNOWN ALREADY: In normal ovaries, AMH exerts an inhibitory role on antral follicle development and a fall in AMH levels is a prerequisite for ovulation. Levels of AMH are high in PCOS, contributing to the dysregulated follicle growth that is a common cause of anovulatory infertility in these women. STUDY DESIGN, SIZE, DURATION: Human KGN-GC (the cell line that corresponds to immature GC from smaller antral follicles (AF)) were cultured with a range of doses of various androgens to determine the effects on AMH production. KGN-GC were also treated with PHTPP (an oestrogen receptor ß (ERß) antagonist) to examine the relationship between AMH expression and the ratio of ERα:ERß. The differential dose-related effect of AMH on gene expression and SMAD signalling was investigated in human granulosa-luteal cells (hGLC) from women with normal ovaries, with polycystic ovarian morphology (PCOM) and with PCOS. KGN-GC were also cultured for a prolonged period with AMH at different doses to assess the effect on cell proliferation and viability. PARTICIPANTS/MATERIALS, SETTING, METHODS: AMH protein production by cells exposed to androgens was measured by ELISA. The effect of PHTPP on the mRNA expression levels of AMH, ERα and ERß was assessed by real-time quantitative PCR (qPCR). The influence of AMH on the relative mRNA expression levels of aromatase, AMH and its receptor AMHRII, and the FSH and LH receptor (FSHR and LHR) in control, PCOM and PCOS hGLCs was quantified by qPCR. Western blotting was used to assess changes in levels of SMAD proteins (pSMAD-1/5/8; SMAD-4; SMAD-6 and SMAD-7) after exposure of hGLCs from healthy women and women with PCOS to AMH. The ApoTox-Glo Triplex assay was used to evaluate the effect of AMH on cell viability, cytotoxicity and apoptosis. MAIN RESULTS AND THE ROLE OF CHANCE: Testosterone reduced AMH protein secreted from KGN-GC at 10-9-10-7 M (P < 0.05; P < 0.005, multiple uncorrected comparisons Fishers least squares difference), but at equivalent hyperandrogenemic levels no change was seen in AMH levels. 5α-DHT produced a significant dose-related increase in AMH protein secreted into the media (P = 0.022, ANOVA). Increasing the mRNA ratio of ERα:ERß produced a corresponding increase in AMH mRNA expression (P = 0.015, two-way ANOVA). AMH increased mRNA levels of aromatase (P < 0.05, one-way ANOVA) and FSHR (P < 0.0001, one-way ANOVA) in hGLCs from women with PCOM, but not from normal cells or PCOS (normal n = 7, PCOM n = 5, PCOS n = 4). In contrast to hGLCs from ovulatory ovaries, in PCOS AMH reduced protein levels (cell content) of stimulatory pSMAD-1/5/8 and SMAD-4 but increased inhibitory SMAD-6 and -7 (P < 0.05, normal n = 6, PCOS n = 3). AMH at 20 and 50 ng/ml decreased KGN-GC cell proliferation but not viability after 8 days of treatment (P < 0.005, two-way ANOVA). LARGE SCALE DATA: N/A. LIMITATIONS, REASONS FOR CAUTION: Luteinised GC from women undergoing IVF have a relatively low expression of AMH/AMHRII but advantageously continue to display responses inherent to the ovarian morphology from which they are collected. To compensate, we also utilised the KGN cell line which has been characterised to be at a developmental stage close to that of immature GC. The lack of flutamide influence on testosterone effects is not in itself sufficient evidence to conclude that the effect on AMH is mediated via conversion to oestrogen, and the effect of aromatase inhibitors or oestrogen-specific inhibitors should be tested. The effect of flutamide was tested on testosterone but not DHT. WIDER IMPLICATIONS OF THE FINDINGS: Normal folliculogenesis and ovulation are dependent on the timely reduction in AMH production from GC at the time of follicle selection. Our findings reveal for the first time that theca-derived androgens may play a role in this model but that this inhibitory action is lost at levels of androgens equivalent to those seen in PCOS. The AMH decline may either be a direct effect of androgens or an indirect one via conversion to oestradiol and acting through the upregulation of ERα, which is known to stimulate the AMH promoter. Interestingly, the ability of GCs to respond to this continually elevated AMH level appears to be reduced in cells from women with PCOS due to an adaptive alteration in the SMAD signalling pathway and lower expression of AMHRII, indicating a form of 'AMH resistance'. STUDY FUNDING/COMPETING INTEREST(S): This study was funded by the Thomas Addison Scholarship, St Georges Hospital Trust. The authors report no conflict of interest in this work and have nothing to disclose. TRIAL REGISTRATION NUMBER: N/A.

First-line ovulation induction for polycystic ovary syndrome: an individual participant data meta-analysis.

BACKGROUND: Polycystic ovary syndrome (PCOS) is the most frequent cause of anovulatory infertility. In women with PCOS, effective ovulation induction serves as an important first-line treatment for anovulatory infertility. Individual participant data (IPD) meta-analysis is considered as the gold standard for evidence synthesis which provides accurate assessments of outcomes from primary randomised controlled trials (RCTs) and allows additional analyses for time-to-event outcomes. It also facilitates treatment-covariate interaction analyses and therefore offers an opportunity for personalised medicine. OBJECTIVE AND RATIONALE: We aimed to evaluate the effectiveness of different ovulation induction agents, in particular letrozole alone and clomiphene citrate (CC) plus metformin, as compared to CC alone, as the first-line choice for ovulation induction in women with PCOS and infertility, and to explore interactions between treatment and participant-level baseline characteristics. SEARCH METHODS: We searched electronic databases including MEDLINE, EMBASE and Cochrane Central Register of Controlled Trials up to 20 December 2018. We included RCTs comparing the following interventions with each other or placebo/no treatment in women with PCOS and infertility: CC, metformin, CC plus metformin, letrozole, gonadotrophin and tamoxifen. We excluded studies on treatment-resistant women. The primary outcome was live birth. We contacted the investigators of eligible RCTs to share the IPD and performed IPD meta-analyses. We assessed the risk of bias by using the Cochrane risk of bias tool for RCTs. OUTCOMES: IPD of 20 RCTs including 3962 women with PCOS were obtained. Six RCTs compared letrozole and CC in 1284 women. Compared with CC, letrozole improved live birth rates (3 RCTs, 1043 women, risk ratio [RR] 1.43, 95% confidence interval [CI] 1.17-1.75, moderate-certainty evidence) and clinical pregnancy rates (6 RCTs, 1284 women, RR 1.45, 95% CI 1.23-1.70, moderate-certainty evidence) and reduced time-to-pregnancy (6 RCTs, 1235 women, hazard ratio [HR] 1.72, 95% CI 1.38-2.15, moderate-certainty evidence). Meta-analyses of effect modifications showed a positive interaction between baseline serum total testosterone levels and treatment effects on live birth (interaction RR 1.29, 95% CI 1.01-1.65). Eight RCTs compared CC plus metformin to CC alone in 1039 women. Compared with CC alone, CC plus metformin might improve clinical pregnancy rates (8 RCTs, 1039 women, RR 1.18, 95% CI 1.00-1.39, low-certainty evidence) and might reduce time-to-pregnancy (7 RCTs, 898 women, HR 1.25, 95% CI 1.00-1.57, low-certainty evidence), but there was insufficient evidence of a difference on live birth rates (5 RCTs, 907 women, RR 1.08, 95% CI 0.87-1.35, low-certainty evidence). Meta-analyses of effect modifications showed a positive interaction between baseline insulin levels and treatment effects on live birth in the comparison between CC plus metformin and CC (interaction RR 1.03, 95% CI 1.01-1.06). WIDER IMPLICATIONS: In women with PCOS, letrozole improves live birth and clinical pregnancy rates and reduces time-to-pregnancy compared to CC and therefore can be recommended as the preferred first-line treatment for women with PCOS and infertility. CC plus metformin may increase clinical pregnancy and may reduce time-to-pregnancy compared to CC alone, while there is insufficient evidence of a difference on live birth. Treatment effects of letrozole are influenced by baseline serum levels of total testosterone, while those of CC plus metformin are affected by baseline serum levels of insulin. These interactions between treatments and biomarkers on hyperandrogenaemia and insulin resistance provide further insights into a personalised approach for the management of anovulatory infertility related to PCOS.