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Background: There is a substantial body of research evaluating ways to prevent and manage miscarriage, but all studies do not report on the same outcomes.Objective: To review systematically, outcomes reported in existing miscarriage trials.Search Strategy: MEDLINE, Embase, CINAHL, and Cochrane were searched from inception until January 2017.Selection Criteria: Randomised controlled trials (RCTs) reporting prevention or management of miscarriage. Miscarriage was defined as a pregnancy loss in the first trimester.Data Collection and Analysis: Data about the study characteristics, primary, and secondary outcomes were extracted.Main Results: We retrieved 1553 titles and abstracts, from which 208 RCTs were included. For prevention of miscarriage, the most commonly reported primary outcome was live birth and the top four reported outcomes were pregnancy loss/stillbirth (n = 112), gestation of birth (n = 68), birth dimensions (n = 65), and live birth (n = 49). For these four outcomes, 58 specific measures were used for evaluation. For management of miscarriage, the most commonly reported primary outcome was efficacy of treatment. The top four reported outcomes were bleeding (n = 186), efficacy of miscarriage treatment (n = 105), infection (n = 97), and quality of life (n = 90). For these outcomes, 130 specific measures were used for evaluation.Conclusions: Our review found considerable variation in the reporting of primary and secondary outcomes along with the measures used to assess them. There is a need for standardised patient-centred clinical outcomes through the development of a core outcome set; the work from this systematic review will form the foundation of the core outcome set for miscarriage.Tweetable Abstract: There is disparity in the reporting of outcomes and the measures used to assess them in miscarriage trials. [ABSTRACT FROM AUTHOR]

Objective: To examine the association between periconceptual maternal diet and miscarriage risk among women with recurrent miscarriages., Design: Prospective multicentre cohort study (Tommy's Net)., Setting: Three university hospital research centres in the United Kingdom., Population: 1035 women with a baseline history of two or more miscarriages., Methods: We analysed baseline dietary data from a 10-item Food Frequency Questionnaire (FFQ). For individual food category analyses, we used multivariable Poisson regression following adjustment for maternal confounders and paternal dietary patterns. For whole diet analyses, ordinal principal component analysis (PCA) was used to identify common dietary patterns. Results were presented as relative risks (RR) with 95% confidence intervals (CI) and accompanying p-values., Main Outcome Measures: Miscarriage rate, defined as the rate of spontaneous pregnancy loss (< 24 weeks of gestation) relative to the total number of pregnancies (miscarriages and live births)., Results: High consumption of fruit and nuts (almonds and walnuts) was associated with lower miscarriage risk (fruit 226/662 (34.1%) vs. 38/77 (49.4%), RR 0.66, 95% CI 0.51 to 0.85, p = 0.001; nuts 47/152 (30.9%) vs. 220/613 (35.9%), RR 0.73, 95% CI 0.54 to 0.98, p = 0.039). High red meat intake was associated with a possible increase in miscarriage risk (6/12 (50.0%) vs. 165/469 (35.2%), RR 1.86, 95% CI 1.10 to 3.16, p = 0.022). The association with miscarriage risk was unclear for other food groups, including fresh vegetables, white meat, fish, dairy, eggs, soya and chocolate, due to imprecise point estimates. Through PCA, we identified three data-derived dietary patterns. Yet, no distinct relationship emerged between these dietary patterns and miscarriage risk., Conclusions: A maternal diet rich in fresh fruits and nuts is associated with a lower miscarriage risk among women with a history of recurrent miscarriage., Trail Registration: Tommy's Net (ISRCTN17732518) https://www.isrctn.com/ISRCTN17732518. Analysis plan (OSF zp7cs) https://osf.io/zp7cs., (© 2024 The Author(s). BJOG: An International Journal of Obstetrics and Gynaecology published by John Wiley & Sons Ltd.)

Background: International guidelines recommend targeted screening to identify gestational thyroid dysfunction. However, currently used risk factors have questionable discriminative ability. We quantified the risk for thyroid function test abnormalities for a subset of risk factors currently used in international guidelines. Methods: We included prospective cohort studies with data on gestational maternal thyroid function and potential risk factors (maternal age, body mass index [BMI], parity, smoking status, pregnancy through in vitro fertilization, twin pregnancy, gestational age, maternal education, and thyroid peroxidase antibody [TPOAb] or thyroglobulin antibody [TgAb] positivity). Exclusion criteria were pre-existing thyroid disease and use of thyroid interfering medication. We analyzed individual participant data using mixed-effects regression models. Primary outcomes were overt and subclinical hypothyroidism and a treatment indication (defined as overt hypothyroidism, subclinical hypothyroidism with thyrotropin >10 mU/L, or subclinical hypothyroidism with TPOAb positivity). Results: The study population comprised 65,559 participants in 25 cohorts. The screening rate in cohorts using risk factors currently recommended (age >30 years, parity ≥2, BMI ≥40) was 58%, with a detection rate for overt and subclinical hypothyroidism of 59%. The absolute risk for overt or subclinical hypothyroidism varied <2% over the full range of age and BMI and for any parity. Receiver operating characteristic curves, fitted using maternal age, BMI, smoking status, parity, and gestational age at blood sampling as explanatory variables, yielded areas under the curve ranging from 0.58 to 0.63 for the primary outcomes. TPOAbs/TgAbs positivity was associated with overt hypothyroidism (approximate risk for antibody negativity 0.1%, isolated TgAb positivity 2.4%, isolated TPOAb positivity 3.8%, combined antibody positivity 7.0%; p  < 0.001), subclinical hypothyroidism (risk for antibody negativity 2.2%, isolated TgAb positivity 8.1%, isolated TPOAb positivity 14.2%, combined antibody positivity 20.0%; p  < 0.001) and a treatment indication (risk for antibody negativity 0.2%, isolated TgAb positivity 2.2%, isolated TPOAb positivity 3.0%, and combined antibody positivity 5.1%; p  < 0.001). Twin pregnancy was associated with a higher risk of overt hyperthyroidism (5.6% vs. 0.7%; p  < 0.001). Conclusions: The risk factors assessed in this study had poor predictive ability for detecting thyroid function test abnormalities, questioning their clinical usability for targeted screening. As expected, TPOAb positivity (used as a benchmark) was a relevant risk factor for (subclinical) hypothyroidism. These results provide insights into different risk factors for gestational thyroid dysfunction.

Study Question: Are morphokinetic models better at prioritizing a euploid embryo for transfer over morphological selection by an embryologist?, Summary Answer: Morphokinetic algorithms lead to an improved prioritization of euploid embryos when compared to embryologist selection., What Is Known Already: PREFER (predicting euploidy for embryos in reproductive medicine) is a previously published morphokinetic model associated with live birth and miscarriage. The second model uses live birth as the target outcome (LB model)., Study Design, Size, Duration: Data for this cohort study were obtained from 1958 biopsied blastocysts at nine IVF clinics across the UK from January 2021 to December 2022., Participants/materials, Setting, Methods: The ability of the PREFER and LB models to prioritize a euploid embryo was compared against arbitrary selection and the prediction of four embryologists using the timelapse video, blinded to the morphokinetic time stamp. The comparisons were made using calculated percentages and normalized discounted cumulative gain (NDCG), whereby an NDCG score of 1 would equate to all euploid embryos being ranked first. In arbitrary selection, the ploidy status was randomly assigned within each cycle and the NDGC calculated, and this was then repeated 100 times and the mean obtained., Main Results and the Role of Chance: Arbitrary embryo selection would rank a euploid embryo first 37% of the time, embryologist selection 39%, and the LB and PREFER ploidy morphokinetic models 46% and 47% of the time, respectively. The AUC for LB and PREFER model was 0.62 and 0.63, respectively. Morphological selection did not significantly improve the performance of both morphokinetic models when used in combination. There was a significant difference between the NDGC metric of the PREFER model versus embryologist selection at 0.96 and 0.87, respectively (t = 14.1, P < 0.001). Similarly, there was a significant difference between the LB model and embryologist selection with an NDGC metric of 0.95 and 0.87, respectively (t = 12.0, P < 0.001). All four embryologists ranked embryos similarly, with an intraclass coefficient of 0.91 (95% CI 0.82-0.95, P < 0.001)., Limitations, Reasons for Caution: Aside from the retrospective study design, limitations include allowing the embryologist to watch the time lapse video, potentially providing more information than a truly static morphological assessment. Furthermore, the embryologists at the participating centres were familiar with the significant variables in time lapse, which could bias the results., Wider Implications of the Findings: The present study shows that the use of morphokinetic models, namely PREFER and LB, translates into improved euploid embryo selection., Study Funding/competing Interest(s): This study received no specific grant funding from any funding agency in the public, commercial or not-for-profit sectors. Dr Alison Campbell is minor share holder of Care Fertility. All other authors have no conflicts of interest to declare. Time lapse is a technology for which patients are charged extra at participating centres., Trial Registration Number: N/A., (© The Author(s) 2023. Published by Oxford University Press on behalf of European Society of Human Reproduction and Embryology. All rights reserved. For permissions, please email: journals.permissions@oup.com.)

Approximately 80% of miscarriages happen within the first 12 weeks of gestation. More than half of early losses result from genetic defects, usually presenting as abnormal chromosome numbers or gene rearrangements in the embryo. However, the impact of genetics on pregnancy loss goes well beyond embryonic aneuploidy. For example, the use of big data has recently led to the discovery of specific gene mutations that may be implicated in sporadic and recurrent miscarriages. Further, emerging data suggest that genetic factors play a role in conditions for which there is a causative association with recurrent pregnancy loss. Here, we summarize the evidence on the genetics of miscarriage and provide an overview of the diagnosis and prevention of genetic causes associated with sporadic and recurrent pregnancy loss., Competing Interests: Declaration of interests P.M. is funded by a UK National Institute for Health and Care Research Academic Clinical Lectureship. R.D.S. has nothing to disclose. M.A.I. has nothing to disclose. A.D. has nothing to disclose. A.C. has nothing to disclose., (Crown Copyright © 2023. Published by Elsevier Inc. All rights reserved.)

Objective: To determine whether the aneuploidy risk score from a morphokinetic ploidy prediction model, Predicting Euploidy for Embryos in Reproductive Medicine (PREFER), is associated with miscarriage and live birth outcomes., Design: Multicentre cohort study., Setting: Nine in vitro fertilization clinics in the United Kingdom., Patients: Data were obtained from the treatment of patients from 2016-2019. A total of 3587 fresh single embryo transfers were included; preimplantation genetic testing for aneuploidy) cycles were excluded., Intervention: PREFER is a model developed using 8,147 biopsied blastocyst specimens to predict ploidy status using morphokinetic and clinical biodata. A second model using only morphokinetic (MK) predictors was developed, P PREFER-MK. The models will categorize embryos into the following three risk score categories for aneuploidy: "high risk," "medium risk," and "low risk.", Main Outcome Measures: The primary outcomes are miscarriage and live birth. Secondary outcomes include biochemical clinical pregnancy per single embryo transfer., Results: When applying PREFER, the miscarriage rates were 12%, 14%, and 22% in the "low risk," "moderate risk," and "high risk" categories, respectively. Those embryos deemed "high risk" had a significantly higher egg provider age compared with "low risk," and there was little variation in risk categories in patients of the same age. The trend in miscarriage rate was not seen when using PREFER-MK; however, there was an association with live birth, increasing from 38%-49% and 50% in the "high risk," "moderate risk," and "low risk" groups, respectively. An adjusted logistic regression analysis demonstrated that PREFER-MK was not associated with miscarriage when comparing "high risk" to "moderate risk" embryos (odds ratio [OR], 0.87; 95% confidence interval [CI], 0.63-1.63) or "high risk" to "low risk" embryos (OR, 1.07; 95% CI, 0.79-1.46). An embryo deemed "low risk" by PREFER-MK was significantly more likely to result in a live birth than those embryos graded "high risk" (OR, 1.95; 95% CI, 1.65-2.25)., Conclusion: The PREFER model's risk scores were significantly associated with live births and miscarriages. Importantly, this study also found that this model applied too much weight to clinical factors, such that it could no longer rank a patient's embryos effectively. Therefore, a model including only MKs would be preferred; this was similarly associated with live birth but not miscarriage., (Copyright © 2023 American Society for Reproductive Medicine. Published by Elsevier Inc. All rights reserved.)

Importance: The evidence on the association between diet and miscarriage risk is scant and conflicting., Objective: To summarize the evidence on the association between periconceptual diet and miscarriage risk in healthy women of reproductive age., Data Sources: Electronic databases were searched from inception to August 2022 without restriction of regions, publication types, or languages., Study Selection and Synthesis: Experimental or observational studies were considered for inclusion. The population was healthy women of reproductive age. Exposure was periconception diet. Study quality was assessed using the modified Newcastle-Ottawa Scale. Summary effect sizes (odds ratio [OR] with 95% confidence interval [CI]) were calculated for each food category., Main Outcomes: Miscarriage rate (as defined by primary studies)., Results: We included 20 studies (11 cohort and 9 case-control), of which 6 presented data suitable for meta-analysis (2 cohort and 4 case-control, n = 13,183 women). Our primary analyses suggest a reduction in miscarriage odds with high intake of the following food groups: fruit (OR, 0.39; 95% CI, 0.33-0.46), vegetables (OR, 0.59; 95% CI, 0.46-0.76), fruit and vegetables (OR, 0.63; 95% CI, 0.50-0.81), seafood (OR, 0.81; 95% CI, 0.71-0.92), dairy products (OR, 0.63; 95% CI, 0.54-0.73), eggs (OR, 0.81; 95% CI, 0.72-0.90), and cereal (grains) (OR, 0.67; 95% CI, 0.52-0.87). The evidence was uncertain for meat, red meat, white meat, fat and oil, and sugar substitutes. We did not find evidence of an association between adherence to predefined dietary patterns and miscarriage risk. However, a whole diet containing healthy foods as perceived by the trialists, or with a high Dietary Antioxidant Index score (OR, 0.43; 95% CI, 0.20-0.91) may be associated with a reduction in miscarriage risk. In contrast, a diet rich in processed food was demonstrated to be associated with increased miscarriage risk (OR, 1.97; 95% CI, 1.36-3.34)., Conclusion and Relevance: A diet abundant in fruit, vegetables, seafood, dairy, eggs, and grain may be associated with lower miscarriage odds. Further interventional studies are required to accurately assess the effectiveness of periconception dietary modifications on miscarriage risk., Prospero Registration: CRD42020218133., (Copyright © 2023 The Authors. Published by Elsevier Inc. All rights reserved.)

Background: A time lapse system (TLS) is utilized in some fertility clinics with the aim of predicting embryo viability and chance of live birth during IVF. It has been hypothesized that aneuploid embryos display altered morphokinetics as a consequence of their abnormal chromosome complement. Since aneuploidy is one of the fundamental reasons for IVF failure and miscarriage, attention has focused on utilizing morphokinetics to develop models to non-invasively risk stratify embryos for ploidy status. This could avoid or reduce the costs associated with pre-implantation genetic testing for aneuploidy (PGT-A). Furthermore, TLS have provided an understanding of the true prevalence of other dysmorphisms. Hypothetically, the incorporation of morphological features into a model could act synergistically, improving a model's discriminative ability to predict ploidy status., Objective and Rationale: The aim of this systematic review and meta-analysis was to investigate associations between ploidy status and morphokinetic or morphological features commonly denoted on a TLS. This will determine the feasibility of a prediction model for euploidy and summarize the most useful prognostic markers to be included in model development., Search Methods: Five separate searches were conducted in Medline, Embase, PubMed and Cinahl from inception to 1 July 2021. Search terms and word variants included, among others, PGT-A, ploidy, morphokinetics and time lapse, and the latter were successively substituted for the following morphological parameters: fragmentation, multinucleation, abnormal cleavage and contraction. Studies were limited to human studies., Outcomes: Overall, 58 studies were included incorporating over 40 000 embryos. All except one study had a moderate risk of bias in at least one domain when assessed by the quality in prognostic studies tool. Ten morphokinetic variables were significantly delayed in aneuploid embryos. When excluding studies using less reliable genetic technologies, the most notable variables were: time to eight cells (t8, 1.13 h, 95% CI: 0.21-2.05; three studies; n = 742; I2 = 0%), t9 (2.27 h, 95% CI: 0.5-4.03; two studies; n = 671; I2 = 33%), time to formation of a full blastocyst (tB, 1.99 h, 95% CI 0.15-3.81; four studies; n = 1640; I2 = 76%) and time to expanded blastocyst (tEB, 2.35 h, 95% CI: 0.06-4.63; four studies; n = 1640; I2 = 83%). There is potentially some prognostic potential in the degree of fragmentation, multinucleation persisting to the four-cell stage and frequency of embryo contractions. Reverse cleavage was associated with euploidy in this meta-analysis; however, this article argues that these are likely spurious results requiring further investigation. There was no association with direct unequal cleavage in an embryo that progressed to a blastocyst, or with multinucleation assessed on Day 2 or at the two-cell stage. However, owing to heterogeneous results and poor-quality evidence, associations between these morphological components needs to be investigated further before conclusions can be reliably drawn., Wider Implications: This first systematic review and meta-analysis of morphological and morphokinetic associations with ploidy status demonstrates the most useful morphokinetic variables, namely t8, t9 and tEB to be included in future model development. There is considerable variability within aneuploid and euploid embryos making definitively classifying them impossible; however, it is feasible that embryos could be prioritized for biopsy. Furthermore, these results support the mechanism by which algorithms for live birth may have predictive ability, suggesting aneuploidy causes delayed cytokinesis. We highlight significant heterogeneity in our results secondary to local conditions and diverse patient populations, therefore calling for future models to be robustly developed and tested in-house. If successful, such a model would constitute a meaningful breakthrough when accessing PGT-A is unsuitable for couples., (© The Author(s) 2022. Published by Oxford University Press on behalf of European Society of Human Reproduction and Embryology. All rights reserved. For permissions, please email: journals.permissions@oup.com.)

Competing Interests: TIMK reports lecture fees from Berlin-Chemie, Goodlife Healthcare, EXCEMED, Merck, IBSA, and Quidel, and currently serves as the co-chair of the 2023 Guidelines of the American Thyroid Association for the Diagnosis and Management of Thyroid Disease During Preconception, Pregnancy and the Postpartum guideline committee. RD-S serves as the Fertility and Assisted Reproduction working group coordinator of the 2023 Guidelines of the American Thyroid Association for the Diagnosis and Management of Thyroid Disease During Preconception, Pregnancy and the Postpartum guideline committee.

Study Objective: Endometriosis is a recognized cause of pelvic pain in adolescents with menstrual symptoms that significantly affect education, activity, and social interactions. We aim to provide an updated systematic review of the prevalence of endometriosis in adolescents with pelvic pain presenting for gynecological investigation., Data Sources: We searched Medline, Embase, and Cinahl from 2011 to July 2019., Methods of Study Selection: We included cohort studies of adolescents with pelvic pain undergoing gynecological investigation. Two authors independently selected studies and extracted study characteristics and prevalence data. Methodological quality was assessed using the Critical Appraisal Skills Program for cohort studies., Results: This updated systematic review evaluated a total of 19 studies including 1243 symptomatic adolescents. In all, 648 of 1011 (64%) adolescents undergoing laparoscopy were found to have endometriosis. The prevalence ranged from 25% to 100%, with a mean prevalence of 64%. Thirteen studies including 381 participants categorized disease severity using the revised American Society of Reproductive Medicine classification. Among these, 53% of participants (201/381) had stage I, 28% (105/381) had stage II, 20% (76/381) had stage III, and 13% (49/381) had stage IV disease., Conclusions: The prevalence of endometriosis among adolescents with pelvic pain symptoms is high. Endometriosis is treatable, and prompt recognition will help to ensure that adolescents are signposted earlier to appropriate specialists. The management of adolescents with suspected endometriosis should be consistent with best practice guidance. Despite recommendations to increase the awareness and knowledge of endometriosis in adolescence, minimal research has followed., (Copyright © 2020 North American Society for Pediatric and Adolescent Gynecology. Published by Elsevier Inc. All rights reserved.)

Progesterone is essential for the maintenance of pregnancy. Several small trials have suggested that progesterone supplementation may reduce the risk of miscarriage in women with recurrent or threatened miscarriage. Cochrane Reviews summarized the evidence and found that the trials were small with substantial methodologic weaknesses. Since then, the effects of first-trimester use of vaginal micronized progesterone have been evaluated in 2 large, high-quality, multicenter placebo-controlled trials, one targeting women with unexplained recurrent miscarriages (the PROMISE [PROgesterone in recurrent MIScarriagE] trial) and the other targeting women with early pregnancy bleeding (the PRISM [PRogesterone In Spontaneous Miscarriage] trial). The PROMISE trial studied 836 women from 45 hospitals in the United Kingdom and the Netherlands and found a 3% greater live birth rate with progesterone but with substantial statistical uncertainty. The PRISM trial studied 4153 women from 48 hospitals in the United Kingdom and found a 3% greater live birth rate with progesterone, but with a P value of .08. A key finding, first observed in the PROMISE trial, and then replicated in the PRISM trial, was that treatment with vaginal micronized progesterone 400 mg twice daily was associated with increasing live birth rates according to the number of previous miscarriages. Prespecified PRISM trial subgroup analysis in women with the dual risk factors of previous miscarriage(s) and current pregnancy bleeding fulfilled all 11 conditions for credible subgroup analysis. For the subgroup of women with a history of 1 or more miscarriage(s) and current pregnancy bleeding, the live birth rate was 75% (689/914) with progesterone vs 70% (619/886) with placebo (rate difference 5%; risk ratio, 1.09, 95% confidence interval, 1.03-1.15; P=.003). The benefit was greater for the subgroup of women with 3 or more previous miscarriages and current pregnancy bleeding; live birth rate was 72% (98/137) with progesterone vs 57% (85/148) with placebo (rate difference 15%; risk ratio, 1.28, 95% confidence interval, 1.08-1.51; P=.004). No short-term safety concerns were identified from the PROMISE and PRISM trials. Therefore, women with a history of miscarriage who present with bleeding in early pregnancy may benefit from the use of vaginal micronized progesterone 400 mg twice daily. Women and their care providers should use the findings for shared decision-making., (Copyright © 2019 The Author(s). Published by Elsevier Inc. All rights reserved.)

Thyroid autoimmunity (TAI) is prevalent amongst women of reproductive age. TAI describes the presence of circulating anti-thyroid autoantibodies that are targeted against the thyroid, with or without thyroid dysfunction. Thyroid peroxidase antibodies (TPOAb) are the most common anti-thyroid autoantibodies. Around 10% of biochemically euthyroid individuals also have an elevated TPOAb titre. Many studies have linked the presence of TPOAb to adverse maternal and fetal outcomes in pregnancy, in particular miscarriage and pre-term birth, even in the absence of thyroid dysfunction. The causal pathway is poorly understood and few trials have looked to find treatments to reduce adverse outcomes. This review discusses in detail the associated adverse outcomes of TPOAb in pregnancy and the results of trials exploring methods to reduce such outcomes. Recommendations for counselling and monitoring of women with TPOAb and suggested areas for future work are also outlined., (Crown Copyright © 2020. Published by Elsevier Ltd. All rights reserved.)

Competing Interests: T.I.M.K. has received personal fees from Berlin Chemie, Goodlife Healthcare, and Quidel. R.P.P. stated serving as a consultant to Berlin-Chemie AG, Fertility BV, GoodLife, and Institut Biochimique SA.

Background: Vitamin D deficiency has been associated with an increased risk of abnormal pregnancy implantation leading to obstetric complications such as pre-eclampsia and fetal growth restriction. However, the effect of vitamin D on reproductive treatment outcomes in couples undergoing assisted reproductive treatment is poorly understood. This study investigates the association between vitamin D and reproductive treatment outcomes in women undergoing assisted reproductive treatments?, Methods: A prospective cohort study conducted at a large tertiary teaching hospital, United Kingdom. Five hundred women undergoing assisted reproductive treatment were recruited between September 2013 and September 2015. All participants had their serum vitamin D measured and their reproductive treatment outcomes collated. Women were categorised in to three groups: vitamin D replete (> 75 nmol/L), insufficient (50-75 nmol/L) and deficient (< 50 nmol/L) according to Endocrine Society guidance. The primary outcome was live birth. Secondary outcomes included biochemical pregnancy, clinical pregnancy and pregnancy loss rates., Results: Vitamin D deficiency was found in 53.2% (266/500) of participants and vitamin D insufficiency was found in 30.8% (154/500) of participants. Only 16% (80/500) of women were vitamin D replete. The live birth rates for vitamin D deficient, insufficient and replete women were 23.2% (57/246), 27.0% (38/141) and 37.7% (29/77) respectively (p = 0.04). The respective live birth rates for vitamin D deficient, insufficient and replete women were 24.3, 27.1, 34.4% after adjustment for key prognostic factors (p = 0.25)., Conclusions: Vitamin D deficiency and insufficiency are common in women undergoing assisted reproductive treatments. The crude live birth rate achieved in women undergoing assisted reproductive treatments are associated with serum vitamin D, although statistical significance is lost when adjusting for important prognostic variables. Vitamin D deficiency could be an important condition to treat in women considering fertility treatment. A research trial to investigate the benefits of vitamin D deficiency treatment would test this hypothesis., Trial Registration: Clinicaltrials.gov - NCT02187146 .

Introduction: 'Core outcome sets' are an agreed, standardised set of outcomes based on what key stakeholders (clinicians, patients, their partners, researchers, service developers, funding organisations and so on) consider the important outcomes in the management or prevention of a condition. This paper describes the rationale and design for the development of Core Outcome Sets for Miscarriage Trials., Methods and Analysis: Systematic reviews, interviews and focus groups with patients and their partners will be conducted to identify potential core outcomes that will be introduced into a modified Delphi survey. To ensure all key stakeholders are included, patients, partners, clinicians, charities and researchers will be invited to take part in the modified Delphi survey. There will be three rounds of scoring and rescoring during the Delphi survey to reach consensus regarding outcomes to be included in the core set, which will be subsequently refined through face-to-face consensus discussions., Ethics and Dissemination: The use of core outcome sets allows results from different studies to be compared and combined, thereby reducing inconsistency and aiding interpretation of study findings. It also means research is more likely to report relevant outcomes and so can reduce reporting bias. Understanding which outcomes are important to patients has the potential to act as a driver to improve both the quality and cost-effectiveness of miscarriage services., Competing Interests: Competing interests: None declared., (© Article author(s) (or their employer(s) unless otherwise stated in the text of the article) 2017. All rights reserved. No commercial use is permitted unless otherwise expressly granted.)