BACKGROUND While oocyte IVM is practiced sporadically it has not achieved widespread clinical practice globally. However, recently there have been some seminal advances in our understanding of basic aspects of oocyte biology and ovulation from animal studies that have led to novel approaches to IVM. A significant recent advance in IVM technology is the use of biphasic IVM approaches. These involve

BACKGROUND Modern lifestyle has led to an increase in the age at conception. Advanced age is one of the critical risk factors for female-related infertility. It is well known that maternal age positively correlates with the deterioration of oocyte quality and chromosomal abnormalities in oocytes and embryos. The effect of age on endometrial function may be an equally important factor influencing implantation

BACKGROUND Preconception diet is a proposed modifiable risk factor for infertility. However, there is no official guidance for women in the preconception period as to which dietary approaches may improve fertility. OBJECTIVE AND RATIONALE A comprehensive synthesis of the relevant evidence is key to determine the potentially effective dietary patterns and components as well as evidence gaps, and to

BACKGROUND Estrogens regulate disparate female physiological processes, thus ensuring reproduction. Altered estrogen levels and signaling have been associated with increased risks of pregnancy failure and complications, including hypertensive disorders and low birthweight babies. However, the role of estrogens in the periconceptional period and early pregnancy is still understudied. OBJECTIVE AND RATIONALE

BACKGROUND Mammalian reproduction requires the fusion of two specialized cells: an oocyte and a sperm. In addition to producing gametes, the reproductive system also provides the environment for the appropriate development of the embryo. Deciphering the reproductive system requires understanding the functions of each cell type and cell–cell interactions. Recent single-cell omics technologies have provided

BACKGROUND Current knowledge about the consequences of PCOS during the late reproductive years and after menopause is limited. OBJECTIVE AND RATIONALE We performed a systematic review and meta-analysis of data on the pathophysiology, clinical manifestations, diagnosis, prognosis, and treatment of women ≥45 years of age—peri- or postmenopausal—with PCOS. SEARCH METHODS Studies published up to 15 April

BACKGROUND In IVF/ICSI treatment, the process of embryo implantation is the success rate-limiting step. Endometrial scratching has been suggested to improve this process, but it is unclear if this procedure increases the chance of implantation and live birth (LB) and, if so, for whom, and how the scratch should be performed. OBJECTIVE AND RATIONALE This individual participant data meta-analysis (IPD-MA)

Women suffering from absolute uterine factor infertility (AUFI) had no hope of childbearing until clinical feasibility of uterus transplantation (UTx) was documented in 2014 with the birth of a healthy baby. This landmark accomplishment followed extensive foundational work with a wide range of animal species including higher primates. In the present review, we provide a summary of the animal research

BACKGROUND The endometrium is a highly dynamic tissue that undergoes dramatic proliferation and differentiation monthly in order to prepare the uterus for implantation and pregnancy. Intrauterine infection and inflammation are being increasingly recognized as potential causes of implantation failure and miscarriage, as well as obstetric complications later in gestation. However, the mechanisms by which

BACKGROUND A normal chromosomal constitution defined through PGT-A assessing all chromosomes on trophectoderm (TE) biopsies represents the strongest predictor of embryo implantation. Yet, its positive predictive value is not higher than 50–60%. This gap of knowledge on the causes of euploid blastocysts’ reproductive failure is known as ‘the black box of implantation’. OBJECTIVE AND RATIONALE Several

BACKGROUND The number of frozen embryo transfers (FET) has increased dramatically over the past decade. Based on current evidence, there is no difference in pregnancy rates when natural cycle FET (NC-FET) is compared to artificial cycle FET (AC-FET) in subfertile women. However, NC-FET seems to be associated with lower risk of adverse obstetric and neonatal outcomes compared with AC-FET cycles. Currently

BACKGROUND Endometriosis remains a poorly understood disease, despite its high prevalence and debilitating symptoms. The overlap in symptoms and the increased risk of multiple other traits in women with endometriosis is becoming increasingly apparent through epidemiological data. Genetic studies offer a method of investigating these comorbid relationships through the assessment of causal relationships

BACKGROUND The high rates of unintended pregnancy and the ever-growing world population impose health, economic, social, and environmental threats to countries. Expanding contraceptive options, including male methods, are urgently needed to tackle these global challenges. Male contraception is limited to condoms and vasectomy, which are unsuitable for many couples. Thus, novel male contraceptive methods

BACKGROUND Total fertilization failure (TFF) is the failure of all metaphase II oocytes to fertilize in ART cycles. The phenomenon represents a known cause of infertility, affecting 1–3% of ICSI cycles. Oocyte activation deficiency (OAD) is the leading cause of fertilization failure, attributed to sperm- or oocyte-related issues, although until recently little attention has been given to oocyte-related

BACKGROUND It has long been thought that the factors affecting embryo and foetal development were exclusively maternally derived; hence, if issues regarding fertility and embryo development were to arise, the blame has traditionally been placed solely on the mother. An escalating interest in how paternal factors influence embryo development, however, has begun to prove otherwise. Evidence suggests

BACKGROUND Regulated cell death is a fundamental component of numerous physiological processes; spanning from organogenesis in utero, to normal cell turnover during adulthood, as well as the elimination of infected or damaged cells throughout life. Quality control through regulation of cell death pathways is particularly important in the germline, which is responsible for the generation of offspring

BACKGROUND Abnormal uterine bleeding (AUB) has a significant socioeconomic impact since it considerably impacts quality of life. Therapeutic options are frequently based on trial and error and do not target disease aetiology. Pathophysiological insight in this disease is required for the development of novel treatment options. If no underlying cause is found for the AUB (e.g. fibroids, adenomyosis

BACKGROUND Owing to a growing number of young and adolescent Hodgkin lymphoma (HL) survivors, awareness of (long-term) adverse effects of anticancer treatment increases. The risk of impaired reproductive ability is of great concern given its impact on quality of life. There is currently no review available on fertility after childhood HL treatment. OBJECTIVE AND RATIONALE The aim of this narrative

BACKGROUND Primary ciliary dyskinesia (PCD) is a genetic condition affecting the structure and function of sperm flagellum and motile cilia including those in the male and female reproductive tracts. Infertility is a commonly reported feature of PCD, but there is uncertainty as to how best to counsel patients on their fertility prognosis. OBJECTIVE AND RATIONALE This review aimed to summarize the prevalence

BACKGROUND Preimplantation genetic testing (PGT) of embryos developed in vitro requires a biopsy for obtaining cellular samples for the analysis. Signs of cell injury have been described in association with this procedure. Thus, the consequences of the biopsy on obstetric and neonatal outcomes have been the subject of some quantitative analyses, although the reliability of data pooling may be limited

BACKGROUND The early onset of menopause is associated with increased risks of cardiovascular disease and osteoporosis. As a woman's circulating anti-Müllerian hormone (AMH) concentration reflects the number of follicles remaining in the ovary and declines towards the menopause, serum AMH may be of value in the early diagnosis and prediction of age at menopause. OBJECTIVE AND RATIONALE This systematic

BACKGROUND Since the birth of the first baby using IVF technology in 1978, over 10 million children have been conceived via ART. Although most aspects of ARTs were developed in animal models, the introduction of these technologies into clinical practice was performed without comprehensive assessment of their long-term safety. The monitoring of these technologies over time has revealed differences in

BACKGROUND Several GnRH antagonist protocols are currently used during COS in the context of ART treatments; however, questions remain regarding whether these protocols are comparable in terms of efficacy and safety. OBJECTIVE AND RATIONALE A systematic review followed by a pairwise and network meta-analyses were performed. The systematic review and pairwise meta-analysis of direct comparative data

BACKGROUND As in other domains of medicine, high-throughput sequencing methods have led to the identification of an ever-increasing number of gene variants in the fields of both male and female infertility. The increasing number of recently identified genes allows an accurate diagnosis for previously idiopathic cases of female infertility and more appropriate patient care. However, robust evidence

BACKGROUND Rising maternal ages and age-related fertility decline are a global challenge for modern reproductive medicine. Clinicians and researchers pay specific attention to ovarian ageing and hormonal insufficiency in this regard. However, uterine ageing is often left out of the picture, with the majority of reproductive clinicians being close to unanimous on the absence of age-related functional

BACKGROUND Hypergonadotropic hypogonadism is a burdensome complication of classic galactosemia (CG), an inborn error of galactose metabolism that invariably affects female patients. Since its recognition in 1979, data have become available regarding the clinical spectrum, and the impact on fertility. Many women have been counseled for infertility and the majority never try to conceive, yet spontaneous

BACKGROUND Increasing childhood cancer survival rates in recent decades have led to an increased focus on fertility as a long-term complication of cancer treatment. Male childhood cancer survivors often face compromised testicular function as a late effect of chemotherapy exposure, with no well-established options to prevent such damage and subsequent infertility. Despite vincristine being considered

BACKGROUND Increasing numbers of BReast CAncer (BRCA) 1 or 2 pathogenic variant (PV) carriers, who have an inherited predisposition to breast and ovarian cancer, are being identified. Among these women, data regarding the effects of contraception on cancer risks are unclear and various guidelines provide various recommendations. OBJECTIVE AND RATIONALE We aim to optimize counselling regarding contraception

BACKGROUND Numerous studies have reported declines in semen quality and other markers of male reproductive health. Our previous meta-analysis reported a significant decrease in sperm concentration (SC) and total sperm count (TSC) among men from North America–Europe–Australia (NEA) based on studies published during 1981–2013. At that time, there were too few studies with data from South/Central America–Asia–Africa

BACKGROUND Depression and anxiety are highly prevalent among individuals struggling with infertility. Thus, numerous psychological interventions have been adapted to infertility, with the aim of relieving distress as well as increasing pregnancy rates. OBJECTIVE AND RATIONALE This systematic review and meta-analysis aimed to identify all randomized controlled trials (RCTs) evaluating the effect of

BACKGROUND Reproductive tract infection is an important factor leading to male and female infertility. Among female infertility factors, microbial and viral infections are the main factors affecting female reproductive health and causing tubal infertility, ectopic tubal pregnancy and premature delivery. Among male infertility factors, 13-15% of male infertility is related to infection. Defensins are

BACKGROUND Modern reproductive behavior in most developed countries is characterized by delayed parenthood. Older gametes are generally less fertile, accumulating and compounding the effects of varied environmental exposures that are modified by lifestyle factors. Clinicians are primarily concerned with advanced maternal age, while the influence of paternal age on fertility, early development and offspring

BACKGROUND Sexuality has a key impact on quality of life and on reproductive health. Infertility often results in sexual dysfunction. Despite this close association, addressing sexuality is not a standard component of infertility counselling, especially since in most countries sexual medicine is not a core element of specialist training. Even today, many doctors and patients consider discussing sexuality

BACKGROUND Air pollution is both a sensory blight and a threat to human health. Inhaled environmental pollutants can be naturally occurring or human-made, and include traffic-related air pollution (TRAP), ozone, particulate matter (PM) and volatile organic compounds, among other substances, including those from secondhand smoking. Studies of air pollution on reproductive and endocrine systems have

BACKGROUND Folliculogenesis occurs in the highly dynamic environment of the ovary. Follicle cyclic recruitment, neo-angiogenesis, spatial displacement, follicle atresia and ovulation stand out as major events resulting from the interplay between mechanical forces and molecular signals. Morphological and functional changes to the growing follicle and to the surrounding tissue are required to produce

BACKGROUND To provide the optimal milieu for implantation and fetal development, the female reproductive system must orchestrate uterine dynamics with the appropriate hormones produced by the ovaries. Mature oocytes may be fertilized in the fallopian tubes, and the resulting zygote is transported toward the uterus, where it can implant and continue developing. The cervix acts as a physical barrier

BACKGROUND The positive effects of growth hormone (GH) on IVF are often attributed to improvements in oocyte and embryo quality. While emerging evidence emphasizes GH-induced improvements in the endometrium, these results are controversial. OBJECTIVE AND RATIONALE This meta-analysis aimed to evaluate whether GH administration improved endometrial function and reproductive outcomes during IVF cycles

BACKGROUND The key oncogene B-cell lymphoma 6 (BCL6) drives malignant progression by promoting proliferation, overriding DNA damage checkpoints and blocking cell terminal differentiation. However, its functions in the placenta and the endometrium remain to be defined. OBJECTIVE AND RATIONALE Recent studies provide evidence that BCL6 may play various roles in the human placenta and the endometrium.

BACKGROUND Obesity has now been recognized as a high-risk factor for reproductive health. Although remarkable advancements have been made in ART, a considerable number of infertile obese women still suffer from serial implantation failure, despite the high quality of embryos transferred. Although obesity has long been known to exert various deleterious effects on female fertility, the underlying mechanisms

BACKGROUND Lifestyle (dietary and/or physical activity [PA]) modification is recommended as first-line therapy to manage polycystic ovary syndrome (PCOS). Current recommendations are based on healthy lifestyle practices for the general public since evidence for unique lifestyle approaches in PCOS is limited and low quality. OBJECTIVE AND RATIONALE We aimed to synthesize evidence on dietary and PA behaviors

BACKGROUND Meiosis is an essential stage in the life cycle of sexually reproducing species, underlying formation of haploid gametes and serving as the basis of genetic diversity. A central mechanism of meiosis is recombination between homologous chromosomes, during which programmed DNA double-strand breaks (DSBs) are sequentially repaired to form the crossovers essential for faithful chromosomal segregation

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

BACKGROUND Intrauterine insemination with ovarian stimulation (IUI-OS) is a first-line treatment for unexplained infertility. Gonadotrophins, letrozole and clomiphene citrate (CC) are commonly used agents during IUI-OS and have been compared in multiple aggregate data meta-analyses, with substantial heterogeneity and no analysis on time-to-event outcomes. Individual participant data meta-analysis (IPD-MA)

BACKGROUND The beneficial effects of hormonal therapy in stimulating spermatogenesis in patients with non-obstructive azoospermia (NOA) and either normal gonadotrophins or hypergonadotropic hypogonadism prior to surgical sperm retrieval (SSR) is controversial. Although the European Association of Urology guidelines state that hormone stimulation is not recommended in routine clinical practice, a significant

BACKGROUND Offering fertility preservation (FP) prior to gonadotoxic therapy, including cancer care and gender-affirming treatment, is now considered standard of care. Periodically, parents and children disagree about whether to pursue FP. However, it is unknown how often this occurs and how disagreement is handled when it arises. Moreover, there is no clear guidance on how to resolve these difficult

BACKGROUND Globally, the ages at pubertal onset for girls and boys have been decreasing during recent decades, partly attributed to excess body fat accumulation. However, a growing body of literature has recognized that endocrine disrupting chemicals (EDCs) may play an important role in this global trend, but the association has not yet been fully established. OBJECTIVE AND RATIONALE EDCs can interfere

BACKGROUND Several interventions and techniques are suggested to improve the outcome of embryo transfer (ET) in assisted conception. However, there remains no consensus on the optimal practice, with high variations among fertility specialists. OBJECTIVE AND RATIONALE We conducted a comprehensive systematic review and meta-analyses of randomized controlled trials (RCTs) aiming to identify effective

ABSTRACT The pathways of gametogenesis encompass elaborate cellular specialization accompanied by precise partitioning of the genome content in order to produce fully matured spermatozoa and oocytes. Transcription factors are an important class of molecules that function in gametogenesis to regulate intrinsic gene expression programs, play essential roles in specifying (or determining) germ cell fate

BACKGROUND Uterine natural killer cells (uNK) are the most abundant lymphocytes found in the decidua during implantation and in first trimester pregnancy. They are important for early placental development, especially trophoblast invasion and transformation of the spiral arteries. However, inappropriate uNK function has been implicated in reproductive failure, such as recurrent miscarriage (RM) or

BACKGROUND Efficient and safe embryo vitrification techniques have contributed to a marked worldwide increase in the use of elective frozen embryo transfer (FET). Pinpointing the day of ovulation, more commonly by documentation of the LH surge and less commonly by ultrasonography, is crucial for timing of FET in a true natural cycle (t-NC) to maximize the reproductive outcome. OBJECTIVE AND RATIONALE

BACKGROUND An increased prevalence of functional hyperandrogenism—including polycystic ovary syndrome (PCOS)—has been described in women with type 1 diabetes (T1D). However, heterogeneity between studies is frequent, and prevalence rates vary according to different criteria used for the diagnosis of PCOS and the population studied. OBJECTIVE AND RATIONALE We aimed to perform a systematic review and

BACKGROUND The many manipulations and processes used in ART coincide with the timing of epigenetic reprogramming and imprinting during female gametogenesis and pre-implantation embryo development, leading to concerns that the actual ART could negatively affect epigenetic reprogramming and imprinting in gametes and early embryos. A growing body of literature suggests that ART may affect epigenetic marks

BACKGROUND Although the immune system intuitively must have an important role in embryo implantation and in the achievement of a pregnancy, the molecular details have for long been controversial. The role of the human leukocyte antigen (HLA) system has been debated. The unique HLA expression profile of the HLA Class Ia molecule HLA-C and the HLA Class Ib molecules HLA-E, HLA-F and HLA-G at the feto–maternal

BACKGROUND Uterine leiomyomas, also known as uterine fibroids or myomas, are the most common benign gynecological tumors and are found in women of reproductive and postmenopausal age. There is an exceptionally high prevalence of this tumor in women by the age of 50 years. Black women are particularly affected, with an increased incidence, earlier age of onset, larger and faster growing fibroids and

BACKGROUND Female patients undergoing anticancer treatment are at elevated risk of adverse ovarian outcomes including infertility and premature ovarian insufficiency (POI), which is associated with short- and long-term health risks. Anti-Müllerian hormone (AMH) is a key biomarker of ovarian reserve, but its role prior to and after cancer treatment is less well understood. OBJECTIVE AND RATIONALE To

BACKGROUND According to the Developmental Origins of Health and Disease (DOHaD) hypothesis, environmental changes taking place during early maturational periods may alter normal development and predispose to the occurrence of diverse pathologies later in life. Indeed, adverse conditions during these critical developmental windows of high plasticity have been reported to alter the offspring developmental