Our understanding of the intracrine (or local) regulation of estrogen and other steroid synthesis and degradation expanded in the last decades, also thanks to recent technological advances in chromatography mass-spectrometry. Estrogen responsive tissues and organs are not passive receivers of the pool of steroids present in the blood but they can actively modify the intra-tissue steroid concentrations. This allows fine-tuning the exposure of responsive tissues and organs to estrogens and other steroids in order to best respond to the physiological needs of each specific organ. Deviations in such intracrine control can lead to unbalanced steroid hormone exposure and disturbances. Through a systematic bibliographic search on the expression of the intracrine enzymes in various tissues, this review gives an up-to-date view of the intracrine estrogen metabolisms, and to a lesser extent that of progestogens and androgens, in the lower female genital tract, including the physiological control of endometrial functions, receptivity, menopausal status and related pathological conditions. An overview of the intracrine regulation in extra gynecological tissues such as the lungs, gastrointestinal tract, brain, colon and bone is given. Current therapeutic approaches aimed at interfering with these metabolisms and future perspectives are discussed.

Is embryo culture media used during an IVF/ICSI treatment associated with differences in growth, body composition and cardiovascular development as determined in 9-year-old singleton IVF children? The choice of in vitro culture medium for human embryos is associated with differences in body weight, BMI, truncal adiposity, waist circumference and waist/hip ratio at the age of 9, while no significant differences were observed in cardiovascular development. Children born after IVF/ICSI have an increased risk of low birthweight, which is correlated with a higher risk of cardiovascular diseases. Some studies show that IVF children exhibit a significantly higher systolic and diastolic blood pressure and higher fasting glucose levels compared to naturally conceived children. After alternating assignment to G1™ Version 3 (Vitrolife) or K-SICM (Cook) embryo culture media, birthweight of the resulting children was significantly higher in the Vitrolife group and they remained heavier during the first 2 years of life. In this observational cohort study (MEDIUM-KIDS), parents of singletons from a previous study were approached for further follow-up after the ninth birthday of their child. The singletons were born after fresh embryo transfer of cleavage stage embryos resulting from an IVF/ICSI treatment performed between July 2003 and December 2006 in our clinic, when two different culture media were used alternately: either G1™ Version 3 (Vitrolife) or K-SICM (Cook). Follow-up measurements were performed between March 2014 and December 2016. Parents were invited to attend our clinic with their child for a single visit lasting ~2.5 h. Two experienced clinicians performed all measurements as part of the MEDIUM-KIDS study in a standardized way. Height and weight of the child was measured using calibrated scales, 4-point skinfold thickness measurements were measured in triplicate and waist and hip circumference were measured using a tape measure. The following cardiovascular parameters were measured in a standardized way: blood pressure, heart rate and endothelial function by skin laser-Doppler with iontophoresis using vasodilatory drugs. Cortisol and cortisone concentrations in hair were measured. A blood sample was taken after an overnight fast for insulin, glucose, TSH and lipid analysis. Blood samples of the IVF children were compared with a non-IVF control group. Differences between culture medium groups were analysed by Student's t-test and effects of confounders were analysed using multivariable regression analysis. Of the 294 eligible children (168 Vitrolife and 126 Cook), 136 children (75 Vitrolife and 61 Cook) participated in the study. Baseline characteristics of the participating children from the Vitrolife and Cook group were similar. Birthweight was higher in the Vitrolife group, in keeping with the full cohort. After correction for confounders, the difference in weight and BMI attributable to culture medium was 1.58 kg (95% CI: 0.01-3.14) and 0.84 kg/m2 (95% CI: 0.02-1.67), respectively, with the Vitrolife children being heavier. Height and height corrected for age and gender (SDS scores) were similar in both groups. Furthermore, waist circumference was significantly higher in the Vitrolife group with a corrected difference of 3.21 cm (95%CI: 0.60-5.81) leading to a 0.03 increase (95% CI: 0.01-0.05) in waist/hip ratio. Subscapular skinfolds combined with suprailiacal skinfolds (defined as truncal adiposity), was also significantly higher in Vitrolife children (adjusted difference 3.44 cm [95% CI: 0.27-6.62]). Both systolic (adj. beta 0.364 [95% CI: -2.129 to 2.856],) and diastolic (adj. beta 0.275 [95% CI: -2.105 to 2.654]) blood pressures (mmHg) were comparable for the two groups. After an overnight fast, cholesterol, glucose, insulin, low and high-density lipoprotein, triglycerides and TSH were normal and similar in the two groups. Endothelial function in the microcirculation was compared by using maximum perfusion units corrected for the baseline value as a measure for vasodilatory capacity. There were no significant differences between the two groups. Cortisol and cortisone concentration in hair samples were comparable. A limitation of the original study was its pseudo-randomized design. This and the dwindling enthusiasm of families for participation (47.7% after 9 years) prevent us from drawing robust causal conclusions from the observed association. Nevertheless, to date this is oldest cohort of IVF/ICSI children where culture medium was allocated alternatingly and used in a blinded setting, to be studied. We believe that our participants are representative for the full cohort. The current number of participants was sufficient to rule out differences as little as 3 mmHg in systolic and diastolic blood pressures. This study underlines the importance of structured follow-up of IVF/ICSI children to further elucidate possible long-term health effects. Health professionals and culture medium manufacturers should be aware that small changes in culture conditions and culture medium composition for the early embryo can have long-term health effects. The similar cardiovascular results for the two groups are reassuring but the children may still be too young to detect differences in cardiovascular development. Prolonged follow-up and structured investigations up until adulthood are necessary to gain more insight and reassurance in the cardiovascular development of IVF offspring, although long-term follow-up will become more complicated by confounding life-style and environmental factors possibly influencing development. The study was financially supported by the March of Dimes (Grant number #6-FY13-153). The sponsor of the study had no role in study design, data collection, data analysis, data interpretation or writing of the report. The authors have no conflicts of interest to declare. NTR4220.

The endometrial microbiota composition may be associated with implantation success. However, a ‘core’ composition has not yet been defined. This exploratory study analysed the endometrial microbiota by 16S rRNA sequencing (V1–V2 region) of 141 infertile women whose first IVF/ICSI cycle failed and compared the microbiota profiles of women with and without a live birth within 12 months of follow-up, and by infertility cause and type. Lactobacillus was the most abundant genus in the majority of samples. Women with a live birth compared to those without had significantly higher Lactobacillus crispatus relative abundance (RA) (p = 0.029), and a smaller proportion of them had ≤ 10% L. crispatus RA (42.1% and 70.4%, respectively; p = 0.015). A smaller proportion of women in the male factor infertility group had ≤ 10% L. crispatus RA compared to women in the unexplained and other infertility causes groups combined (p = 0.030). Women with primary infertility compared to secondary infertility had significantly higher L. crispatus RA (p = 0.004); lower proportions of them had ≤ 10% L. crispatus RA (p = 0.009) and > 10% Gardnerella vaginalis RA (p = 0.019). In conclusion, IVF/ICSI success may be associated with L. crispatus RA and secondary infertility with endometrial dysbiosis, more often than primary infertility. These hypotheses should be tested in rigorous well-powered longitudinal studies.

Background: Turner syndrome (TS) is accompanied with premature ovarian insufficiency. Oocyte vitrification is an established method to preserve fertility. However, data on the oocyte yield in women with TS who vitrify their oocytes and the return rate to utilize the oocytes are scarce. Methods: Retrospective multicenter cohort study. Data was collected from medical records of women with TS who started oocyte vitrification between 2010 and 2021. Results: Thirty-three women were included. The median cumulative number of vitrified oocytes was 20 per woman. Complications occurred in 4% of the cycles. Significant correlations were found between the cumulative number of vitrified oocytes and AMH (r = 0.54 and p < 0.01), AFC (r = 0.49 and p < 0.01), percentage of 46,XX cells (r = 0.49 and p < 0.01), and FSH (r = −0.65 and p < 0.01). Spontaneous (n = 8) and IVF (n = 2) pregnancies occurred in 10 women ± three years after vitrification. So far, none of the women have returned to utilize their vitrified oocytes. Conclusions: Oocyte vitrification is a feasible fertility preservation option for women with TS, particularly in those with 46,XX cell lines or sufficient ovarian reserve. Multiple stimulation cycles are recommended to reach an adequate number of vitrified oocytes for pregnancy. It is too early to draw conclusions about the utilization of vitrified oocytes in women with TS.

Introduction Women with repeated implantation failure (RIF) and unexplained recurrent miscarriage (RM) are proposed to be at opposite ends of the implantation spectrum, with RM representing an overly receptive endometrium (implantation of genetically aberrant or poor-quality embryos) versus RIF representing an overly selective endometrium (no implantation even with good quality embryos). In both cases, often no explanation for reproductive failure can be found and although promising add-on treatments have been introduced, therapeutic options are frequently limited to supportive care. Both RM and RIF are multifactorial and research indicates that the interplay between steroidogenesis, uterine natural killer (uNK) cells and the microbiome determine the capacity of the endometrium to be a biosensor for invading embryos. Our objective is to elucidate whether there is a difference in endometrial receptivity parameters (ie, steroid metabolism, uNK cells and the microbiome) between women aged 18–38 years with reproductive failure (RIF and RM), and fertile controls. Methods and analysis Single-centre, observational cohort study. Endometrial biopsies, vaginal swabs and peripheral blood will be collected during the window of implantation and menstrual blood in the subsequent menstruation. The study parameters are the steroid profile (steroid levels and mRNA levels, protein expression and activity of steroid enzymes) in endometrial tissue and peripheral blood, as well as the activating or inhibitory phenotype of uNK cells based on receptor expression in menstrual blood and endometrial tissue and determination of the vaginal and endometrial microbiome using the inter spacer bacterial profiling technique. Ethics and dissemination The protocol is approved by the local medical ethical review committee at the Maastricht University Medical Centre. Findings from this study will be shared with the academic and medical community and the patient organisations to optimise and individualise medical care of patients with implantation failure and miscarriages. Trial registration number NTR7571, registered 28 February 2019.

To study the relationship between the steroid concentration in the endometrium, in serum, and the gene expression level of steroid-metabolizing enzymes in the context of endometrial receptivity in in vitro fertilization (IVF) patients. Case-control study of 40 IVF patients recruited in the SCRaTCH study (NTR5342), a randomized controlled trial investigating pregnancy outcome after "endometrial scratching." Endometrial biopsies and serum were obtained from patients with a first failed IVF cycle randomized to the endometrial scratch in the midluteal phase of the natural cycle before the next fresh embryo transfer during the second IVF cycle. University hopsital. Twenty women with clinical pregnancy were compared with 20 women who did not conceive after fresh embryo transfer. Cases and controls were matched for primary vs. secondary infertility, embryo quality, and age. None. Steroid concentrations in endometrial tissue homogenates and serum were measured with liquid chromatography-mass spectrometry. The endometrial transcriptome was profiled by RNA-sequencing, followed by principal component analysis and differential expression analysis. False discovery rate-adjusted and log-fold change >|0.5| were selected as the threshold for differentially expressed genes. Estrogen levels were comparable in both serum (n = 16) and endometrium (n = 40). Androgens and 17-hydroxyprogesterone were higher in serum than that in endometrium. Although steroid levels did not vary between pregnant and nonpregnant groups, subgroup analysis of primary women with infertility showed a significantly lower estrone concentration and estrone:androstenedione ratio in serum of the pregnant group (n = 5) compared with the nonpregnant group (n = 2). Expression of 34 out of 46 genes encoding the enzymes controlling the local steroid metabolism was detected, and estrogen receptor β gene was differentially expressed between pregnant and nonpregnant women. When only the primary infertile group was considered, 28 genes were differentially expressed between pregnant and nonpregnant women, including HSD11B2, that catalyzes the conversion of cortisol into cortisone. Steroidomic and transcriptomic analyses show that steroid concentrations are regulated by the local metabolism in the endometrium. Although no differences were found in endometrial steroid concentration in the pregnant and nonpregnant IVF patients, primary women with infertility showed deviations in steroid levels and gene expression, indicating that a more homogeneous patient group is required to uncover the exact role of steroid metabolism in endometrial receptivity. The study was registered in the Dutch trial registry (www.trialregister.nl), registration number NL5193/NTR5342, available at https://trialsearch.who.int/Trial2.aspx?TrialID=NTR6687. The date of registration is July 31, 2015. The first enrollment is on January 1, 2016.