The role of steroid hormones in ART

Deciphering the role of PGRMC2 in the human endometrium during the menstrual cycle and in vitro decidualization using an in vitro approach

STUDY QUESTION

What is the human endometrial non-classical progesterone receptor (PGR) membrane component 2 (PGRMC2) expression pattern throughout the menstrual cycle and what role does it play during decidualization?

SUMMARY ANSWER

Endometrial PGRMC2 expression fluctuates during the human menstrual cycle and is abundantly expressed in human endometrial stromal cells (hEnSCs) during in vitro decidualization, process where PGRMC2 is involved in embryo implantation-related pathways.

WHAT IS KNOWN ALREADY

The endometrial response to progesterone is mediated by the classical and non-classical PGRs. We previously demonstrated that PGR membrane component 1 (PGRMC1) is critical for endometrial function, embryo implantation, and future placentation, however, the role(s) of PGRMC2, which is structurally similar to PGRMC1, have not been studied in the human endometrium.

STUDY DESIGN, SIZE, DURATION

This prospective study comprehensively evaluated the endometrial expression of PGRMC2 throughout the human menstrual cycle and during in vitro decidualization of hEnSCs (isolated from 77 endometrial biopsies that were collected from 66 oocyte donors), using immunohistochemistry, RT-qPCR, western blot, transcriptomic, and proteomic analyses. In addition, functional analysis was carried out to validate the implication of PGRMC2 in hEnSCs during embryo invasion using an in vitro outgrowth model.

PARTICIPANTS/MATERIALS, SETTING, METHODS

In vitro decidualization of hEnSCs was induced using co-treatment with cAMP and medroxyprogesterone 17-acetate progestin, and evaluated by measuring prolactin by ELISA and F-actin immunostaining. RT-qPCR was employed to compare expression with other PGRs. To reveal the function of PGRMC2 during the decidualization process, we specifically knocked down PGRMC2 with siRNAs and performed RNA-seq and quantitative proteomics techniques (SWATH-MS). The common differentially expressed genes (DEGs) and proteins (DEPs) were considered for downstream functional enrichment analysis. Finally, to verify its implication in the trophoblast invasion, an outgrowth model was carried out where hEnSCs with silenced PGRMC2 were co-cultured with human trophoblastic spheroids (JEG-3) following in vitro decidualization.

MAIN RESULTS AND THE ROLE OF CHANCE

In contrast to PGRMC1 and classical PGRs, endometrial PGRMC2 gene expression was significantly lower during the late- versus mid-secretory phase (P < 0.05). Accordingly, the elevated PGRMC2 protein abundance observed in the endometrial epithelial glands throughout the menstrual cycle dropped in the late secretory phase, when abundance decreased in all endometrial compartments. Nevertheless, PGRMC2 protein increased during the mid-secretory phase in stromal and glandular cells, and PGRMC2 mRNA (P < 0.0001) and protein (P < 0.001) levels were significantly enhanced in the membranes/organelles of decidualized hEnSCs, compared to non-decidualized hEnSCs. Notably, PGRMC1 and PGRMC2 mRNA were significantly more abundant than classical PGRs throughout menstrual cycle phases and in decidualized and non-decidualized hEnSCs (P < 0.05). RNA-seq and proteomics data revealed 4687 DEGs and 28 DEPs, respectively, in decidualized hEnSCs after PGRMC2 silencing. While functional enrichment analysis showed that the 2420 upregulated genes were mainly associated with endoplasmic reticulum function, vesicular transport, morphogenesis, angiogenesis, cell migration, and cell adhesion, the 2267 downregulated genes were associated with aerobic respiration and protein biosynthesis. The protein enrichment analysis showed that 4 upregulated and 24 downregulated proteins were related to aerobic respiration, cellular response, metabolism, localization of endoplasmic reticulum proteins, and ribonucleoside biosynthesis routes. Finally, PGRMC2 knockdown significantly compromised the ability of the decidualized hEnSCs to support trophoblast expansion in an outgrowth model (P < 0.05).

LARGE-SCALE DATA

Transcriptomic data are available via NCBI's Gene Expression Omnibus (GEO) under GEO Series accession number GSE251843 and proteomic data via ProteomeXchange with identifier PXD048494.

LIMITATIONS, REASONS FOR CAUTION

The functional analyses were limited by the discrete number of human endometrial biopsies. A larger sample size is required to further investigate the potential role(s) of PGRMC2 during embryo implantation and maintenance of pregnancy. Further, the results obtained in the present work should be taken with caution, as the use of a pure primary endometrial stromal population differentiated in vitro does not fully represent the heterogeneity of the endometrium in vivo, nor the paracrine communications occurring between the distinct endometrial cell types.

WIDER IMPLICATIONS OF THE FINDINGS

The repression of endometrial PGRMC2 during the late- versus mid-secretory phase, together with its overexpression during decidualization and multiple implications with embryo implantation not only highlighted the unknown roles of PGRMC2 in female reproduction but also the potential to exploit PGRMC2 signaling pathways to improve assisted reproduction treatments in the future.

STUDY FUNDING/COMPETING INTEREST(S)

This research was funded by Instituto de Salud Carlos III (ISCIII) granted to F.D. (PI20/00405 and PI23/00860), co-funded by the European Union. Y.M.-L. was supported by a predoctoral research grant from Generalitat Valenciana (ACIF/2019/262). R.G.-M. was supported by Generalitat Valenciana (CIAPOT/2022/15). P.d.C. was supported by a predoctoral grant for training in research into health (PFIS FI20/00086) from the Instituto de Salud Carlos III. I.D.-H. was supported by the Spanish Ministry of Science, Innovation and Universities (FPU18/01550). A.P. was supported by the Instituto de Salud Carlos III (PFIS FI18/00009). This research was also supported by IVI Foundation-RMA Global (1911-FIVI-103-FD). The authors declare no conflict of interest.

Establishment of Murine Pregnancy Requires the Promyelocytic Leukemia Zinc Finger Transcription Factor

Using an established human primary cell culture model, we previously demonstrated that the promyelocytic leukemia zinc finger (PLZF) transcription factor is a direct target of the progesterone receptor (PGR) and is essential for progestin-dependent decidualization of human endometrial stromal cells (HESCs). These in vitro findings were supported by immunohistochemical analysis of human endometrial tissue biopsies, which showed that the strongest immunoreactivity for endometrial PLZF is detected during the progesterone (P4)-dominant secretory phase of the menstrual cycle. While these human studies provided critical clinical support for the important role of PLZF in P4-dependent HESC decidualization, functional validation in vivo was not possible due to the absence of suitable animal models. To address this deficiency, we recently generated a conditional knockout mouse model in which PLZF is ablated in PGR-positive cells of the mouse (Plzf d/d). The Plzf d/d female was phenotypically analyzed using immunoblotting, real-time PCR, and immunohistochemistry. Reproductive function was tested using the timed natural pregnancy model as well as the artificial decidual response assay. Even though ovarian activity is not affected, female Plzf d/d mice exhibit an infertility phenotype due to an inability of the embryo to implant into the Plzf d/d endometrium. Initial cellular and molecular phenotyping investigations reveal that the Plzf d/d endometrium is unable to develop a transient receptive state, which is reflected at the molecular level by a blunted response to P4 exposure with a concomitant unopposed response to 17-β estradiol. In addition to a defect in P4-dependent receptivity, the Plzf d/d endometrium fails to undergo decidualization in response to an artificial decidual stimulus, providing the in vivo validation for our earlier HESC culture findings. Collectively, our new Plzf d/d mouse model underscores the physiological importance of the PLZF transcription factor not only in endometrial stromal cell decidualization but also uterine receptivity, two uterine cellular processes that are indispensable for the establishment of pregnancy.

What Do We Know about Classical and Non-Classical Progesterone Receptors in the Human Female Reproductive Tract? A Review

The progesterone hormone regulates the human menstrual cycle, pregnancy, and parturition by its action via the different progesterone receptors and signaling pathways in the female reproductive tract. Progesterone actions can be exerted through classical and non-classical receptors, or even a combination of both. The former are nuclear receptors whose activation leads to transcriptional activity regulation and thus in turn leads to slower but long-lasting responses. The latter are composed of progesterone receptors membrane components (PGRMC) and membrane progestin receptors (mPRs). These receptors rapidly activate the appropriate intracellular signal transduction pathways, and they can subsequently initiate specific cell responses or even modulate genomic cell responses. This review covers our current knowledge on the mechanisms of action and the relevance of classical and non-classical progesterone receptors in female reproductive tissues ranging from the ovary and uterus to the cervix, and it exposes their crucial role in female infertility.

Key to Life: Physiological Role and Clinical Implications of Progesterone

The most recent studies of progesterone research provide remarkable insights into the physiological role and clinical importance of this hormone. Although the name progesterone itself means "promoting gestation", this steroid hormone is far more than a gestational agent. Progesterone is recognized as a key physiological component of not only the menstrual cycle and pregnancy but also as an essential steroidogenic precursor of other gonadal and non-gonadal hormones such as aldosterone, cortisol, estradiol, and testosterone. Based on current findings, progesterone and novel progesterone-based drugs have many important functions, including contraception, treatment of dysfunctional uterine bleeding, immune response, and prevention of cancer. Considering the above, reproduction and life are not possible without progesterone; thus, a better understanding of this essential molecule could enable safe and effective use of this hormone in many clinical conditions.

Patterns of sex hormone receptor expression in stimulated endometrium from oocyte donors

In patients with high serum E₂ embryo transfer is often postponed, as high E₂ levels adversely affect embryo transfer outcome. We aimed to determine if stratified serum oestradiol (E₂) and progesterone (P₄) levels differentially affect endometrial histology and endometrial oestrogen and progesterone receptor protein levels. Endometrial biopsies were collected from oocyte donors. Samples were divided based on peak serum E₂ levels into three groups: (i) low-E₂ (n = 33) E₂≤2999pg/mL; (ii) mid-E₂ (n = 40) E₂ 3000-4999 pg/mL; and (iii) high-E₂ (n = 15) E₂≥5000 pg/mL. Oestrogen receptor alpha (ERα) and progesterone receptors A and B (PR) protein levels in endometrial stroma (S), glandular (GE) and luminal (LE) epithelia were assessed by immunohistochemistry. Samples in high-E₂ group demonstrated strongest association with accelerated endometrial maturation (2 (1-2); 2 (1-3); and 3 (2.8-3) median days of advancement of endometrial maturation respectively in low, mid, high-E₂ groups, p = 0.046). There were significant differences in ERα and PR immunoexpression in S, GE and LE among the groups (p < 0.05). Higher E₂ levels were associated with decreased ERα expression (p < 0.017) in GE and LE, and increased PR expression in S and GE (p < 0.011 and p < 0.0001, respectively). Higher serum E₂ levels were associated with impaired endometrial steroid hormone receptor expression, higher serum P₄ and more advancement of endometrial maturation.

The intrauterine perfusion of granulocyte-colony stimulating factor (G-CSF) before frozen-thawed embryo transfer in patients with two or more implantation failures

The objective of this study was to investigate the clinical benefits of intrauterine perfusion with G-CSF in patients undergoing a frozen-thawed embryo transfer (FET) after at least two previous implantation failures. This was a prospective, randomized, single-blind study. The intervention group received an intrauterine infusion of G-CSF whereas the placebo group was given an intrauterine infusion of physiological saline before embryo transfer. A third (control) group did not receive an intrauterine infusion prior to embryo transfer. The clinical pregnancy rates of both the intervention and placebo group were significantly higher than that in the control group (p < 0.05). But the miscarriage rates of the G-CSF were significantly lower than those of the other two groups (p < 0.05). The intrauterine infusion of G-CSF before frozen-thawed embryo transfer significantly reduced miscarriage rates and improve the live birth rates. While intrauterine perfusion with physiological saline did not reduce miscarriage rates.

The association between treatment parameters on the day of gonadotropin-releasing hormone antagonist initiation during a flexible protocol and oocyte maturation rate

This study aimed to evaluate the effects of different treatment parameters on the day of GnRH antagonist initiation on oocyte maturation rate. We performed a retrospective cohort study of women aged ≤ 38 who underwent their first IVF-ICSI treatment using a flexible GnRH antagonist protocol in a single university-affiliated medical center during 2005-2015. Treatment parameters of three groups of oocyte maturation rates (<60%, 60-90%,>90%) were compared. Multivariate analysis was conducted to detect an association between treatment parameters on the day of GnRH antagonist initiation and oocyte maturation rate. The cohort included 458 patients, of whom 180 (39%) had a high oocyte maturation rate (≥90%), 211 (46%) had an oocyte maturation rate between 60-90% and 67 (15%) had a low maturation rate (≤60%). Women with a high maturation rate had longer duration of treatment (10.3 ± 2.9 days vs. 9.6 ± 2.5 vs. 9.5 ± 3.2, P = 0.019), lower levels of estradiol (1985 ± 1357 vs. 2406 ± 1666 vs. 2325 ± 1811, P = 0.027) and lower estradiol/maximal follicular diameter ratio on the day of GnRH antagonist initiation (137 ± 89 vs. 165 ± 103 vs. 163 ± 125, P = 0.019) as compared to women with medium and low maturation rates, respectively. Using linear regression multivariate analysis, lower estradiol and lower estradiol/maximal follicular diameter ratio on GnRH antagonist initiation day were associated with higher oocyte maturation rate. Further prospective studies to determine the best timing for GnRH antagonist initiation are needed.

Bisphenol A affects estradiol metabolism by targeting CYP1A1 and CYP19A1 in human placental JEG-3 cells

Estradiol, in some way or another, plays a critically important physiologic role in the establishment and maintenance of pregnancy. This study was designed to investigate whether BPA affects the estradiol level of human placental JEG-3 cells, which may contribute to insights into the reproductive toxicity and endocrine disruption of BPA. The JEG-3 cells were treated with increasing concentrations of BPA (0.1 to 50 μM). We observed that BPA significantly reduced estradiol level of JEG-3 cells in a dose-dependent manner, which was accompanied by an increase in CYP1A1 protein level and an inhibition of CYP19A1 protein level. Additionally, by lentiviral transduction, we determined that estradiol level of JEG-3 cells over-expressing CYP1A1 gene was notably decreased and the decrease was of 84.9% compared to the control. Meanwhile, estradiol was almost undetectable in CYP19A1 knockdown group. On the contrary, the group with over-expression of CYP19A1 gene increased estradiol level by 8.6 fold while the CYP1A1 knockdown group increased by 5.6 fold. In summary, our research clearly showed that BPA alters JEG-3 estradiol synthesis and catabolism due to its action on CYP1A1 and CYP19A1 protein levels and may interfere with the normal process of placenta formation and embryonic development during early pregnancy.

Anti-Müllerian hormone and progesterone levels in human follicular fluid are predictors of embryonic development

BACKGROUND

Human follicular fluid is an intricate biological fluid contributing to the developing oocyte microenvironment. Accumulating evidence suggests that sex hormones present in follicular fluid (FF) may play an important role in regulating oocyte developmental potential. The aim of this study was to determine if anti-Müllerian hormone (AMH) and progesterone (P4) levels in FF are correlated with oocyte quality as defined by subsequent embryonic development.

METHODS

This was a prospective cohort study of 88 women undergoing IVF/ICSI at a university associated fertility clinic. Follicular fluid was collected from the first follicle aspirated at the time of oocyte retrieval. The corresponding oocyte was individually cultured in order to track its developmental outcome. FF-AMH and P4 concentrations from follicles where the oocyte fertilised normally and developed into a blastocyst on day 5 (Group 1: BLAST, n = 23) were compared with FF from follicles where the oocyte fertilised normally but failed to reach blastocyst stage by day 5 (Group 2: FERT, n = 19). No significant differences were observed between the two groups in terms of maternal age, body mass index, previous live births, previous pregnancy loss, number of antral follicles, number of oocytes recovered, IVF:ICSI ratio or percentage of recovered oocytes that fertilised.

RESULTS

FF-AMH and P4 levels were significantly increased in Group 1: BLAST compared to Group 2: FERT (P = 0.007 and P = 0.013 respectively). Twenty-one FF samples had an AMH level > 15 pmol/L, of which 17 related to oocytes that progressed to blastocyst stage, providing a positive prediction value (PPV) of 76.96%. Eleven FF samples had a P4 level > 60 mg/ml, of which 10 progressed to blastocyst stage, providing a PPV of 90.99%. Six samples had an AMH level > 15 pmol/L and a P4 level > 60 mg/ml, of which 100% progressed to blastocyst stage, providing a PPV of 96.83%.

CONCLUSIONS

FF-AMH and P4 levels from individual follicles can accurately predetermine subsequent embryonic development. Combining follicular fluid analysis with routine morphological assessment, could allow for a more accurate and sensitive method of determining embryonic developmental competence.

Serum estradiol level change after human chorionic gonadotropin administration had no correlation with live birth rate in IVF cycles

OBJECTIVE

To investigate the correlation between the estradiol (E2) level change after hCG administration and the live birth rate in GnRH agonist long or short protocols, and to explore the possible factors related to E2 dynamics after hCG administration during controlled ovarian hyperstimulation (COH).

STUDY DESIGN

A retrospective analysis was performed on 2868 patients who received IVF/intracytoplasmic sperm injection (ICSI) treatment with GnRH agonist long or short protocol. The patients were divided into three groups according to their serum E2 changes after hCG administration, and the live birth rates were compared among groups. The area under the receiver operating characteristic (ROC) curve was calculated to assess the predictive value of E2 change for the probability of live birth. Logistic regression analysis was also applied to exclude interference from various confounding factors. Finally, multivariate regression analysis was conducted to assess factors related to the E2 change after hCG administration.

RESULTS

No significant difference was observed in live birth rates (4.26%, 36.38% or 30.81% in long protocol (P=0.697); 25.81%, 26.71% or 30.81% in short protocol (P=0.697)) among patients with increasing, plateauing or decreasing E2 responses after hCG administration. The area under the ROC curve for the E2 change in prediction of live birth rate was 0.506 in long protocol, or 0.524 in short protocol. Logistic regression analysis showed that the serum E2 change after hCG administration had no correlation with live birth rate. Multivariate regression analysis showed that the percentage of mature follicles (larger than 14mm) and the duration of stimulation negatively correlated with the E2 change after hCG administration.

CONCLUSIONS

In GnRH agonist cycles, the serum E2 change after hCG administration had no correlation with live birth rate in fresh embryo transfer cycles, and this change negatively correlated with the percentage of mature follicles on the day of hCG administration.

Serum estradiol as a predictor of success of in vitro fertilization

AIM

The aim of this study was to assess the role of total serum estradiol on the day of injection HCG, estradiol per mature follicle, and estradiol per oocytes retrieved (OR) on clinical pregnancy rate (CPR) and oocyte/embryo quality in assisted reproduction.

MATERIALS AND METHODS

A retrospective review of 342 in vitro fertilization cycles with normal ovarian reserve in women who underwent long GnRH agonist protocol was included. The outcomes assessed are number of OR, number of mature oocytes (MO), number of oocytes fertilized (FO), fertilization rate, number of embryos cleaved (EC), cleavage rate (CR), number of Grade I embryos (E), number of cryopreserved embryos (CPE), and CPR. The Estradiol/follicle ratio (E2/fol) was defined as estradiol level per mature follicle >14 mm in diameter. Estradiol/oocyte (E2/O) ratio was defined as estradiol level per OR. These two ratios were categorized by the 25th percentile into four groups.

RESULTS

A positive correlation was seen between E2/fol and OR (r = .334, p value = .0001), MO (r = .335, p value = .0001), FO (r = .222, p value = .002), and CPE (r = .289, p value = .0001). Increased CPR was seen in Group C (E2/fol = 200-299.99) compared to Group A, B, and D (p value = .033). With E2/O ratio, negative correlation was seen between E2/O and OR (r = -.281, p value = .002), MO (r = -.296, p value = .008), FO (r = -.220, p value = .003), EC (r = -.211, p value = .004), Grade 1 embryo (r = -.216, p value = .001), and CPE (r = -.206, p value = .005). No difference in FR, CR, or CPR was seen. No difference was seen in CPR with total serum estradiol.

CONCLUSIONS

In conclusion, serum estradiol is an important determinant of IVF success. While total serum estradiol does not exert any positive or negative influence on IVF outcome, estradiol per mature follicle and retrieved oocytes do have an impact. Pregnancy rate is better when E2/fol is between 200 and 299.99 pg/ml. Also, increasing serum E2/fol positively correlates with better oocytes and embryo quality. In contrast, E2/O negatively correlates with oocytes and embryo quality parameters.

Role of nuclear receptors in blastocyst implantation

The regulation of blastocyst implantation in the uterus is orchestrated by the ovarian hormones estrogen and progesterone. These hormones act via their nuclear receptors to direct the transcriptional activity of the endometrial compartments and create a defined period in which the uterus is permissive to embryo implantation termed the "window of receptivity". Additional members of the nuclear receptor family have also been described to have a potential role in endometrial function. Much of what we know about the function of these nuclear receptors during implantation we have learned from the use of mouse models. Transgenic murine models with targeted gene ablation have allowed us to identify a complex network of paracrine signaling between the endometrial epithelium and stroma. While some of the critical molecules have been identified, the mechanism underlying the intricate communication between endometrial compartments during the implantation window has not been fully elucidated. Defining this mechanism will help identify markers of a receptive uterine environment, ultimately providing a useful tool to help improve the fertility outlook for reproductively challenged couples. The aim of this review is to outline our current understanding of how nuclear receptors and their effector molecules regulate blastocyst implantation in the endometrium.

A decrease in serum estradiol levels after human chorionic gonadotrophin administration predicts significantly lower clinical pregnancy and live birth rates in in vitro fertilization cycles

BACKGROUND

Although close observation of serum estradiol (E2) levels remains a mainstay of assessing clinical response to controlled ovarian stimulation, the prognostic value of any change in E2 levels after administration of hCG remains unclear. The objective of this study is to evaluate the relationship between serum E2 response after hCG administration and the clinical pregnancy and live birth rates in fresh IVF cycles.

METHODS

We conducted a retrospective cohort study of women aged 21-45 years undergoing their first IVF cycle from 1999 to 2008 at a single practice. We compared the post-hCG serum E2 level with values on the day of hCG trigger. IVF cycles were stratified by post-hCG E2 response and appropriate parametric and non-parametric statistics were performed. Clinical intrauterine pregnancy and live births were the primary outcomes of interest. Multivariable logistic regression models were created to identify predictive factors associated with outcomes while adjusting for potential confounders.

RESULTS

Among the 1712 IVF cycles, 1065 exhibited a >10% increase (Group A), 525 had a plateau (± 10%, Group B) and 122 showed a >10% decrease (Group C) in post-hCG E2 levels. While the E2 levels on the day of hCG were similar across groups, Group C had more patients with diminished ovarian reserve, required higher gonadotrophin doses and had the lowest implantation rates. After adjusting for age, total gonadotrophin dose, infertility diagnosis, number of oocytes and number of transferred embryos, the associations between post-hCG E2 decline (Group C) and clinical pregnancy [adjusted odds ratio (aOR): 0.53; 95% confidence interval (CI): 0.33-0.84, P= 0.007] and live birth (aOR: 0.40; 95% CI: 0.22-0.71, P= 0.002) were significant. We also found significant associations between E2 plateau (Group B) and clinical pregnancy (aOR: 0.73; 95% CI: 0.57-0.94, P= 0.013) and live birth (aOR: 0.74; 95% CI: 0.56-0.97, P= 0.032) when adjusting for the same factors.

CONCLUSIONS

In our study, >10% decrease in E2 levels after hCG administration was associated with 40-50% reduction in clinical pregnancy and live birth rates. Similarly, post-hCG E2 plateau (± 10%) lowered the clinical pregnancy and live birth rates by >25%. Our study suggests that the change in the post-hCG E2 level is another parameter that can be used by clinicians to counsel patients regarding their likelihood of success with assisted reproductive technologies prior to oocyte retrieval.

LIF and sIL-2R plasma concentrations in IVF patients on the day of embryo transfer: predictive markers of IVF outcome

Successful implantation is still the limiting step in IVF. We hypothesized that maternal plasma concentrations of certain cytokines at the time of embryo transfer could predict the likelihood of successful implantation and pregnancy. sIL-2R, IL-6, LIF, and MMP2 concentrations were measured in plasma from 160 IVF patients (natural and stimulated IVF cycles) on the morning of the embryo transfer (ET0) and 14 days later (ET+14). Patients were ultimately subdivided into four groups depending on the IVF treatment outcome (pregnancy failure, biochemical pregnancy, first-trimester miscarriage and normal term delivery). In natural and stimulated IVF cycles at ET0, sIL-2R concentrations were threefold higher in biochemical pregnancies than in pregnancy failures (P=0.020), and in natural cycles only, 2.5-fold higher in normal term deliveries than in pregnancy failures (P=0.023). Conversely, in natural and stimulated IVF cycles at ET0, LIF concentrations were one third lower in biochemical pregnancies/first-trimester miscarriages compared with pregnancy failures (P=0.042). We suggest that high sIL-2R and low LIF concentrations in maternal plasma on the morning of the embryo transfer might be associated with increased risks of early pregnancy loss, while a basal level of sIL-2R is necessary for normal term delivery outcome. Both cytokine measurements might therefore be useful in the management of IVF patients, and modulation of their concentrations could be investigated as a therapeutic alternative for women with abnormal concentrations at the time of embryo transfer.

Can serum oestradiol be a predictor of quality of oocytes and embryos, maturation of oocytes and pregnancy rate in ICSI cycles?

Our aim was to assess the influence of ratios of oestradiol (E2) to either number of follicles ≥ 14 mm on the day of human chorionic gonadotropin administration (E2/fol) or the number of oocytes retrieved (E2/o) during oocyte pick up and total serum E2 levels on the day of embryo transfer (ETE2) on the outcome of ICSI cycles. The assessed outcomes were number of oocytes retrieved (NRO), number of mature oocytes (NMO), number of fertilised oocytes (NFO), number of transferred embryos (NTE), qualities of oocytes (OQS), qualities of embryos (EQS) and pregnancy rates (PR). Two hundred and twenty-seven ICSI-ET cycles admitted to our IVF clinic during a 2-year period with normal ovarian reserve receiving long luteal GnRH agonist protocol were included. The E2/fol levels correlated positively with NRO (r = 0.202, p = 0.002), NMO (r = 0.199, p = 0.003) and NFO (r = 0.159, p = 0.018). However, we observed negative correlations between E2/o and NMO (r = -0.329, p <0.001), NFO (r = -0.219, p = 0.001), EQ5 (r = -0.203, p = 0.040). Oocyte quality scores were not affected from either E2/fol or E2/o levels. Implantation, clinical and ongoing PRs were comparable between groups categorised due to E2/fol, E2/o and ETE2. It seems that high E2/fol ratio may have beneficial effects on NRO, NMO and NFO while E2/o may adversely affect these parameters. Neither of the E2 levels is associated with pregnancy rates in women with normal ovarian reserve.

Increased preconception omega-3 polyunsaturated fatty acid intake improves embryo morphology

The association between preconception dietary intake of the polyunsaturated fatty acids (LC-PUFAs) omega-6 and omega-3 and the E(2) levels and IVF/intracytoplasmic sperm injection (ICSI) outcome were investigated in women in a prospective study. It revealed that high intakes of omega-3 LC-PUFA alpha-linolenic acid increase baseline E(2), high intakes of eicosapentaenoic acid and docosahexaenoic acid reduce E(2) response and the number of follicles after ovarian stimulation, and total omega-3 intake, in particular alpha-linolenic acid and docosahexaenoic acid, improve embryo morphology.